diff --git a/Neos.Cache/Classes/Backend/AbstractBackend.php b/Neos.Cache/Classes/Backend/AbstractBackend.php
index 05dab6c87b..51f1582c88 100644
--- a/Neos.Cache/Classes/Backend/AbstractBackend.php
+++ b/Neos.Cache/Classes/Backend/AbstractBackend.php
@@ -28,18 +28,18 @@ abstract class AbstractBackend implements BackendInterface
 
     /**
      * Reference to the cache frontend which uses this backend
-     * @var FrontendInterface
+     * @var ?FrontendInterface
      */
     protected $cache;
 
     /**
-     * @var string
+     * @var ?string
      */
     protected $cacheIdentifier;
 
     /**
-     * A prefix to seperate stored by appliaction context and cache
-     * @var string
+     * A prefix to separate stored by application context and cache
+     * @var ?string
      */
     protected $identifierPrefix;
 
@@ -50,28 +50,25 @@ abstract class AbstractBackend implements BackendInterface
     protected $defaultLifetime = 3600;
 
     /**
-     * @var EnvironmentConfiguration
+     * @var ?EnvironmentConfiguration
      */
     protected $environmentConfiguration;
 
     /**
      * Constructs this backend
      *
-     * @param EnvironmentConfiguration $environmentConfiguration
-     * @param array $options Configuration options - depends on the actual backend
+     * @param ?EnvironmentConfiguration $environmentConfiguration @todo is this ever null and does that even make sense?
+     * @param array<mixed> $options Configuration options - depends on the actual backend
      * @api
      */
     public function __construct(?EnvironmentConfiguration $environmentConfiguration = null, array $options = [])
     {
         $this->environmentConfiguration = $environmentConfiguration;
-
-        if (is_array($options) || $options instanceof \Iterator) {
-            $this->setProperties($options);
-        }
+        $this->setProperties($options);
     }
 
     /**
-     * @param array $properties
+     * @param array<mixed> $properties
      * @param boolean $throwExceptionIfPropertyNotSettable
      * @return void
      * @throws \InvalidArgumentException
diff --git a/Neos.Cache/Classes/Backend/ApcuBackend.php b/Neos.Cache/Classes/Backend/ApcuBackend.php
index 6d48971bef..718ff6b500 100644
--- a/Neos.Cache/Classes/Backend/ApcuBackend.php
+++ b/Neos.Cache/Classes/Backend/ApcuBackend.php
@@ -83,6 +83,10 @@ public function setCache(FrontendInterface $cache): void
     {
         parent::setCache($cache);
 
+        if ($this->environmentConfiguration === null) {
+            throw new \RuntimeException('The environment configuration is not set.', 1744537489);
+        }
+
         $pathHash = substr(md5($this->environmentConfiguration->getApplicationIdentifier() . $cache->getIdentifier()), 0, 12);
         $this->identifierPrefix = 'Flow_' . $pathHash . '_';
     }
@@ -110,7 +114,7 @@ public function getPrefixedIdentifier(string $entryIdentifier): string
      *
      * @param string $entryIdentifier An identifier for this specific cache entry
      * @param string $data The data to be stored
-     * @param array $tags Tags to associate with this cache entry
+     * @param array<string> $tags Tags to associate with this cache entry
      * @param int|null $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @return void
      * @throws Exception if no cache frontend has been set.
@@ -263,7 +267,7 @@ public function flushByTags(array $tags): int
      * Associates the identifier with the given tags
      *
      * @param string $entryIdentifier
-     * @param array $tags
+     * @param array<string> $tags
      * @return void
      */
     protected function addIdentifierToTags(string $entryIdentifier, array $tags)
@@ -391,6 +395,7 @@ public function valid(): bool
      *
      * @return void
      * @api
+     * @phpstan-assert \APCUIterator $this->cacheEntriesIterator
      */
     #[\ReturnTypeWillChange]
     public function rewind()
diff --git a/Neos.Cache/Classes/Backend/BackendInterface.php b/Neos.Cache/Classes/Backend/BackendInterface.php
index fbb29e4228..734a0ccace 100644
--- a/Neos.Cache/Classes/Backend/BackendInterface.php
+++ b/Neos.Cache/Classes/Backend/BackendInterface.php
@@ -50,7 +50,7 @@ public function getPrefixedIdentifier(string $entryIdentifier): string;
      *
      * @param string $entryIdentifier An identifier for this specific cache entry
      * @param string $data The data to be stored
-     * @param array $tags Tags to associate with this cache entry. If the backend does not support tags, this option can be ignored.
+     * @param array<string> $tags Tags to associate with this cache entry. If the backend does not support tags, this option can be ignored.
      * @param integer|null $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @return void
      * @throws \Neos\Cache\Exception if no cache frontend has been set.
diff --git a/Neos.Cache/Classes/Backend/FileBackend.php b/Neos.Cache/Classes/Backend/FileBackend.php
index 18a99b72aa..bbf9194408 100644
--- a/Neos.Cache/Classes/Backend/FileBackend.php
+++ b/Neos.Cache/Classes/Backend/FileBackend.php
@@ -48,7 +48,7 @@ class FileBackend extends SimpleFileBackend implements PhpCapableBackendInterfac
     protected $cacheEntryFileExtension = '';
 
     /**
-     * @var array<string>
+     * @var array<string, true> @phpstan-ignore property.phpDocType (this backend seems to work differently)
      */
     protected $cacheEntryIdentifiers = [];
 
@@ -90,6 +90,9 @@ public function freeze(): void
         $cachePathAndFileName = $this->cacheDirectory . 'FrozenCache.data';
         if ($this->useIgBinary === true) {
             $data = igbinary_serialize($this->cacheEntryIdentifiers);
+            if ($data === null) {
+                throw new \RuntimeException('Failed to serialize cache entry identifiers', 1744536663);
+            }
         } else {
             $data = serialize($this->cacheEntryIdentifiers);
         }
@@ -140,8 +143,8 @@ public function setCache(FrontendInterface $cache): void
      *
      * @param string $entryIdentifier An identifier for this specific cache entry
      * @param string $data The data to be stored
-     * @param array $tags Tags to associate with this cache entry
-     * @param integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
+     * @param array<string> $tags Tags to associate with this cache entry
+     * @param ?integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @return void
      * @throws \RuntimeException
      * @throws Exception if the directory does not exist or is not writable or exceeds the maximum allowed path length, or if no cache frontend has been set.
diff --git a/Neos.Cache/Classes/Backend/IterableBackendInterface.php b/Neos.Cache/Classes/Backend/IterableBackendInterface.php
index 7815216fba..238efc397d 100644
--- a/Neos.Cache/Classes/Backend/IterableBackendInterface.php
+++ b/Neos.Cache/Classes/Backend/IterableBackendInterface.php
@@ -14,6 +14,7 @@
 /**
  * A contract for a cache backend which provides Iterator functionality.
  *
+ * @extends \Iterator<int|string,mixed>
  * @api
  */
 interface IterableBackendInterface extends BackendInterface, \Iterator
diff --git a/Neos.Cache/Classes/Backend/IterableMultiBackend.php b/Neos.Cache/Classes/Backend/IterableMultiBackend.php
index 40ab0e408e..2e13e2356c 100644
--- a/Neos.Cache/Classes/Backend/IterableMultiBackend.php
+++ b/Neos.Cache/Classes/Backend/IterableMultiBackend.php
@@ -45,6 +45,9 @@ public function current(): mixed
         $this->prepareBackends();
         foreach ($this->backends as $backend) {
             try {
+                if (!method_exists($backend, 'current')) {
+                    throw new \RuntimeException(get_class($backend) . ' does not implement rewind');
+                }
                 return $backend->current();
             } catch (Throwable $throwable) {
                 $this->logger?->error('Failed retrieving current cache entry using backend ' . get_class($backend) . ' in ' . get_class($this) . ': ' . $this->throwableStorage?->logThrowable($throwable), LogEnvironment::fromMethodName(__METHOD__));
@@ -63,6 +66,9 @@ public function next(): void
         $this->prepareBackends();
         foreach ($this->backends as $backend) {
             try {
+                if (!method_exists($backend, 'next')) {
+                    throw new \RuntimeException(get_class($backend) . ' does not implement rewind');
+                }
                 $backend->next();
             } catch (Throwable $throwable) {
                 $this->logger?->error('Failed retrieving next cache entry using backend ' . get_class($backend) . ' in ' . get_class($this) . ': ' . $this->throwableStorage?->logThrowable($throwable), LogEnvironment::fromMethodName(__METHOD__));
@@ -80,6 +86,9 @@ public function key(): string|int|bool|null|float
         $this->prepareBackends();
         foreach ($this->backends as $backend) {
             try {
+                if (!method_exists($backend, 'key')) {
+                    throw new \RuntimeException(get_class($backend) . ' does not implement rewind');
+                }
                 return $backend->key();
             } catch (Throwable $throwable) {
                 $this->logger?->error('Failed retrieving cache entry key using backend ' . get_class($backend) . ' in ' . get_class($this) . ': ' . $this->throwableStorage?->logThrowable($throwable), LogEnvironment::fromMethodName(__METHOD__));
@@ -98,6 +107,9 @@ public function valid(): bool
         $this->prepareBackends();
         foreach ($this->backends as $backend) {
             try {
+                if (!method_exists($backend, 'valid')) {
+                    throw new \RuntimeException(get_class($backend) . ' does not implement rewind');
+                }
                 return $backend->valid();
             } catch (Throwable $throwable) {
                 $this->logger?->error('Failed checking if current cache entry is valid using backend ' . get_class($backend) . ' in ' . get_class($this) . ': ' . $this->throwableStorage?->logThrowable($throwable), LogEnvironment::fromMethodName(__METHOD__));
@@ -116,6 +128,9 @@ public function rewind(): void
         $this->prepareBackends();
         foreach ($this->backends as $backend) {
             try {
+                if (!method_exists($backend, 'rewind')) {
+                    throw new \RuntimeException(get_class($backend) . ' does not implement rewind');
+                }
                 $backend->rewind();
             } catch (Throwable $throwable) {
                 $this->logger?->error('Failed rewinding cache entries using backend ' . get_class($backend) . ' in ' . get_class($this) . ': ' . $this->throwableStorage?->logThrowable($throwable), LogEnvironment::fromMethodName(__METHOD__));
diff --git a/Neos.Cache/Classes/Backend/MemcachedBackend.php b/Neos.Cache/Classes/Backend/MemcachedBackend.php
index af6adecaa9..08ab205a19 100644
--- a/Neos.Cache/Classes/Backend/MemcachedBackend.php
+++ b/Neos.Cache/Classes/Backend/MemcachedBackend.php
@@ -65,7 +65,7 @@ class MemcachedBackend extends IndependentAbstractBackend implements TaggableBac
     /**
      * Array of Memcache server configurations
      *
-     * @var array
+     * @var array<string>
      */
     protected $servers = [];
 
@@ -102,7 +102,7 @@ public function __construct(EnvironmentConfiguration $environmentConfiguration,
      * Setter for servers to be used. Expects an array,  the values are expected
      * to be formatted like "<host>[:<port>]" or "unix://<path>"
      *
-     * @param array $servers An array of servers to add.
+     * @param array<string> $servers An array of servers to add.
      * @return void
      * @throws Exception
      * @api
@@ -121,12 +121,12 @@ protected function setServers(array $servers)
             $host = $server;
             $port = 0;
 
-            if (strpos($server, 'tcp://') === 0) {
+            if (str_starts_with($server, 'tcp://')) {
                 $port = $defaultPort;
                 $server = substr($server, 6);
             }
 
-            if (strpos($server, ':') !== false) {
+            if (str_contains($server, ':')) {
                 [$host, $portValue] = explode(':', $server, 2);
                 $port = (int)$portValue;
             }
@@ -165,6 +165,10 @@ public function setCache(FrontendInterface $cache): void
     {
         parent::setCache($cache);
 
+        if ($this->environmentConfiguration === null) {
+            throw new \RuntimeException('No environment configuration set', 1744535714);
+        }
+
         $pathHash = substr(md5($this->environmentConfiguration->getApplicationIdentifier() . $cache->getIdentifier()), 0, 12);
         $this->identifierPrefix = 'Flow_' . $pathHash . '_';
     }
@@ -192,8 +196,8 @@ public function getPrefixedIdentifier(string $entryIdentifier): string
      *
      * @param string $entryIdentifier An identifier for this specific cache entry
      * @param string $data The data to be stored
-     * @param array $tags Tags to associate with this cache entry
-     * @param integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
+     * @param array<string> $tags Tags to associate with this cache entry
+     * @param ?integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @return void
      * @throws Exception if no cache frontend has been set.
      * @throws \InvalidArgumentException if the identifier is not valid or the final memcached key is longer than 250 characters
@@ -325,7 +329,7 @@ public function findIdentifiersByTag(string $tag): array
      * index to search for tags.
      *
      * @param string $identifier Identifier to find tags by
-     * @return array Array with tags
+     * @return array<string> Array with tags
      */
     protected function findTagsByIdentifier(string $identifier): array
     {
@@ -383,7 +387,7 @@ public function flushByTags(array $tags): int
      * Associates the identifier with the given tags
      *
      * @param string $entryIdentifier
-     * @param array $tags
+     * @param array<string> $tags
      * @return void
      */
     protected function addIdentifierToTags(string $entryIdentifier, array $tags)
diff --git a/Neos.Cache/Classes/Backend/MultiBackend.php b/Neos.Cache/Classes/Backend/MultiBackend.php
index 4fc3715079..1d5293dd88 100644
--- a/Neos.Cache/Classes/Backend/MultiBackend.php
+++ b/Neos.Cache/Classes/Backend/MultiBackend.php
@@ -30,7 +30,13 @@ class MultiBackend extends AbstractBackend
 {
     use BackendInstantiationTrait;
 
+    /**
+     * @var array<mixed>
+     */
     protected array $backendConfigurations = [];
+    /**
+     * @var array<int,BackendInterface>
+     */
     protected array $backends = [];
     protected bool $setInAllBackends = true;
     protected bool $debug = false;
@@ -48,10 +54,8 @@ public function __construct(?EnvironmentConfiguration $environmentConfiguration
         if ($this->logErrors && class_exists(Bootstrap::class) && Bootstrap::$staticObjectManager instanceof ObjectManagerInterface) {
             try {
                 $logger = Bootstrap::$staticObjectManager->get(LoggerInterface::class);
-                assert($logger instanceof LoggerInterface);
                 $this->logger = $logger;
                 $throwableStorage = Bootstrap::$staticObjectManager->get(ThrowableStorageInterface::class);
-                assert($throwableStorage instanceof ThrowableStorageInterface);
                 $this->throwableStorage = $throwableStorage;
             } catch (UnknownObjectException) {
                 // Logging might not be available during compile time
@@ -78,11 +82,18 @@ protected function prepareBackends(): void
     }
 
     /**
+     * @param array<mixed> $backendOptions
      * @throws Throwable
      */
     protected function buildSubBackend(string $backendClassName, array $backendOptions): ?BackendInterface
     {
         try {
+            if ($this->cache === null) {
+                throw new \RuntimeException('Cache frontend is not yet initialized', 1744535490);
+            }
+            if ($this->environmentConfiguration === null) {
+                throw new \RuntimeException('Environment configuration is missing', 1744535532);
+            }
             $backend = $this->instantiateBackend($backendClassName, $backendOptions, $this->environmentConfiguration);
             $backend->setCache($this->cache);
         } catch (Throwable $throwable) {
@@ -95,6 +106,7 @@ protected function buildSubBackend(string $backendClassName, array $backendOptio
 
     /**
      * @throws Throwable
+     * @param array<string> $tags
      */
     public function set(string $entryIdentifier, string $data, array $tags = [], ?int $lifetime = null): void
     {
@@ -204,6 +216,7 @@ public function collectGarbage(): void
 
     /**
      * This setter is used by AbstractBackend::setProperties()
+     * @param array<mixed> $backendConfigurations
      */
     protected function setBackendConfigurations(array $backendConfigurations): void
     {
diff --git a/Neos.Cache/Classes/Backend/NullBackend.php b/Neos.Cache/Classes/Backend/NullBackend.php
index e01c90292e..2148fad548 100644
--- a/Neos.Cache/Classes/Backend/NullBackend.php
+++ b/Neos.Cache/Classes/Backend/NullBackend.php
@@ -41,8 +41,8 @@ protected function setProperty(string $propertyName, $propertyValue) : bool
      *
      * @param string $entryIdentifier ignored
      * @param string $data ignored
-     * @param array $tags ignored
-     * @param integer $lifetime ignored
+     * @param array<string> $tags ignored
+     * @param ?integer $lifetime ignored
      * @return void
      * @api
      */
diff --git a/Neos.Cache/Classes/Backend/PdoBackend.php b/Neos.Cache/Classes/Backend/PdoBackend.php
index 5c772a6dc5..12cda08799 100644
--- a/Neos.Cache/Classes/Backend/PdoBackend.php
+++ b/Neos.Cache/Classes/Backend/PdoBackend.php
@@ -48,7 +48,7 @@ class PdoBackend extends IndependentAbstractBackend implements TaggableBackendIn
     protected $password;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $driverOptions = [];
 
@@ -83,7 +83,7 @@ class PdoBackend extends IndependentAbstractBackend implements TaggableBackendIn
     protected $batchSize = 999;
 
     /**
-     * @var \ArrayIterator|null
+     * @var \ArrayIterator<string,mixed>|null
      */
     protected $cacheEntriesIterator;
 
@@ -126,7 +126,7 @@ protected function setPassword(string $password): void
     /**
      * Sets the driverOptions to use
      *
-     * @param array $driverOptions The options to use for connecting to the DB
+     * @param array<mixed> $driverOptions The options to use for connecting to the DB
      * @return void
      * @api
      */
@@ -174,7 +174,7 @@ protected function setBatchSize(int $batchSize): void
      *
      * @param string $entryIdentifier An identifier for this specific cache entry
      * @param string $data The data to be stored
-     * @param array $tags Tags to associate with this cache entry
+     * @param array<string> $tags Tags to associate with this cache entry
      * @param int|null $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @return void
      * @throws Exception if no cache frontend has been set.
@@ -613,6 +613,7 @@ public function valid(): bool
      *
      * @return void
      * @api
+     * @phpstan-assert \ArrayIterator<string,mixed> $this->cacheEntriesIterator
      */
     public function rewind(): void
     {
@@ -647,6 +648,9 @@ public function rewind(): void
     protected function context(): string
     {
         if ($this->context === null) {
+            if ($this->environmentConfiguration === null) {
+                throw new \RuntimeException('Environment configuration not set', 1744534618);
+            }
             $this->context = md5($this->environmentConfiguration->getApplicationIdentifier());
         }
         return $this->context;
diff --git a/Neos.Cache/Classes/Backend/RedisBackend.php b/Neos.Cache/Classes/Backend/RedisBackend.php
index 329f96de5e..3aca115e6a 100644
--- a/Neos.Cache/Classes/Backend/RedisBackend.php
+++ b/Neos.Cache/Classes/Backend/RedisBackend.php
@@ -79,7 +79,7 @@ class RedisBackend extends IndependentAbstractBackend implements TaggableBackend
     protected int $batchSize = 100000;
 
     /**
-     * @var \ArrayIterator|null
+     * @var \ArrayIterator<int,string>|null
      */
     private $entryIterator;
 
@@ -87,15 +87,14 @@ class RedisBackend extends IndependentAbstractBackend implements TaggableBackend
      * Constructs this backend
      *
      * @param EnvironmentConfiguration $environmentConfiguration
-     * @param array $options Configuration options - depends on the actual backend
+     * @param array<mixed> $options Configuration options - depends on the actual backend
      * @throws CacheException
+     * @phpstan-assert EnvironmentConfiguration $this->environmentConfiguration
      */
     public function __construct(EnvironmentConfiguration $environmentConfiguration, array $options)
     {
         parent::__construct($environmentConfiguration, $options);
-        if (!$this->redis instanceof \Redis) {
-            $this->redis = $this->getRedisClient();
-        }
+        $this->redis = $this->getRedisClient();
     }
 
     /**
@@ -103,7 +102,7 @@ public function __construct(EnvironmentConfiguration $environmentConfiguration,
      *
      * @param string $entryIdentifier An identifier for this specific cache entry
      * @param string $data The data to be stored
-     * @param array $tags Tags to associate with this cache entry. If the backend does not support tags, this option can be ignored.
+     * @param array<string> $tags Tags to associate with this cache entry. If the backend does not support tags, this option can be ignored.
      * @param integer|null $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @throws \RuntimeException
      * @throws CacheException
@@ -425,7 +424,6 @@ public function freeze(): void
             foreach ($iterator as $entryIdentifier) {
                 $this->redis->persist($this->getPrefixedIdentifier('entry:' . $entryIdentifier));
             }
-            /** @var array|bool $result */
             $result = $this->redis->exec();
             $this->redis->set($this->getPrefixedIdentifier('frozen'), 1);
         } while ($result === false);
@@ -510,7 +508,13 @@ private function uncompress(bool|string $value): bool|string
 
     private function compress(string $value): string
     {
-        return $this->useCompression() ? gzencode($value, $this->compressionLevel) : $value;
+        if ($this->useCompression()) {
+            $value = gzencode($value, $this->compressionLevel);
+            if ($value === false) {
+                throw new \RuntimeException('Failed to compress value with gzencode', 1744534319);
+            }
+        }
+        return $value;
     }
 
     private function useCompression(): bool
diff --git a/Neos.Cache/Classes/Backend/RequireOnceFromValueTrait.php b/Neos.Cache/Classes/Backend/RequireOnceFromValueTrait.php
index 5cc7809103..94786d597f 100644
--- a/Neos.Cache/Classes/Backend/RequireOnceFromValueTrait.php
+++ b/Neos.Cache/Classes/Backend/RequireOnceFromValueTrait.php
@@ -19,7 +19,7 @@
 trait RequireOnceFromValueTrait
 {
     /**
-     * @var array
+     * @var array<string,true>
      */
     protected $_requiredEntryIdentifiers = [];
 
diff --git a/Neos.Cache/Classes/Backend/SimpleFileBackend.php b/Neos.Cache/Classes/Backend/SimpleFileBackend.php
index 6f3e346b0b..598ea30de9 100644
--- a/Neos.Cache/Classes/Backend/SimpleFileBackend.php
+++ b/Neos.Cache/Classes/Backend/SimpleFileBackend.php
@@ -82,12 +82,13 @@ class SimpleFileBackend extends IndependentAbstractBackend implements PhpCapable
      * the effective directory will be a subdirectory of this.
      * If not given this will be determined by the EnvironmentConfiguration
      *
-     * @var string
+     * @var ?string
      */
     protected $baseDirectory;
 
     /**
      * {@inheritdoc}
+     * @param array<mixed> $options
      */
     public function __construct(EnvironmentConfiguration $environmentConfiguration, array $options = [])
     {
@@ -138,7 +139,7 @@ public function getCacheDirectory(): string
      *
      * @param string $entryIdentifier An identifier for this specific cache entry
      * @param string $data The data to be stored
-     * @param array $tags Ignored in this type of cache backend
+     * @param array<string> $tags Ignored in this type of cache backend
      * @param int|null $lifetime Ignored in this type of cache backend
      * @return void
      * @throws Exception if the directory does not exist or is not writable or exceeds the maximum allowed path length, or if no cache frontend has been set.
@@ -408,6 +409,7 @@ public function valid(): bool
      *
      * @return void
      * @api
+     * @phpstan-assert \DirectoryIterator $this->cacheFilesIterator
      */
     public function rewind(): void
     {
@@ -427,15 +429,15 @@ public function rewind(): void
      */
     protected function throwExceptionIfPathExceedsMaximumLength(string $cacheEntryPathAndFilename): void
     {
-        if (strlen($cacheEntryPathAndFilename) > $this->environmentConfiguration->getMaximumPathLength()) {
-            throw new Exception('The length of the cache entry path "' . $cacheEntryPathAndFilename . '" exceeds the maximum path length of ' . $this->environmentConfiguration->getMaximumPathLength() . '. Please consider setting the FLOW_PATH_TEMPORARY_BASE environment variable to a shorter path. ', 1248710426);
+        if (strlen($cacheEntryPathAndFilename) > $this->environmentConfiguration?->getMaximumPathLength()) {
+            throw new Exception('The length of the cache entry path "' . $cacheEntryPathAndFilename . '" exceeds the maximum path length of ' . $this->environmentConfiguration?->getMaximumPathLength() . '. Please consider setting the FLOW_PATH_TEMPORARY_BASE environment variable to a shorter path. ', 1248710426);
         }
     }
 
     /**
-     * @return string
+     * @return ?string
      */
-    public function getBaseDirectory(): string
+    public function getBaseDirectory(): ?string
     {
         return $this->baseDirectory;
     }
@@ -456,7 +458,10 @@ protected function configureCacheDirectory(): void
         $cacheDirectory = $this->cacheDirectory;
         if ($cacheDirectory === '') {
             $codeOrData = ($this->cache instanceof PhpFrontend) ? 'Code' : 'Data';
-            $baseDirectory = ($this->baseDirectory ?: $this->environmentConfiguration->getFileCacheBasePath());
+            $baseDirectory = ($this->baseDirectory ?: $this->environmentConfiguration?->getFileCacheBasePath());
+            if ($baseDirectory === null) {
+                throw new \RuntimeException('Could not resolve base directory for SimpleFileBackend', 1744534007);
+            }
             $cacheDirectory = $baseDirectory . 'Cache/' . $codeOrData . '/' . $this->cacheIdentifier . '/';
         }
 
@@ -504,9 +509,9 @@ protected function readCacheFile(string $cacheEntryPathAndFilename, int $offset
                 }
                 if (flock($file, LOCK_SH) !== false) {
                     $data = '';
-                    if ($maxlen !== 0) {
-                        $data = $maxlen !== null ? file_get_contents($cacheEntryPathAndFilename, false, null, $offset, $maxlen) : file_get_contents($cacheEntryPathAndFilename, false, null, $offset);
-                    }
+                    $data = $maxlen > 0
+                        ? file_get_contents($cacheEntryPathAndFilename, false, null, $offset, $maxlen)
+                        : file_get_contents($cacheEntryPathAndFilename, false, null, $offset);
 
                     flock($file, LOCK_UN);
                 }
diff --git a/Neos.Cache/Classes/Backend/TaggableMultiBackend.php b/Neos.Cache/Classes/Backend/TaggableMultiBackend.php
index aef92b8b3f..3ce1ac7aa1 100644
--- a/Neos.Cache/Classes/Backend/TaggableMultiBackend.php
+++ b/Neos.Cache/Classes/Backend/TaggableMultiBackend.php
@@ -23,6 +23,7 @@
 class TaggableMultiBackend extends MultiBackend implements TaggableBackendInterface
 {
     /**
+     * @param array<mixed> $backendOptions
      * @throws Throwable
      */
     protected function buildSubBackend(string $backendClassName, array $backendOptions): ?BackendInterface
@@ -46,6 +47,9 @@ public function flushByTag(string $tag): int
         $flushed = 0;
         foreach ($this->backends as $backend) {
             try {
+                if (!method_exists($backend, 'flushByTag')) {
+                    throw new \RuntimeException(get_class($backend) . ' does not implement flushByTag');
+                }
                 $flushed += $backend->flushByTag($tag);
             } catch (Throwable $throwable) {
                 $this->logger?->error('Failed flushing cache by tag using backend ' . get_class($backend) . ' in ' . get_class($this) . ': ' . $this->throwableStorage?->logThrowable($throwable), LogEnvironment::fromMethodName(__METHOD__));
@@ -80,6 +84,9 @@ public function findIdentifiersByTag(string $tag): array
         $identifiers = [];
         foreach ($this->backends as $backend) {
             try {
+                if (!method_exists($backend, 'findIdentifiersByTag')) {
+                    throw new \RuntimeException(get_class($backend) . ' does not implement findIdentifiersByTag');
+                }
                 $identifiers[] = $backend->findIdentifiersByTag($tag);
             } catch (Throwable $throwable) {
                 $this->logger?->error('Failed finding identifiers by tag using backend ' . get_class($backend) . ' in ' . get_class($this) . ': ' . $this->throwableStorage?->logThrowable($throwable), LogEnvironment::fromMethodName(__METHOD__));
diff --git a/Neos.Cache/Classes/Backend/TransientMemoryBackend.php b/Neos.Cache/Classes/Backend/TransientMemoryBackend.php
index 1ea561187c..c57036cbdf 100644
--- a/Neos.Cache/Classes/Backend/TransientMemoryBackend.php
+++ b/Neos.Cache/Classes/Backend/TransientMemoryBackend.php
@@ -25,12 +25,12 @@
 class TransientMemoryBackend extends IndependentAbstractBackend implements TaggableBackendInterface
 {
     /**
-     * @var array
+     * @var array<string,string>
      */
     protected $entries = [];
 
     /**
-     * @var array
+     * @var array<string,array<string,true>>
      */
     protected $tagsAndEntries = [];
 
@@ -39,8 +39,8 @@ class TransientMemoryBackend extends IndependentAbstractBackend implements Tagga
      *
      * @param string $entryIdentifier An identifier for this specific cache entry
      * @param string $data The data to be stored
-     * @param array $tags Tags to associate with this cache entry
-     * @param integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
+     * @param array<string> $tags Tags to associate with this cache entry
+     * @param ?integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @return void
      * @throws Exception if no cache frontend has been set.
      * @api
@@ -51,7 +51,6 @@ public function set(string $entryIdentifier, string $data, array $tags = [], ?in
             throw new Exception('No cache frontend has been set yet via setCache().', 1238244992);
         }
 
-
         $this->entries[$entryIdentifier] = $data;
         foreach ($tags as $tag) {
             $this->tagsAndEntries[$tag][$entryIdentifier] = true;
diff --git a/Neos.Cache/Classes/BackendInstantiationTrait.php b/Neos.Cache/Classes/BackendInstantiationTrait.php
index eb0c935968..42464cad84 100644
--- a/Neos.Cache/Classes/BackendInstantiationTrait.php
+++ b/Neos.Cache/Classes/BackendInstantiationTrait.php
@@ -21,7 +21,7 @@ trait BackendInstantiationTrait
 {
     /**
      * @param string $backendObjectName
-     * @param array $backendOptions
+     * @param array<mixed> $backendOptions
      * @param EnvironmentConfiguration $environmentConfiguration
      * @return BackendInterface
      * @throws InvalidBackendException
diff --git a/Neos.Cache/Classes/CacheFactory.php b/Neos.Cache/Classes/CacheFactory.php
index 7ce4e225db..c37dde8006 100644
--- a/Neos.Cache/Classes/CacheFactory.php
+++ b/Neos.Cache/Classes/CacheFactory.php
@@ -49,7 +49,7 @@ public function __construct(EnvironmentConfiguration $environmentConfiguration)
      * @param string $cacheIdentifier The name / identifier of the cache to create
      * @param string $cacheObjectName Object name of the cache frontend
      * @param string $backendObjectName Object name of the cache backend
-     * @param array $backendOptions (optional) Array of backend options
+     * @param array<mixed> $backendOptions (optional) Array of backend options
      * @return FrontendInterface The created cache frontend
      * @throws InvalidBackendException
      * @throws InvalidCacheException
diff --git a/Neos.Cache/Classes/CacheFactoryInterface.php b/Neos.Cache/Classes/CacheFactoryInterface.php
index 3bc72b7fef..1b85e27d74 100644
--- a/Neos.Cache/Classes/CacheFactoryInterface.php
+++ b/Neos.Cache/Classes/CacheFactoryInterface.php
@@ -30,7 +30,7 @@ interface CacheFactoryInterface
      * @param string $cacheIdentifier The name / identifier of the cache to create
      * @param string $cacheObjectName Object name of the cache frontend
      * @param string $backendObjectName Object name of the cache backend
-     * @param array $backendOptions (optional) Array of backend options
+     * @param array<mixed> $backendOptions (optional) Array of backend options
      * @return \Neos\Cache\Frontend\FrontendInterface The created cache frontend
      * @throws InvalidBackendException
      * @throws InvalidCacheException
diff --git a/Neos.Cache/Classes/Frontend/CacheEntryIterator.php b/Neos.Cache/Classes/Frontend/CacheEntryIterator.php
index 45ae20e2c1..b3244a4641 100644
--- a/Neos.Cache/Classes/Frontend/CacheEntryIterator.php
+++ b/Neos.Cache/Classes/Frontend/CacheEntryIterator.php
@@ -18,6 +18,7 @@
 /**
  * An iterator for cache entries
  *
+ * @implements \Iterator<string,mixed>
  * @api
  */
 class CacheEntryIterator implements \Iterator
diff --git a/Neos.Cache/Classes/Frontend/FrontendInterface.php b/Neos.Cache/Classes/Frontend/FrontendInterface.php
index 18fdf62b6f..b6e7a61c02 100644
--- a/Neos.Cache/Classes/Frontend/FrontendInterface.php
+++ b/Neos.Cache/Classes/Frontend/FrontendInterface.php
@@ -51,8 +51,8 @@ public function getBackend();
      *
      * @param string $entryIdentifier Something which identifies the data - depends on concrete cache
      * @param mixed $data The data to cache - also depends on the concrete cache implementation
-     * @param array $tags Tags to associate with this cache entry
-     * @param integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
+     * @param array<string> $tags Tags to associate with this cache entry
+     * @param ?integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @return void
      * @api
      */
@@ -71,7 +71,7 @@ public function get(string $entryIdentifier);
      * Finds and returns all cache entries which are tagged by the specified tag.
      *
      * @param string $tag The tag to search for
-     * @return array An array with the identifier (key) and content (value) of all matching entries. An empty array if no entries matched
+     * @return array<string,mixed> An array with the identifier (key) and content (value) of all matching entries. An empty array if no entries matched
      * @api
      */
     public function getByTag(string $tag): array;
diff --git a/Neos.Cache/Classes/Frontend/PhpFrontend.php b/Neos.Cache/Classes/Frontend/PhpFrontend.php
index c47efbab1f..11d442d3be 100644
--- a/Neos.Cache/Classes/Frontend/PhpFrontend.php
+++ b/Neos.Cache/Classes/Frontend/PhpFrontend.php
@@ -60,7 +60,7 @@ public function get(string $entryIdentifier)
 
         preg_match('/^(?:.*\n){1}((?:.*\n)*)(?:.+\n?|\n)$/', $code, $matches);
 
-        return $matches[1];
+        return $matches[1] ?? false;
     }
 
     /**
@@ -83,21 +83,22 @@ public function getWrapped(string $entryIdentifier)
      * Saves the PHP source code in the cache.
      *
      * @param string $entryIdentifier An identifier used for this cache entry, for example the class name
-     * @param string $sourceCode PHP source code
-     * @param array $tags Tags to associate with this cache entry
-     * @param integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
+     * @param string $data PHP source code
+     * @param array<string> $tags Tags to associate with this cache entry
+     * @param ?integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @return void
      * @throws InvalidDataException
      * @throws \InvalidArgumentException
      * @throws \Neos\Cache\Exception
      * @api
      */
-    public function set(string $entryIdentifier, $sourceCode, array $tags = [], ?int $lifetime = null)
+    public function set(string $entryIdentifier, $data, array $tags = [], ?int $lifetime = null)
     {
         if (!$this->isValidEntryIdentifier($entryIdentifier)) {
             throw new \InvalidArgumentException('"' . $entryIdentifier . '" is not a valid cache entry identifier.', 1264023823);
         }
-        if (!is_string($sourceCode)) {
+        /** @phpstan-ignore function.alreadyNarrowedType (we cannot narrow this on language level) */
+        if (!is_string($data)) {
             throw new InvalidDataException('The given source code is not a valid string.', 1264023824);
         }
         foreach ($tags as $tag) {
@@ -105,7 +106,7 @@ public function set(string $entryIdentifier, $sourceCode, array $tags = [], ?int
                 throw new \InvalidArgumentException('"' . $tag . '" is not a valid tag for a cache entry.', 1264023825);
             }
         }
-        $sourceCode = '<?php ' . $sourceCode . chr(10) . '#';
+        $sourceCode = '<?php ' . $data . chr(10) . '#';
         $this->backend->set($entryIdentifier, $sourceCode, $tags, $lifetime);
     }
 
diff --git a/Neos.Cache/Classes/Frontend/StringFrontend.php b/Neos.Cache/Classes/Frontend/StringFrontend.php
index e234b57ef7..829e83dba1 100644
--- a/Neos.Cache/Classes/Frontend/StringFrontend.php
+++ b/Neos.Cache/Classes/Frontend/StringFrontend.php
@@ -28,22 +28,23 @@ class StringFrontend extends AbstractFrontend
      * Saves the value of a PHP variable in the cache.
      *
      * @param string $entryIdentifier An identifier used for this cache entry
-     * @param string $string The variable to cache
-     * @param array $tags Tags to associate with this cache entry
-     * @param integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
+     * @param string $data The variable to cache
+     * @param array<string> $tags Tags to associate with this cache entry
+     * @param ?integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @return void
      * @throws InvalidDataException
      * @throws \InvalidArgumentException
      * @throws \Neos\Cache\Exception
      * @api
      */
-    public function set(string $entryIdentifier, $string, array $tags = [], ?int $lifetime = null)
+    public function set(string $entryIdentifier, $data, array $tags = [], ?int $lifetime = null)
     {
         if (!$this->isValidEntryIdentifier($entryIdentifier)) {
             throw new \InvalidArgumentException('"' . $entryIdentifier . '" is not a valid cache entry identifier.', 1233057566);
         }
-        if (!is_string($string)) {
-            throw new InvalidDataException('Given data is of type "' . gettype($string) . '", but a string is expected for string cache.', 1222808333);
+        /** @phpstan-ignore function.alreadyNarrowedType (we cannot narrow this on language level) */
+        if (!is_string($data)) {
+            throw new InvalidDataException('Given data is of type "' . gettype($data) . '", but a string is expected for string cache.', 1222808333);
         }
         foreach ($tags as $tag) {
             if (!$this->isValidTag($tag)) {
@@ -51,7 +52,7 @@ public function set(string $entryIdentifier, $string, array $tags = [], ?int $li
             }
         }
 
-        $this->backend->set($entryIdentifier, $string, $tags, $lifetime);
+        $this->backend->set($entryIdentifier, $data, $tags, $lifetime);
     }
 
     /**
@@ -75,7 +76,7 @@ public function get(string $entryIdentifier)
      * Finds and returns all cache entries which are tagged by the specified tag.
      *
      * @param string $tag The tag to search for
-     * @return array An array with the identifier (key) and content (value) of all matching entries. An empty array if no entries matched
+     * @return array<string,mixed> An array with the identifier (key) and content (value) of all matching entries. An empty array if no entries matched
      * @throws NotSupportedByBackendException
      * @throws \InvalidArgumentException
      * @api
diff --git a/Neos.Cache/Classes/Frontend/VariableFrontend.php b/Neos.Cache/Classes/Frontend/VariableFrontend.php
index 01602138dc..bc6d379f70 100644
--- a/Neos.Cache/Classes/Frontend/VariableFrontend.php
+++ b/Neos.Cache/Classes/Frontend/VariableFrontend.php
@@ -48,15 +48,15 @@ public function initializeObject()
      * will be serialized if necessary.
      *
      * @param string $entryIdentifier An identifier used for this cache entry
-     * @param mixed $variable The variable to cache
-     * @param array $tags Tags to associate with this cache entry
-     * @param integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
+     * @param mixed $data The variable to cache
+     * @param array<string> $tags Tags to associate with this cache entry
+     * @param ?integer $lifetime Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
      * @return void
      * @throws \InvalidArgumentException
      * @throws \Neos\Cache\Exception
      * @api
      */
-    public function set(string $entryIdentifier, $variable, array $tags = [], ?int $lifetime = null)
+    public function set(string $entryIdentifier, $data, array $tags = [], ?int $lifetime = null)
     {
         if (!$this->isValidEntryIdentifier($entryIdentifier)) {
             throw new \InvalidArgumentException('"' . $entryIdentifier . '" is not a valid cache entry identifier.', 1233058264);
@@ -67,9 +67,9 @@ public function set(string $entryIdentifier, $variable, array $tags = [], ?int $
             }
         }
         if ($this->useIgBinary === true) {
-            $this->backend->set($entryIdentifier, igbinary_serialize($variable), $tags, $lifetime);
+            $this->backend->set($entryIdentifier, igbinary_serialize($data) ?: '', $tags, $lifetime);
         } else {
-            $this->backend->set($entryIdentifier, serialize($variable), $tags, $lifetime);
+            $this->backend->set($entryIdentifier, serialize($data), $tags, $lifetime);
         }
     }
 
@@ -98,7 +98,7 @@ public function get(string $entryIdentifier)
      * Finds and returns all cache entries which are tagged by the specified tag.
      *
      * @param string $tag The tag to search for
-     * @return array An array with the identifier (key) and content (value) of all matching entries. An empty array if no entries matched
+     * @return array<string,mixed> An array with the identifier (key) and content (value) of all matching entries. An empty array if no entries matched
      * @throws NotSupportedByBackendException
      * @throws \InvalidArgumentException
      * @api
diff --git a/Neos.Cache/Classes/Psr/Cache/CacheFactory.php b/Neos.Cache/Classes/Psr/Cache/CacheFactory.php
index 9b2d73d6e9..0daeae17b1 100644
--- a/Neos.Cache/Classes/Psr/Cache/CacheFactory.php
+++ b/Neos.Cache/Classes/Psr/Cache/CacheFactory.php
@@ -48,7 +48,7 @@ public function __construct(EnvironmentConfiguration $environmentConfiguration)
      *
      * @param string $cacheIdentifier The name / identifier of the cache to create.
      * @param string $backendObjectName Object name of the cache backend
-     * @param array $backendOptions (optional) Array of backend options
+     * @param array<mixed> $backendOptions (optional) Array of backend options
      * @return CacheItemPoolInterface
      * @throws InvalidBackendException
      */
diff --git a/Neos.Cache/Classes/Psr/Cache/CachePool.php b/Neos.Cache/Classes/Psr/Cache/CachePool.php
index 998b0f4653..de83c88ebb 100644
--- a/Neos.Cache/Classes/Psr/Cache/CachePool.php
+++ b/Neos.Cache/Classes/Psr/Cache/CachePool.php
@@ -44,7 +44,7 @@ class CachePool implements CacheItemPoolInterface
     /**
      * A list of items still to be persisted.
      *
-     * @var array
+     * @var array<int,CacheItemInterface>
      */
     protected $deferredItems = [];
 
@@ -90,7 +90,7 @@ public function getItem(string $key): CacheItemInterface
      * Returns a traversable set of cache items.
      *
      * @param string[] $keys
-     * @return array
+     * @return array<CacheItemInterface>
      * @throws InvalidArgumentException
      */
     public function getItems(array $keys = []): iterable
diff --git a/Neos.Cache/Classes/Psr/SimpleCache/SimpleCache.php b/Neos.Cache/Classes/Psr/SimpleCache/SimpleCache.php
index 61ee172b06..38116ad4b4 100644
--- a/Neos.Cache/Classes/Psr/SimpleCache/SimpleCache.php
+++ b/Neos.Cache/Classes/Psr/SimpleCache/SimpleCache.php
@@ -133,7 +133,7 @@ public function clear(): bool
     }
 
     /**
-     * @param iterable $keys
+     * @param iterable<string> $keys
      * @param mixed $default
      * @return iterable<string, mixed>
      * @throws InvalidArgumentException
@@ -149,7 +149,7 @@ public function getMultiple(iterable $keys, mixed $default = null): iterable
     }
 
     /**
-     * @param iterable $values
+     * @param iterable<string> $values
      * @param null|int|\DateInterval $ttl
      * @return bool
      * @throws Exception
@@ -171,7 +171,7 @@ public function setMultiple(iterable $values, null|int|\DateInterval $ttl = null
     }
 
     /**
-     * @param iterable $keys
+     * @param iterable<string> $keys
      * @return bool
      * @throws InvalidArgumentException
      * @throws Exception
@@ -180,7 +180,7 @@ public function deleteMultiple(iterable $keys): bool
     {
         foreach ($keys as $key) {
             $this->delete($key);
-        };
+        }
 
         return true;
     }
diff --git a/Neos.Cache/Classes/Psr/SimpleCache/SimpleCacheFactory.php b/Neos.Cache/Classes/Psr/SimpleCache/SimpleCacheFactory.php
index 9daeb39c82..7c4e4ce6e7 100644
--- a/Neos.Cache/Classes/Psr/SimpleCache/SimpleCacheFactory.php
+++ b/Neos.Cache/Classes/Psr/SimpleCache/SimpleCacheFactory.php
@@ -48,7 +48,7 @@ public function __construct(EnvironmentConfiguration $environmentConfiguration)
      *
      * @param string $cacheIdentifier The name / identifier of the cache to create.
      * @param string $backendObjectName Object name of the cache backend
-     * @param array $backendOptions (optional) Array of backend options
+     * @param array<mixed> $backendOptions (optional) Array of backend options
      * @return CacheInterface
      * @throws InvalidBackendException
      */
diff --git a/Neos.Eel/Classes/CompilingEvaluator.php b/Neos.Eel/Classes/CompilingEvaluator.php
index f2d8200285..e322fe03b1 100644
--- a/Neos.Eel/Classes/CompilingEvaluator.php
+++ b/Neos.Eel/Classes/CompilingEvaluator.php
@@ -39,7 +39,7 @@ class CompilingEvaluator implements EelEvaluatorInterface
      *
      * @param StringFrontend $expressionCache
      */
-    public function injectExpressionCache(StringFrontend $expressionCache)
+    public function injectExpressionCache(StringFrontend $expressionCache): void
     {
         $this->expressionCache = $expressionCache;
     }
diff --git a/Neos.Eel/Classes/Context.php b/Neos.Eel/Classes/Context.php
index c4c9cc80e1..4b916380b3 100644
--- a/Neos.Eel/Classes/Context.php
+++ b/Neos.Eel/Classes/Context.php
@@ -58,7 +58,7 @@ public function get($path)
             if (is_array($this->value)) {
                 return array_key_exists($path, $this->value) ? $this->value[$path] : null;
             } elseif (is_object($this->value)) {
-                $this->tracer?->recordPropertyAccess($this->value, $path);
+                $this->tracer?->recordPropertyAccess($this->value, (string)$path);
                 try {
                     return ObjectAccess::getProperty($this->value, $path);
                 } catch (PropertyNotAccessibleException $exception) {
@@ -73,19 +73,19 @@ public function get($path)
     /**
      * Get a value by path and wrap it into another context
      *
-     * @param string $path
+     * @param ?string $path
      * @return Context The wrapped value
      */
     public function getAndWrap($path = null)
     {
-        return $this->wrap($this->get($path));
+        return $this->wrap($this->get($path ?: '') ?: '');
     }
 
     /**
      * Call a method on this context
      *
      * @param string $method
-     * @param array $arguments Arguments to the method, if of type Context they will be unwrapped
+     * @param array<mixed> $arguments Arguments to the method, if of type Context they will be unwrapped
      * @return mixed
      * @throws \Exception
      */
@@ -127,7 +127,7 @@ public function call($method, array $arguments = [])
      * Call a method and wrap the result
      *
      * @param string $method
-     * @param array $arguments
+     * @param array<mixed> $arguments
      * @return mixed
      */
     public function callAndWrap($method, array $arguments = [])
diff --git a/Neos.Eel/Classes/FlowQuery/FlowQuery.php b/Neos.Eel/Classes/FlowQuery/FlowQuery.php
index a78491bc6f..f7dfa4a2f4 100644
--- a/Neos.Eel/Classes/FlowQuery/FlowQuery.php
+++ b/Neos.Eel/Classes/FlowQuery/FlowQuery.php
@@ -71,13 +71,17 @@
  * If an operation is final, it should return the resulting value directly.
  *
  * @phpstan-consistent-constructor
+ *
+ * @phpstan-type Operation array{name: string, arguments: array<mixed>}
+ *
+ * @implements \IteratorAggregate<mixed>
  */
 class FlowQuery implements ProtectedContextAwareInterface, \IteratorAggregate, \Countable
 {
     /**
      * the objects this FlowQuery object wraps
      *
-     * @var array|\Traversable
+     * @var array<mixed>|\Traversable<mixed>
      */
     protected $context;
 
@@ -87,7 +91,7 @@ class FlowQuery implements ProtectedContextAwareInterface, \IteratorAggregate, \
      * whereas the name is a string like 'children' and the arguments
      * are a numerically-indexed array
      *
-     * @var array
+     * @var array<int,Operation>
      */
     protected $operations = [];
 
@@ -104,16 +108,12 @@ class FlowQuery implements ProtectedContextAwareInterface, \IteratorAggregate, \
      *
      * If a FlowQuery is given as the $context we unwrap its context to assert q(q(context)) == q(context).
      *
-     * @param array|\Traversable $context The initial context (wrapped objects) for this FlowQuery
-     * @param array              $operations
-     * @throws Exception
+     * @param array<mixed>|\Traversable<mixed> $context The initial context (wrapped objects) for this FlowQuery
+     * @param array<int,Operation> $operations
      * @api
      */
     public function __construct($context, array $operations = [])
     {
-        if (!(is_array($context) || $context instanceof \Traversable)) {
-            throw new Exception('The FlowQuery context must be an array or implement \Traversable but context was a ' . gettype($context), 1380816689);
-        }
         if ($context instanceof FlowQuery) {
             $this->context = $context->getContext();
         } else {
@@ -139,7 +139,7 @@ public static function q($element): self
      *
      * @param OperationResolverInterface $operationResolver
      */
-    public function setOperationResolver(OperationResolverInterface $operationResolver)
+    public function setOperationResolver(OperationResolverInterface $operationResolver): void
     {
         $this->operationResolver = $operationResolver;
     }
@@ -150,7 +150,7 @@ public function setOperationResolver(OperationResolverInterface $operationResolv
      * If the operation is final, we directly compute the result and return the value.
      *
      * @param string $operationName
-     * @param array $arguments
+     * @param array<mixed> $arguments
      * @return FlowQuery|mixed
      */
     public function __call($operationName, array $arguments)
@@ -194,14 +194,14 @@ public function count(): int
      *
      * Should NEVER be called inside an operation!
      *
-     * @return \ArrayIterator
+     * @return \ArrayIterator<int|string, mixed>
      */
     public function getIterator(): \ArrayIterator
     {
         if (count($this->operations) > 0) {
             $this->evaluateOperations();
         }
-        return new \ArrayIterator($this->context);
+        return new \ArrayIterator($this->context instanceof \Traversable ? iterator_to_array($this->context) : $this->context);
     }
 
     /**
@@ -227,7 +227,7 @@ protected function evaluateOperations()
      *
      * Should only be called inside an operation.
      *
-     * @return array
+     * @return Operation|null
      */
     public function popOperation()
     {
@@ -242,9 +242,9 @@ public function popOperation()
      * Should only be called inside an operation.
      *
      * @param string $operationName
-     * @param array $arguments
+     * @param array<mixed> $arguments
      */
-    public function pushOperation($operationName, array $arguments)
+    public function pushOperation($operationName, array $arguments): void
     {
         array_unshift($this->operations, [
             'name' => $operationName,
@@ -273,7 +273,7 @@ public function peekOperationName()
      *
      * Should only be called inside an operation.
      *
-     * @return array|\Traversable
+     * @return array<mixed>|\Traversable<mixed>
      */
     public function getContext()
     {
@@ -285,9 +285,9 @@ public function getContext()
      *
      * Should only be called inside an operation.
      *
-     * @param array|\Traversable $context
+     * @param array<mixed>|\Traversable<mixed> $context
      */
-    public function setContext($context)
+    public function setContext($context): void
     {
         $this->context = $context;
     }
diff --git a/Neos.Eel/Classes/FlowQuery/OperationInterface.php b/Neos.Eel/Classes/FlowQuery/OperationInterface.php
index fed593f28f..981e7c1260 100644
--- a/Neos.Eel/Classes/FlowQuery/OperationInterface.php
+++ b/Neos.Eel/Classes/FlowQuery/OperationInterface.php
@@ -42,7 +42,7 @@ public static function isFinal();
      * can work with the $context objects. It can be implemented
      * to implement runtime conditions.
      *
-     * @param array $context (or array-like object) $context onto which this operation should be applied
+     * @param array<mixed>|\Traversable<mixed> $context (or array-like object) $context onto which this operation should be applied
      * @return boolean true if the operation can be applied onto the $context, false otherwise
      * @api
      */
@@ -57,7 +57,7 @@ public function canEvaluate($context);
      * If the operation is final, evaluate should directly return the operation result.
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments the arguments for this operation
+     * @param array<mixed> $arguments the arguments for this operation
      * @return mixed if the operation is final, the return value
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments);
diff --git a/Neos.Eel/Classes/FlowQuery/OperationResolver.php b/Neos.Eel/Classes/FlowQuery/OperationResolver.php
index ce8685de32..b61c0d969e 100644
--- a/Neos.Eel/Classes/FlowQuery/OperationResolver.php
+++ b/Neos.Eel/Classes/FlowQuery/OperationResolver.php
@@ -38,7 +38,7 @@ class OperationResolver implements OperationResolverInterface
      * 2-dimensional array of registered operations:
      * shortOperationName => priority => operation class name
      *
-     * @var array
+     * @var array<string,array<int,string>>
      */
     protected $operations = [];
 
@@ -46,14 +46,14 @@ class OperationResolver implements OperationResolverInterface
      * associative array of registered final operations:
      * shortOperationName => shortOperationName
      *
-     * @var array
+     * @var array<string,string>
      */
     protected $finalOperationNames = [];
 
     /**
      * Initializer, building up $this->operations and $this->finalOperationNames
      */
-    public function initializeObject()
+    public function initializeObject(): void
     {
         $operationsAndFinalOperationNames = static::buildOperationsAndFinalOperationNames($this->objectManager);
         $this->operations = $operationsAndFinalOperationNames[0];
@@ -62,7 +62,7 @@ public function initializeObject()
 
     /**
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of sorted operations and array of final operation names
+     * @return array{0: array<mixed>, 1: array<mixed>} Array of sorted operations and array of final operation names
      * @throws FlowQueryException
      * @Flow\CompileStatic
      */
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/AbstractOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/AbstractOperation.php
index a2527ce36f..0a9e2a3f43 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/AbstractOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/AbstractOperation.php
@@ -80,7 +80,7 @@ public static function getShortName()
     /**
      * {@inheritdoc}
      *
-     * @param array $context (or array-like object) $context onto which this operation should be applied
+     * @param array<mixed> $context (or array-like object) $context onto which this operation should be applied
      * @return boolean true if the operation can be applied onto the $context, false otherwise
      * @api
      */
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/AddOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/AddOperation.php
index de8f2e0d44..535ad4b64c 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/AddOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/AddOperation.php
@@ -31,7 +31,7 @@ class AddOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments the elements to add (as array in index 0)
+     * @param array<mixed> $arguments the elements to add (as array in index 0)
      * @return void
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/CountOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/CountOperation.php
index 5626d58242..a74f285a43 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/CountOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/CountOperation.php
@@ -38,13 +38,15 @@ class CountOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments filter arguments for this operation
+     * @param array<mixed> $arguments filter arguments for this operation
      * @return void|integer with the number of elements
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
     {
         if (count($arguments) == 0) {
-            return count($flowQuery->getContext());
+            $context = $flowQuery->getContext();
+            $context = $context instanceof \Traversable ? iterator_to_array($context) : $context;
+            return count($context);
         } else {
             $flowQuery->pushOperation('count', []);
             $flowQuery->pushOperation('filter', $arguments);
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/FirstOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/FirstOperation.php
index 2f7e9f6685..4686e010ff 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/FirstOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/FirstOperation.php
@@ -29,12 +29,13 @@ class FirstOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments Ignored for this operation
+     * @param array<mixed> $arguments Ignored for this operation
      * @return void
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
     {
         $context = $flowQuery->getContext();
+        $context = $context instanceof \Traversable ? iterator_to_array($context) : $context;
         if (isset($context[0])) {
             $flowQuery->setContext([$context[0]]);
         } else {
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/GetOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/GetOperation.php
index d3404b9463..a116d071a7 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/GetOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/GetOperation.php
@@ -44,12 +44,13 @@ class GetOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments the context index to fetch from
+     * @param array<mixed> $arguments the context index to fetch from
      * @return mixed
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
     {
         $context = $flowQuery->getContext();
+        $context = $context instanceof \Traversable ? iterator_to_array($context) : $context;
         if (isset($arguments[0])) {
             $index = $arguments[0];
             if (isset($context[$index])) {
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/IsOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/IsOperation.php
index 336af81685..bf828d1b28 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/IsOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/IsOperation.php
@@ -39,13 +39,15 @@ class IsOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments the filter arguments
+     * @param array<mixed> $arguments the filter arguments
      * @return mixed
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
     {
         if (count($arguments) == 0) {
-            return count($flowQuery->getContext()) > 0;
+            $context = $flowQuery->getContext();
+            $context = $context instanceof \Traversable ? iterator_to_array($context) : $context;
+            return count($context) > 0;
         } else {
             $flowQuery->pushOperation('is', []);
             $flowQuery->pushOperation('filter', $arguments);
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/LastOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/LastOperation.php
index f5cfd87b5a..784202cc6f 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/LastOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/LastOperation.php
@@ -29,12 +29,13 @@ class LastOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments Ignored for this operation
+     * @param array<mixed> $arguments Ignored for this operation
      * @return void
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
     {
         $context = $flowQuery->getContext();
+        $context = $context instanceof \Traversable ? iterator_to_array($context) : $context;
         if (count($context) > 0) {
             $flowQuery->setContext([end($context)]);
         } else {
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/Object/ChildrenOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/Object/ChildrenOperation.php
index 8517220949..c73509e2be 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/Object/ChildrenOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/Object/ChildrenOperation.php
@@ -36,19 +36,24 @@ class ChildrenOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments the filter expression to use (in index 0)
+     * @param array<mixed> $arguments the filter expression to use (in index 0)
      * @return void
      * @throws FizzleException
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
     {
-        if (count($flowQuery->getContext()) === 0) {
+        $context = $flowQuery->getContext();
+        $context = $context instanceof \Traversable ? iterator_to_array($context) : $context;
+        if (count($context) === 0) {
             return;
         }
 
         if (!isset($arguments[0]) || empty($arguments[0])) {
             if ($flowQuery->peekOperationName() === 'filter') {
                 $filterOperation = $flowQuery->popOperation();
+                if ($filterOperation === null) {
+                    throw new FizzleException('Could not resolve filter operation', 1744532569);
+                }
                 if (count($filterOperation['arguments']) === 0 || empty($filterOperation['arguments'][0])) {
                     throw new FizzleException('Filter() needs arguments if it follows an empty children(): children().filter()', 1332489382);
                 }
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/Object/FilterOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/Object/FilterOperation.php
index fe4ccee930..14112c0a1e 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/Object/FilterOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/Object/FilterOperation.php
@@ -87,7 +87,7 @@ class FilterOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments the filter expression to use (in index 0)
+     * @param array<mixed> $arguments the filter expression to use (in index 0)
      * @return void
      * @throws FizzleException
      */
@@ -120,7 +120,7 @@ public function evaluate(FlowQuery $flowQuery, array $arguments)
      * Filter Group is something like "[foo], [bar]"
      *
      * @param object $element
-     * @param array $parsedFilter
+     * @param array<string,mixed> $parsedFilter
      * @return boolean true if $element matches filter group, false otherwise
      */
     protected function matchesFilterGroup($element, array $parsedFilter)
@@ -138,7 +138,7 @@ protected function matchesFilterGroup($element, array $parsedFilter)
      * Match a single filter, i.e. [foo]. It matches only if all filter parts match.
      *
      * @param object $element
-     * @param string $filter
+     * @param array<string,mixed> $filter
      * @return boolean true if $element matches filter, false otherwise
      */
     protected function matchesFilter($element, $filter)
@@ -177,7 +177,7 @@ protected function matchesPropertyNameFilter($element, $propertyNameFilter)
      * Match a single attribute filter
      *
      * @param mixed $element
-     * @param array $attributeFilter
+     * @param array<mixed> $attributeFilter
      * @return boolean
      */
     protected function matchesAttributeFilter($element, array $attributeFilter)
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/Object/PropertyOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/Object/PropertyOperation.php
index d3d0b1ac41..8b598d2078 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/Object/PropertyOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/Object/PropertyOperation.php
@@ -43,7 +43,7 @@ class PropertyOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments the property path to use (in index 0)
+     * @param array<mixed> $arguments the property path to use (in index 0)
      * @return mixed
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
@@ -53,6 +53,7 @@ public function evaluate(FlowQuery $flowQuery, array $arguments)
         }
 
         $context = $flowQuery->getContext();
+        $context = $context instanceof \Traversable ? iterator_to_array($context) : $context;
         if (!isset($context[0])) {
             return null;
         }
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/RemoveOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/RemoveOperation.php
index 7999975bc3..c05dfcec0f 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/RemoveOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/RemoveOperation.php
@@ -31,7 +31,7 @@ class RemoveOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments the elements to remove (as array in index 0)
+     * @param array<mixed> $arguments the elements to remove (as array in index 0)
      * @return void
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
@@ -46,8 +46,9 @@ public function evaluate(FlowQuery $flowQuery, array $arguments)
                 $valuesToRemove[] = $arguments[0];
             }
         }
+        $context = $flowQuery->getContext();
         $filteredContext = array_filter(
-            $flowQuery->getContext(),
+            $context instanceof \Traversable ? iterator_to_array($context) : $context,
             function ($item) use ($valuesToRemove) {
                 return in_array($item, $valuesToRemove, true) === false;
             }
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/SliceOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/SliceOperation.php
index 16201f6de3..c5d71c7e8e 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/SliceOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/SliceOperation.php
@@ -32,13 +32,13 @@ class SliceOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments A mandatory start and optional end index in the context, negative indices indicate an offset from the start or end respectively
+     * @param array<mixed> $arguments A mandatory start and optional end index in the context, negative indices indicate an offset from the start or end respectively
      * @return void
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
     {
         $context = $flowQuery->getContext();
-        if ($context instanceof \Iterator) {
+        if ($context instanceof \Traversable) { /** @todo fix me in 8.3+ */
             $context = iterator_to_array($context);
         }
         if (isset($arguments[0]) && isset($arguments[1])) {
diff --git a/Neos.Eel/Classes/FlowQuery/Operations/UniqueOperation.php b/Neos.Eel/Classes/FlowQuery/Operations/UniqueOperation.php
index e849455cd1..20dbd0f3f6 100644
--- a/Neos.Eel/Classes/FlowQuery/Operations/UniqueOperation.php
+++ b/Neos.Eel/Classes/FlowQuery/Operations/UniqueOperation.php
@@ -29,7 +29,7 @@ class UniqueOperation extends AbstractOperation
      * {@inheritdoc}
      *
      * @param FlowQuery $flowQuery the FlowQuery object
-     * @param array $arguments the elements to remove (as array in index 0)
+     * @param array<mixed> $arguments the elements to remove (as array in index 0)
      * @return void
      */
     public function evaluate(FlowQuery $flowQuery, array $arguments)
diff --git a/Neos.Eel/Classes/Helper/ArrayHelper.php b/Neos.Eel/Classes/Helper/ArrayHelper.php
index ad7936a75b..d979839372 100644
--- a/Neos.Eel/Classes/Helper/ArrayHelper.php
+++ b/Neos.Eel/Classes/Helper/ArrayHelper.php
@@ -33,7 +33,7 @@ class ArrayHelper implements ProtectedContextAwareInterface
      * @param iterable|mixed $array1 First array or value
      * @param iterable|mixed $array2 Second array or value
      * @param iterable|mixed $array_ Optional variable list of additional arrays / values
-     * @return array The array with concatenated arrays or values
+     * @return array<mixed> The array with concatenated arrays or values
      */
     public function concat($array1, $array2, $array_ = null): array
     {
@@ -51,7 +51,7 @@ public function concat($array1, $array2, $array_ = null): array
     /**
      * Join values of an array with a separator
      *
-     * @param iterable $array Array with values to join
+     * @param iterable<mixed> $array Array with values to join
      * @param string $separator A separator for the values
      * @return string A string with the joined values separated by the separator
      */
@@ -66,10 +66,10 @@ public function join(iterable $array, $separator = ','): string
     /**
      * Extract a portion of an indexed array
      *
-     * @param iterable $array The array (with numeric indices)
+     * @param iterable<mixed> $array The array (with numeric indices)
      * @param int $begin
      * @param int $end
-     * @return array
+     * @return array<mixed>
      */
     public function slice(iterable $array, $begin, $end = null): array
     {
@@ -88,8 +88,8 @@ public function slice(iterable $array, $begin, $end = null): array
     /**
      * Returns an array in reverse order
      *
-     * @param iterable $array The array
-     * @return array
+     * @param iterable<mixed> $array The array
+     * @return array<mixed>
      */
     public function reverse(iterable $array): array
     {
@@ -102,8 +102,8 @@ public function reverse(iterable $array): array
     /**
      * Get the array keys
      *
-     * @param iterable $array The array
-     * @return array
+     * @param iterable<mixed> $array The array
+     * @return array<mixed>
      */
     public function keys(iterable $array): array
     {
@@ -116,8 +116,8 @@ public function keys(iterable $array): array
     /**
      * Get the array values
      *
-     * @param iterable $array The array
-     * @return array
+     * @param iterable<mixed> $array The array
+     * @return array<mixed>
      */
     public function values(iterable $array): array
     {
@@ -130,7 +130,7 @@ public function values(iterable $array): array
     /**
      * Get the length of an array
      *
-     * @param iterable $array The array
+     * @param iterable<mixed> $array The array
      * @return int
      */
     public function length(iterable $array): int
@@ -144,7 +144,7 @@ public function length(iterable $array): int
     /**
      * Check if an array is empty
      *
-     * @param iterable $array The array
+     * @param iterable<mixed> $array The array
      * @return bool true if the array is empty
      */
     public function isEmpty(iterable $array): bool
@@ -155,7 +155,7 @@ public function isEmpty(iterable $array): bool
     /**
      * Get the first element of an array
      *
-     * @param iterable $array The array
+     * @param iterable<mixed> $array The array
      * @return mixed
      */
     public function first(iterable $array)
@@ -172,7 +172,7 @@ public function first(iterable $array)
     /**
      * Get the last element of an array
      *
-     * @param iterable $array The array
+     * @param iterable<mixed> $array The array
      * @return mixed
      */
     public function last(iterable $array)
@@ -191,7 +191,7 @@ public function last(iterable $array)
      * Returns the first index at which a given element can be found in the array,
      * or -1 if it is not present
      *
-     * @param iterable $array The array
+     * @param iterable<mixed> $array The array
      * @param mixed $searchElement The element value to find
      * @param int $fromIndex Position in the array to start the search.
      * @return int
@@ -217,7 +217,7 @@ public function indexOf(iterable $array, $searchElement, $fromIndex = null): int
     /**
      * Picks a random element from the array
      *
-     * @param array $array
+     * @param array<mixed> $array
      * @return mixed A random entry or null if the array is empty
      */
     public function random(iterable $array)
@@ -240,8 +240,8 @@ public function random(iterable $array)
      * Internally natsort() is used as it most closely resembles javascript's sort().
      * Because there are no real associative arrays in Javascript, keys of the array will be preserved.
      *
-     * @param iterable $array
-     * @return array The sorted array
+     * @param iterable<mixed> $array
+     * @return array<mixed> The sorted array
      */
     public function sort(iterable $array): array
     {
@@ -268,8 +268,8 @@ public function sort(iterable $array): array
     /**
      * Sort an array by key
      *
-     * @param iterable $array The array to sort
-     * @return array The sorted array
+     * @param iterable<mixed> $array The array to sort
+     * @return array<mixed> The sorted array
      */
     public function ksort(iterable $array): array
     {
@@ -286,9 +286,9 @@ public function ksort(iterable $array): array
      * Randomizes entries an array with the option to preserve the existing keys.
      * When this option is set to false, all keys will be replaced
      *
-     * @param iterable $array
-     * @param bool $preserveKeys Wether to preserve the keys when shuffling the array
-     * @return array The shuffled array
+     * @param iterable<mixed> $array
+     * @param bool $preserveKeys Whether to preserve the keys when shuffling the array
+     * @return array<mixed> The shuffled array
      */
     public function shuffle(iterable $array, $preserveKeys = true): array
     {
@@ -315,8 +315,8 @@ public function shuffle(iterable $array, $preserveKeys = true): array
     /**
      * Removes duplicate values from an array
      *
-     * @param iterable $array The input array
-     * @return array The filtered array.
+     * @param iterable<mixed> $array The input array
+     * @return array<mixed> The filtered array.
      */
     public function unique(iterable $array): array
     {
@@ -333,8 +333,8 @@ public function unique(iterable $array): array
      *
      * An empty array will result in an empty array again.
      *
-     * @param iterable $array
-     * @return array The array without the last element
+     * @param iterable<mixed> $array
+     * @return array<mixed> The array without the last element
      */
     public function pop(iterable $array): array
     {
@@ -355,9 +355,9 @@ public function pop(iterable $array): array
      *
      *     Array.push(array, e1, e2)
      *
-     * @param iterable|scalar|null $array
+     * @param mixed $array
      * @param mixed $element
-     * @return array The array with the inserted elements
+     * @return array<mixed> The array with the inserted elements
      */
     public function push($array, $element): array
     {
@@ -388,8 +388,8 @@ public function push($array, $element): array
      *
      * An empty array will result in an empty array again.
      *
-     * @param iterable $array
-     * @return array The array without the first element
+     * @param iterable<mixed> $array
+     * @return array<mixed> The array without the first element
      */
     public function shift(iterable $array): array
     {
@@ -407,9 +407,9 @@ public function shift(iterable $array): array
      *
      *     Array.unshift(array, e1, e2)
      *
-     * @param iterable $array
+     * @param iterable<mixed> $array
      * @param mixed $element
-     * @return array The array with the inserted elements
+     * @return array<mixed> The array with the inserted elements
      */
     public function unshift(iterable $array, $element): array
     {
@@ -432,11 +432,11 @@ public function unshift(iterable $array, $element): array
      *
      *     Array.splice(array, 3, 2, 'a', 'b')
      *
-     * @param iterable $array
+     * @param iterable<mixed> $array
      * @param int $offset Index of the first element to remove
      * @param int $length Number of elements to remove
      * @param mixed $replacements Elements to insert instead of the removed range
-     * @return array The array with removed and replaced elements
+     * @return array<mixed> The array with removed and replaced elements
      */
     public function splice(iterable $array, $offset, $length = 1, $replacements = null): array
     {
@@ -455,8 +455,8 @@ public function splice(iterable $array, $offset, $length = 1, $replacements = nu
      * Note that the values of array need to be valid keys, i.e. they need to be either int or string.
      * If a value has several occurrences, the latest key will be used as its value, and all others will be lost.
      *
-     * @param iterable $array
-     * @return array The array with flipped keys and values
+     * @param iterable<mixed> $array
+     * @return array<mixed> The array with flipped keys and values
      */
     public function flip(iterable $array): array
     {
@@ -475,7 +475,7 @@ public function flip(iterable $array): array
      * @param mixed $start First value of the sequence.
      * @param mixed $end The sequence is ended upon reaching the end value.
      * @param int $step The increment between items, will default to 1.
-     * @return array Array of elements from start to end, inclusive.
+     * @return array<mixed> Array of elements from start to end, inclusive.
      */
     public function range($start, $end, $step = 1): array
     {
@@ -485,10 +485,10 @@ public function range($start, $end, $step = 1): array
     /**
      * Set the specified key in the the array
      *
-     * @param iterable $array
+     * @param iterable<mixed> $array
      * @param string|integer $key the key that should be set
      * @param mixed $value the value to assign to the key
-     * @return array The modified array.
+     * @return array<mixed> The modified array.
      */
     public function set(iterable $array, $key, $value): array
     {
@@ -507,9 +507,9 @@ public function set(iterable $array, $key, $value): array
      *     Array.map([1, 2, 3, 4], x => x * x)
      *     Array.map([1, 2, 3, 4], (x, index) => x * index)
      *
-     * @param iterable $array Array of elements to map
+     * @param iterable<mixed> $array Array of elements to map
      * @param callable $callback Callback to apply for each element, current value and key will be passed as arguments
-     * @return array The array with callback applied, keys will be preserved
+     * @return array<mixed> The array with callback applied, keys will be preserved
      */
     public function map(iterable $array, callable $callback): array
     {
@@ -528,7 +528,7 @@ public function map(iterable $array, callable $callback): array
      *     Array.reduce([1, 2, 3, 4], (accumulator, currentValue) => accumulator + currentValue) // == 10
      *     Array.reduce([1, 2, 3, 4], (accumulator, currentValue) => accumulator + currentValue, 1) // == 11
      *
-     * @param iterable $array Array of elements to reduce to a value
+     * @param iterable<mixed> $array Array of elements to reduce to a value
      * @param callable $callback Callback for accumulating values, accumulator, current value and key will be passed as arguments
      * @param mixed $initialValue Initial value, defaults to first item in array and callback starts with second entry
      * @return mixed
@@ -558,9 +558,9 @@ public function reduce(iterable $array, callable $callback, $initialValue = null
      *     Array.filter([1, 2, 3, 4], x => x % 2 == 0) // == [2, 4]
      *     Array.filter(['foo', 'bar', 'baz'], (x, index) => index < 2) // == ['foo', 'bar']
      *
-     * @param iterable $array Array of elements to filter
-     * @param callable $callback Callback for testing if an element should be included in the result, current value and key will be passed as arguments
-     * @return array The array with elements where callback returned true
+     * @param iterable<mixed> $array Array of elements to filter
+     * @param ?callable $callback Callback for testing if an element should be included in the result, current value and key will be passed as arguments
+     * @return array<mixed> The array with elements where callback returned true
      */
     public function filter(iterable $array, ?callable $callback = null): array
     {
@@ -583,7 +583,7 @@ public function filter(iterable $array, ?callable $callback = null): array
      *     Array.some([1, 2, 3, 4], x => x % 2 == 0) // == true
      *     Array.some([1, 2, 3, 4], x => x > 4) // == false
      *
-     * @param iterable $array Array of elements to test
+     * @param iterable<mixed> $array Array of elements to test
      * @param callable $callback Callback for testing elements, current value and key will be passed as arguments
      * @return bool True if at least one element passed the test
      */
@@ -606,7 +606,7 @@ public function some(iterable $array, callable $callback): bool
      *     Array.every([1, 2, 3, 4], x => x % 2 == 0) // == false
      *     Array.every([2, 4, 6, 8], x => x % 2) // == true
      *
-     * @param iterable $array Array of elements to test
+     * @param iterable<mixed> $array Array of elements to test
      * @param callable $callback Callback for testing elements, current value and key will be passed as arguments
      * @return bool True if all elements passed the test
      */
diff --git a/Neos.Eel/Classes/Helper/DateHelper.php b/Neos.Eel/Classes/Helper/DateHelper.php
index 8d9bec997c..76e3423a91 100644
--- a/Neos.Eel/Classes/Helper/DateHelper.php
+++ b/Neos.Eel/Classes/Helper/DateHelper.php
@@ -41,7 +41,7 @@ class DateHelper implements ProtectedContextAwareInterface
      *
      * @param string $string
      * @param string $format
-     * @return \DateTime
+     * @return \DateTime|false
      */
     public function parse($string, $format)
     {
diff --git a/Neos.Eel/Classes/Helper/FileHelper.php b/Neos.Eel/Classes/Helper/FileHelper.php
index 5da04592ce..debac9393b 100644
--- a/Neos.Eel/Classes/Helper/FileHelper.php
+++ b/Neos.Eel/Classes/Helper/FileHelper.php
@@ -27,7 +27,7 @@ class FileHelper implements ProtectedContextAwareInterface
      */
     public function readFile(string $filepath): string
     {
-        return file_get_contents($filepath);
+        return file_get_contents($filepath) ?: '';
     }
 
     /**
@@ -36,14 +36,14 @@ public function readFile(string $filepath): string
      */
     public function getSha1(string $filepath): string
     {
-        return sha1_file($filepath);
+        return sha1_file($filepath) ?: '';
     }
 
     /**
      * Get file name and path information
      *
      * @param string $filepath
-     * @return array with keys dirname, basename, extension (if any), and filename
+     * @return array<mixed> with keys dirname, basename, extension (if any), and filename
      */
     public function fileInfo(string $filepath)
     {
@@ -54,11 +54,11 @@ public function fileInfo(string $filepath)
      * Get file information like creation and modification times as well as size.
      *
      * @param string $filepath
-     * @return array with keys mode, uid, gid, size, atime, mtime, ctime, (blksize, blocks, dev, ino, nlink, rdev)
+     * @return array<mixed> with keys mode, uid, gid, size, atime, mtime, ctime, (blksize, blocks, dev, ino, nlink, rdev)
      */
     public function stat(string $filepath)
     {
-        return stat($filepath);
+        return stat($filepath) ?: [];
     }
 
     /**
@@ -71,7 +71,7 @@ public function exists(string $filepath): bool
     {
         return file_exists($filepath);
     }
-    
+
     /**
      * @param string $methodName
      * @return bool
diff --git a/Neos.Eel/Classes/Helper/JsonHelper.php b/Neos.Eel/Classes/Helper/JsonHelper.php
index 1198033e1d..d95ff70994 100644
--- a/Neos.Eel/Classes/Helper/JsonHelper.php
+++ b/Neos.Eel/Classes/Helper/JsonHelper.php
@@ -29,13 +29,14 @@ class JsonHelper implements ProtectedContextAwareInterface
      * Json.stringify(value, ['JSON_UNESCAPED_UNICODE', 'JSON_FORCE_OBJECT'])
      *
      * @param mixed $value
-     * @param array $options Array of option constant names as strings
+     * @param array<int> $options Array of option constant names as strings
      * @return string
      */
     public function stringify($value, array $options = []): string
     {
+        /** @phpstan-ignore argument.type ("constant" is callable) */
         $optionSum = array_sum(array_map('constant', $options));
-        return json_encode($value, $optionSum);
+        return json_encode($value, $optionSum | JSON_THROW_ON_ERROR);
     }
 
     /**
diff --git a/Neos.Eel/Classes/Helper/MathHelper.php b/Neos.Eel/Classes/Helper/MathHelper.php
index 1d6de50619..a659aa7f88 100644
--- a/Neos.Eel/Classes/Helper/MathHelper.php
+++ b/Neos.Eel/Classes/Helper/MathHelper.php
@@ -91,7 +91,7 @@ public function getSQRT2()
     }
 
     /**
-     * @param float $x A number
+     * @param mixed $x A number
      * @return float The absolute value of the given value
      */
     public function abs($x = NAN)
@@ -243,7 +243,7 @@ public function floor($x)
      */
     public function isFinite($x)
     {
-        return is_numeric($x) && is_finite($x);
+        return is_numeric($x) && is_finite((float)$x);
     }
 
     /**
@@ -256,7 +256,7 @@ public function isFinite($x)
      */
     public function isInfinite($x)
     {
-        return is_numeric($x) && is_infinite($x);
+        return is_numeric($x) && is_infinite((float)$x);
     }
 
     /**
@@ -269,7 +269,7 @@ public function isInfinite($x)
      */
     public function isNaN($x)
     {
-        return !is_numeric($x) || is_nan($x);
+        return !is_numeric($x) || is_nan((float)$x);
     }
 
     /**
@@ -402,7 +402,7 @@ public function randomInt($min, $max)
      * Negative values are also supported (-1 rounds to full 10ths).
      *
      * @param mixed $subject The value to round
-     * @param integer $precision The precision (digits after decimal point) to use, defaults to 0
+     * @param mixed $precision The precision (digits after decimal point) to use, defaults to 0
      * @return float The rounded value
      */
     public function round($subject, $precision = 0)
@@ -411,7 +411,7 @@ public function round($subject, $precision = 0)
             return NAN;
         }
         $subject = (float)$subject;
-        if ($precision !== null && !is_int($precision)) {
+        if (!is_int($precision)) {
             return NAN;
         }
         return round($subject, (int)$precision);
@@ -420,7 +420,7 @@ public function round($subject, $precision = 0)
     /**
      * Get the sign of the given number, indicating whether the number is positive, negative or zero
      *
-     * @param integer|float $x The value
+     * @param mixed $x The value
      * @return integer|float -1, 0, 1 depending on the sign or NAN if the given value was not numeric
      */
     public function sign($x)
diff --git a/Neos.Eel/Classes/Helper/SecurityHelper.php b/Neos.Eel/Classes/Helper/SecurityHelper.php
index 94400c3d14..8d75cd1473 100644
--- a/Neos.Eel/Classes/Helper/SecurityHelper.php
+++ b/Neos.Eel/Classes/Helper/SecurityHelper.php
@@ -80,7 +80,7 @@ public function isAuthenticated(): bool
      * Returns true, if access to the given privilege-target is granted
      *
      * @param string $privilegeTarget The identifier of the privilege target to decide on
-     * @param array $parameters Optional array of privilege parameters (simple key => value array)
+     * @param array<mixed> $parameters Optional array of privilege parameters (simple key => value array)
      * @return boolean true if access is granted, false otherwise
      */
     public function hasAccess(string $privilegeTarget, array $parameters = []): bool
diff --git a/Neos.Eel/Classes/Helper/StringHelper.php b/Neos.Eel/Classes/Helper/StringHelper.php
index 79b28dc035..f9ca953db7 100755
--- a/Neos.Eel/Classes/Helper/StringHelper.php
+++ b/Neos.Eel/Classes/Helper/StringHelper.php
@@ -230,7 +230,7 @@ public function lastIndexOf($string, $search, $toIndex = null)
      *
      * @param string $string The input string
      * @param string $pattern A PREG pattern
-     * @return array|null The matches as array or NULL if not matched
+     * @return array<mixed>|null The matches as array or NULL if not matched
      * @throws EvaluationException
      */
     public function pregMatch($string, $pattern)
@@ -255,7 +255,7 @@ public function pregMatch($string, $pattern)
      *
      * @param string $string The input string
      * @param string $pattern A PREG pattern
-     * @return array|null The matches as array or NULL if not matched
+     * @return array<mixed>|null The matches as array or NULL if not matched
      * @throws EvaluationException
      */
     public function pregMatchAll($string, $pattern)
@@ -287,10 +287,7 @@ public function pregMatchAll($string, $pattern)
      */
     public function pregReplace($string, $pattern, $replace, $limit = -1)
     {
-        if ($limit === null) {
-            $limit = -1;
-        }
-        return preg_replace($pattern, $replace, (string)$string, $limit);
+        return preg_replace($pattern, $replace, (string)$string, $limit) ?: '';
     }
 
     /**
@@ -304,11 +301,11 @@ public function pregReplace($string, $pattern, $replace, $limit = -1)
      * @param string $string The input string
      * @param string $pattern A PREG pattern
      * @param integer $limit The maximum amount of items to return, in contrast to split() this will return all remaining characters in the last item (see example)
-     * @return array An array of the splitted parts, excluding the matched pattern
+     * @return array<string> An array of the splitted parts, excluding the matched pattern
      */
     public function pregSplit($string, $pattern, $limit = -1)
     {
-        return preg_split($pattern, (string)$string, (int)$limit);
+        return preg_split($pattern, (string)$string, (int)$limit) ?: [];
     }
 
     /**
@@ -321,10 +318,10 @@ public function pregSplit($string, $pattern, $limit = -1)
      *
      * Note: this method does not perform regular expression matching, @see pregReplace().
      *
-     * @param array|string|null $string The input string
-     * @param array|string|null $search A search string
-     * @param array|string|null $replace A replacement string
-     * @return array|string|string[] The string with all occurrences replaced
+     * @param array<mixed>|string|null $string The input string
+     * @param array<mixed>|string|null $search A search string
+     * @param array<mixed>|string|null $replace A replacement string
+     * @return array<mixed>|string|string[] The string with all occurrences replaced
      */
     public function replace($string, $search, $replace)
     {
@@ -349,7 +346,7 @@ public function replace($string, $search, $replace)
      * @param string $string The string to split
      * @param string|null $separator The separator where the string should be splitted
      * @param int|null $limit The maximum amount of items to split (exceeding items will be discarded)
-     * @return array An array of the splitted parts, excluding the separators
+     * @return array<string> An array of the split parts, excluding the separators
      */
     public function split($string, $separator = null, $limit = null)
     {
@@ -591,7 +588,7 @@ public function rawUrlDecode($string)
      */
     public function htmlSpecialChars($string, $preserveEntities = false)
     {
-        return htmlspecialchars((string)$string, ENT_NOQUOTES | ENT_HTML401, ini_get("default_charset"), !$preserveEntities);
+        return htmlspecialchars((string)$string, ENT_NOQUOTES | ENT_HTML401, ini_get("default_charset") ?: null, !$preserveEntities);
     }
 
     /**
@@ -711,9 +708,9 @@ public function wordCount($unicodeString)
     {
         $unicodeString = (string)$unicodeString;
 
-        $unicodeString = preg_replace('/[[:punct:][:digit:]]/', '', $unicodeString);
+        $unicodeString = preg_replace('/[[:punct:][:digit:]]/', '', $unicodeString) ?: '';
 
-        return count(preg_split('/[[:space:]]+/', $unicodeString, 0, PREG_SPLIT_NO_EMPTY));
+        return count(preg_split('/[[:space:]]+/', $unicodeString, 0, PREG_SPLIT_NO_EMPTY) ?: []);
     }
 
     /**
@@ -746,7 +743,7 @@ public function base64decode($string, bool $strict = false)
      * @see https://php.net/manual/en/function.vsprintf.php
      *
      * @param string $format A formatting string containing directives
-     * @param array $args An array of values to be inserted according to the formatting string $format
+     * @param array<mixed> $args An array of values to be inserted according to the formatting string $format
      * @return string A string produced according to the formatting string $format
      */
     public function format($format, array $args)
diff --git a/Neos.Eel/Classes/Helper/TypeHelper.php b/Neos.Eel/Classes/Helper/TypeHelper.php
index f15f370e28..9f21514ccd 100644
--- a/Neos.Eel/Classes/Helper/TypeHelper.php
+++ b/Neos.Eel/Classes/Helper/TypeHelper.php
@@ -47,8 +47,8 @@ public function getType($variable)
     /**
      * Get the class name of the given variable or NULL if it wasn't an object
      *
-     * @param object $variable
-     * @return string|NULL
+     * @param mixed $variable
+     * @return class-string|NULL
      */
     public function className($variable)
     {
diff --git a/Neos.Eel/Classes/ProtectedContext.php b/Neos.Eel/Classes/ProtectedContext.php
index d3cc0e87e0..bff5ede663 100644
--- a/Neos.Eel/Classes/ProtectedContext.php
+++ b/Neos.Eel/Classes/ProtectedContext.php
@@ -24,7 +24,7 @@
 class ProtectedContext extends Context
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $allowedMethods = [];
 
@@ -32,7 +32,7 @@ class ProtectedContext extends Context
      * Call a method if it is allowed
      *
      * @param string $method
-     * @param array $arguments
+     * @param array<mixed> $arguments
      * @return mixed|void
      * @throws NotAllowedException
      */
@@ -49,7 +49,7 @@ public function call($method, array $arguments = [])
      *
      * The list of allowed methods for the given path is applied to the new context.
      *
-     * @param string $path
+     * @param ProtectedContext|string|null $path
      * @return Context The wrapped value
      */
     public function getAndWrap($path = null)
@@ -82,7 +82,7 @@ public function getAndWrap($path = null)
      *
      *   $context->allow(array('String.*', 'Array.reverse'));
      *
-     * @param array|string $pathOrMethods
+     * @param array<string>|string $pathOrMethods
      * @return void
      */
     public function allow($pathOrMethods)
diff --git a/Neos.Eel/Classes/Utility.php b/Neos.Eel/Classes/Utility.php
index 1b26575abd..ab7e0b3fe9 100644
--- a/Neos.Eel/Classes/Utility.php
+++ b/Neos.Eel/Classes/Utility.php
@@ -35,8 +35,8 @@ public static function parseEelExpression(string $expression): ?string
      * Get variables from configuration that should be set in the context by default.
      * For example Eel helpers are made available by this.
      *
-     * @param array $configuration An one dimensional associative array of context variable paths mapping to object names
-     * @return array Array with default context variable objects.
+     * @param array<mixed> $configuration An one dimensional associative array of context variable paths mapping to object names
+     * @return array<mixed> Array with default context variable objects.
      */
     public static function getDefaultContextVariables(array $configuration)
     {
@@ -45,6 +45,7 @@ public static function getDefaultContextVariables(array $configuration)
             $currentPathBase = & $defaultContextVariables;
             $variablePathNames = explode('.', $variableName);
             foreach ($variablePathNames as $pathName) {
+                /** @phpstan-ignore isset.offset (not so sure here) */
                 if (!isset($currentPathBase[$pathName])) {
                     $currentPathBase[$pathName] = [];
                 }
@@ -66,15 +67,19 @@ public static function getDefaultContextVariables(array $configuration)
     /**
      * Create a closure to be used as Helper for eel.
      *
-     * @param string $objectConfiguration className followed by two colone and the method name
+     * @param string $objectConfiguration className followed by two colons and the method name
      * @return callable
      */
     private static function createClosureFromConfiguration(string $objectConfiguration): callable
     {
         list($className, $methodName) = explode('::', $objectConfiguration, 2);
-        return function (...$arguments) use ($className, $methodName) {
+        return function (...$arguments) use ($className, $methodName, $objectConfiguration) {
+            $callback = [$className, $methodName];
+            if (!is_callable($callback)) {
+                throw new \InvalidArgumentException($objectConfiguration . ' is not callable', 1744529247);
+            }
             return call_user_func_array(
-                [$className, $methodName],
+                $callback,
                 $arguments
             );
         };
@@ -85,8 +90,8 @@ private static function createClosureFromConfiguration(string $objectConfigurati
      *
      * @param string $expression
      * @param EelEvaluatorInterface $eelEvaluator
-     * @param array $contextVariables
-     * @param array $defaultContextConfiguration
+     * @param array<mixed> $contextVariables
+     * @param array<mixed> $defaultContextConfiguration
      * @return mixed
      * @throws Exception
      */
diff --git a/Neos.Error.Messages/Classes/Message.php b/Neos.Error.Messages/Classes/Message.php
index 67f6464d0c..5f57b6baf3 100644
--- a/Neos.Error.Messages/Classes/Message.php
+++ b/Neos.Error.Messages/Classes/Message.php
@@ -43,7 +43,7 @@ class Message
 
     /**
      * The message arguments. Will be replaced in the message body.
-     * @var array
+     * @var array<mixed>
      */
     protected $arguments = [];
 
@@ -58,7 +58,7 @@ class Message
      *
      * @param string $message An english error message which is used if no other error message can be resolved
      * @param integer|null $code A unique error code
-     * @param array $arguments Array of arguments to be replaced in message
+     * @param array<mixed> $arguments Array of arguments to be replaced in message
      * @param string $title optional title for the message
      * @api
      */
@@ -102,7 +102,7 @@ public function getCode(): int
     }
 
     /**
-     * @return array
+     * @return array<mixed>
      * @api
      */
     public function getArguments(): array
diff --git a/Neos.Error.Messages/Classes/Result.php b/Neos.Error.Messages/Classes/Result.php
index f363a092a8..5a82b0635e 100644
--- a/Neos.Error.Messages/Classes/Result.php
+++ b/Neos.Error.Messages/Classes/Result.php
@@ -128,79 +128,86 @@ public function addNotice(Notice $notice)
     /**
      * Get all errors in the current Result object (non-recursive)
      *
-     * @param string $messageTypeFilter if specified only errors implementing the given class are returned
+     * @template T of Error
+     * @param class-string<T>|null $messageTypeFilter if specified only errors implementing the given class are returned
      * @return array<Error>
      * @api
      */
     public function getErrors(?string $messageTypeFilter = null): array
     {
-        return $this->filterMessages($this->errors, $messageTypeFilter);
+        return $this->filterMessages($this->errors, $messageTypeFilter ?: Error::class);
     }
 
     /**
      * Get all warnings in the current Result object (non-recursive)
      *
-     * @param string $messageTypeFilter if specified only warnings implementing the given class are returned
+     * @template T of Warning
+     * @param class-string<T>|null $messageTypeFilter if specified only warnings implementing the given class are returned
      * @return array<Warning>
      * @api
      */
     public function getWarnings(?string $messageTypeFilter = null): array
     {
-        return $this->filterMessages($this->warnings, $messageTypeFilter);
+        return $this->filterMessages($this->warnings, $messageTypeFilter ?: Warning::class);
     }
 
     /**
      * Get all notices in the current Result object (non-recursive)
      *
-     * @param string $messageTypeFilter if specified only notices implementing the given class are returned
+     * @template T of Notice
+     * @param class-string<T>|null $messageTypeFilter if specified only notices implementing the given class are returned
      * @return array<Notice>
      * @api
      */
     public function getNotices(?string $messageTypeFilter = null): array
     {
-        return $this->filterMessages($this->notices, $messageTypeFilter);
+        return $this->filterMessages($this->notices, $messageTypeFilter ?: Notice::class);
     }
 
     /**
      * Get the first error object of the current Result object (non-recursive)
      *
-     * @param string $messageTypeFilter if specified only errors implementing the given class are considered
-     * @return Error
+     * @template T of Error
+     * @param class-string<T>|null $messageTypeFilter if specified only errors implementing the given class are considered
+     * @return ($messageTypeFilter is null ? ?Error : ?T)
      * @api
      */
     public function getFirstError(?string $messageTypeFilter = null)
     {
         $matchingErrors = $this->filterMessages($this->errors, $messageTypeFilter);
-        reset($matchingErrors);
-        return current($matchingErrors);
+        $result = reset($matchingErrors);
+
+        return $result instanceof Error ? $result : null;
     }
 
     /**
      * Get the first warning object of the current Result object (non-recursive)
      *
-     * @param string $messageTypeFilter if specified only warnings implementing the given class are considered
-     * @return Warning
+     * @template T of Warning
+     * @param ?class-string<T> $messageTypeFilter if specified only warnings implementing the given class are considered
+     * @return ($messageTypeFilter is null ? ?Warning : ?T)
      * @api
      */
     public function getFirstWarning(?string $messageTypeFilter = null)
     {
-        $matchingWarnings = $this->filterMessages($this->warnings, $messageTypeFilter);
+        $matchingWarnings = $this->filterMessages($this->warnings, $messageTypeFilter ?: Warning::class);
         reset($matchingWarnings);
-        return current($matchingWarnings);
+        return current($matchingWarnings) ?: null;
     }
 
     /**
      * Get the first notice object of the current Result object (non-recursive)
      *
-     * @param string $messageTypeFilter if specified only notices implementing the given class are considered
-     * @return Notice
+     * @template T of Notice
+     * @param ?class-string<T> $messageTypeFilter if specified only notices implementing the given class are considered
+     * @return ($messageTypeFilter is null ? ?Notice : ?T)
      * @api
      */
     public function getFirstNotice(?string $messageTypeFilter = null)
     {
-        $matchingNotices = $this->filterMessages($this->notices, $messageTypeFilter);
+        $matchingNotices = $this->filterMessages($this->notices, $messageTypeFilter ?: Notice::class);
         reset($matchingNotices);
-        return current($matchingNotices);
+        return current($matchingNotices) ?: null;
     }
 
     /**
@@ -232,7 +239,7 @@ public function forProperty(?string $propertyPath = null): Result
     /**
      * Internal use only!
      *
-     * @param array $pathSegments
+     * @param array<string> $pathSegments
      * @return Result
      */
     public function recurseThroughResult(array $pathSegments): Result
@@ -249,7 +256,6 @@ public function recurseThroughResult(array $pathSegments): Result
             $this->propertyResults[$propertyName] = $newResult;
         }
 
-        /** @var Result $result */
         $result = $this->propertyResults[$propertyName];
         return $result->recurseThroughResult($pathSegments);
     }
@@ -360,8 +366,9 @@ public function getFlattenedErrors(): array
      * where the key is the property path where the error occurred, and the
      * value is a list of all errors (stored as array)
      *
-     * @param string $type
-     * @return array<string, array<int, Error>>
+     * @template T of Error
+     * @param class-string<T> $type
+     * @return array<string, array<int, T>>
      * @api
      */
     public function getFlattenedErrorsOfType(string $type): array
@@ -404,11 +411,11 @@ public function getFlattenedNotices(): array
     /**
      * Flatten a tree of Result objects, based on a certain property.
      *
+     * @template T of Message
      * @param string $propertyName
-     * @param array $result The current result to be flattened
-     * @param array $level The property path in the format array('level1', 'level2', ...) for recursion
-     * @param string $messageTypeFilter If specified only messages implementing the given class name are taken into account
-     * @param-out array<string, array<int, mixed>> $result
+     * @param array<mixed> $result The current result to be flattened
+     * @param array<string> $level The property path in the format array('level1', 'level2', ...) for recursion
+     * @param ?class-string<T> $messageTypeFilter $messageTypeFilter If specified only messages implementing the given class name are taken into account
      * @return void
      */
     public function flattenTree(string $propertyName, array &$result, array $level = [], ?string $messageTypeFilter = null)
@@ -417,7 +424,6 @@ public function flattenTree(string $propertyName, array &$result, array $level =
             $propertyPath = implode('.', $level);
             $result[$propertyPath] = $this->filterMessages($this->$propertyName, $messageTypeFilter);
         }
-        /** @var Result $subResult */
         foreach ($this->propertyResults as $subPropertyName => $subResult) {
             array_push($level, $subPropertyName);
             $subResult->flattenTree($propertyName, $result, $level, $messageTypeFilter);
@@ -426,9 +432,10 @@ public function flattenTree(string $propertyName, array &$result, array $level =
     }
 
     /**
-     * @param Message[] $messages an array of Message instances to filter
-     * @param string $messageTypeFilter If specified only messages implementing the given class name are taken into account
-     * @return array the filtered message instances
+     * @template T of Message
+     * @param array<Message> $messages an array of Message instances to filter
+     * @param ?class-string<T> $messageTypeFilter If specified only messages implementing the given class name are taken into account
+     * @return ($messageTypeFilter is null ? array<Message> : array<T>) array the filtered message instances
      */
     protected function filterMessages(array $messages, ?string $messageTypeFilter = null): array
     {
diff --git a/Neos.Flow.Log/Classes/Backend/AbstractBackend.php b/Neos.Flow.Log/Classes/Backend/AbstractBackend.php
index 6279d6cd85..1e879d90db 100644
--- a/Neos.Flow.Log/Classes/Backend/AbstractBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/AbstractBackend.php
@@ -42,7 +42,7 @@ abstract class AbstractBackend implements BackendInterface
      */
     public function __construct($options = [])
     {
-        if (is_array($options) || $options instanceof \ArrayAccess) {
+        if (is_iterable($options)) {
             foreach ($options as $optionKey => $optionValue) {
                 $methodName = 'set' . ucfirst($optionKey);
                 if (method_exists($this, $methodName)) {
diff --git a/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php b/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php
index 5749b5df81..30784f9aef 100644
--- a/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/AnsiConsoleBackend.php
@@ -40,7 +40,7 @@ class AnsiConsoleBackend extends ConsoleBackend
     const END = "\033[0m";
 
     /**
-     * @var array
+     * @var array<string,string>
      */
     protected $tagFormats = [];
 
@@ -75,12 +75,7 @@ public function open(): void
     /**
      * Appends the given message along with the additional information into the log.
      *
-     * @param string $message
-     * @param int $severity
-     * @param array $additionalData
-     * @param string $packageKey
-     * @param string $className
-     * @param string $methodName
+     * @param array<mixed>|null $additionalData
      * @return void
      */
     public function append(string $message, int $severity = LOG_INFO, $additionalData = null, ?string $packageKey = null, ?string $className = null, ?string $methodName = null): void
@@ -118,7 +113,7 @@ protected function formatOutput($output)
                 } else {
                     return str_replace('|', $matches[3], $format);
                 }
-            }, $output);
+            }, $output) ?: '';
         } while ($lastOutput !== $output);
         return $output;
     }
@@ -126,7 +121,7 @@ protected function formatOutput($output)
     /**
      * @param boolean $disableAnsi
      */
-    public function setDisableAnsi($disableAnsi)
+    public function setDisableAnsi($disableAnsi): void
     {
         $this->disableAnsi = $disableAnsi;
     }
diff --git a/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php b/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php
index def5dd734e..1398b288c9 100644
--- a/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/ConsoleBackend.php
@@ -25,7 +25,7 @@ class ConsoleBackend extends AbstractBackend
 {
     /**
      * An array of severity labels, indexed by their integer constant
-     * @var array
+     * @var array<int,string>
      */
     protected $severityLabels;
 
@@ -61,10 +61,11 @@ public function open(): void
             LOG_DEBUG => 'DEBUG    ',
         ];
 
-        $this->streamHandle = fopen('php://' . $this->streamName, 'w');
-        if (!is_resource($this->streamHandle)) {
+        $streamHandle = fopen('php://' . $this->streamName, 'w');
+        if (!is_resource($streamHandle)) {
             throw new CouldNotOpenResourceException('Could not open stream "' . $this->streamName . '" for write access.', 1310986609);
         }
+        $this->streamHandle = $streamHandle;
     }
 
     /**
diff --git a/Neos.Flow.Log/Classes/Backend/FileBackend.php b/Neos.Flow.Log/Classes/Backend/FileBackend.php
index 67a3ac2aaf..7a19df4a97 100644
--- a/Neos.Flow.Log/Classes/Backend/FileBackend.php
+++ b/Neos.Flow.Log/Classes/Backend/FileBackend.php
@@ -27,7 +27,7 @@ class FileBackend extends AbstractBackend
 {
     /**
      * An array of severity labels, indexed by their integer constant
-     * @var array
+     * @var array<int,string>
      */
     protected $severityLabels;
 
diff --git a/Neos.Flow.Log/Classes/PlainTextFormatter.php b/Neos.Flow.Log/Classes/PlainTextFormatter.php
index 0a15efb126..5590dbbed2 100644
--- a/Neos.Flow.Log/Classes/PlainTextFormatter.php
+++ b/Neos.Flow.Log/Classes/PlainTextFormatter.php
@@ -22,10 +22,9 @@ public function __construct($variable)
     }
 
     /**
-     * @param $spaces
-     * @return string
+     * @return ?string
      */
-    public function format($spaces = 4)
+    public function format(int $spaces = 4)
     {
         return $this->renderVariableAsPlaintext($this->variable, $spaces);
     }
diff --git a/Neos.Flow.Log/Classes/Psr/Logger.php b/Neos.Flow.Log/Classes/Psr/Logger.php
index 6ebad73f56..c1a18be6f8 100644
--- a/Neos.Flow.Log/Classes/Psr/Logger.php
+++ b/Neos.Flow.Log/Classes/Psr/Logger.php
@@ -45,7 +45,7 @@ class Logger implements LoggerInterface
     /**
      * Constructs the PSR-3 Logger.
      *
-     * @param iterable $backends
+     * @param iterable<mixed> $backends
      */
     public function __construct(iterable $backends)
     {
@@ -61,7 +61,7 @@ public function __construct(iterable $backends)
     /**
      * @param mixed $level
      * @param string|\Stringable $message
-     * @param array $context
+     * @param array<string,mixed> $context
      * @api
      */
     public function log($level, string|\Stringable $message, array $context = []): void
@@ -80,8 +80,8 @@ public function log($level, string|\Stringable $message, array $context = []): v
     }
 
     /**
-     * @param array $context
-     * @return array list of packageKey, className and methodName either string or null
+     * @param array<string,mixed> $context
+     * @return array<int,string|null> list of packageKey, className and methodName either string or null
      */
     protected function extractLegacyDataFromContext(array $context): array
     {
@@ -93,8 +93,8 @@ protected function extractLegacyDataFromContext(array $context): array
     }
 
     /**
-     * @param array $context
-     * @return array
+     * @param array<string,mixed> $context
+     * @return array<string,mixed>
      */
     protected function removeLegacyDataFromContext(array $context): array
     {
diff --git a/Neos.Flow/Classes/Annotations/Introduce.php b/Neos.Flow/Classes/Annotations/Introduce.php
index 2378ffecf0..2a514cf9c3 100644
--- a/Neos.Flow/Classes/Annotations/Introduce.php
+++ b/Neos.Flow/Classes/Annotations/Introduce.php
@@ -33,17 +33,21 @@ final class Introduce
 
     /**
      * The interface name to introduce.
-     * @var string|null
+     * @var class-string|null
      */
     public $interfaceName;
 
     /**
      * The trait name to introduce
      *
-     * @var string|null
+     * @var trait-string|null
      */
     public $traitName;
 
+    /**
+     * @param class-string|null $interfaceName
+     * @param trait-string|null $traitName
+     */
     public function __construct(string $pointcutExpression, ?string $interfaceName = null, ?string $traitName = null)
     {
         $this->pointcutExpression = $pointcutExpression;
diff --git a/Neos.Flow/Classes/Annotations/Route.php b/Neos.Flow/Classes/Annotations/Route.php
index 4d9e8d86d3..cf2ca2c2a7 100644
--- a/Neos.Flow/Classes/Annotations/Route.php
+++ b/Neos.Flow/Classes/Annotations/Route.php
@@ -38,8 +38,8 @@
     /**
      * @param string $uriPattern The uri-pattern for the route without leading '/'. Might contain route values in the form of `path/{foo}`
      * @param string $name The suffix of the route name as shown in `route:list` (defaults to the action name: "My.Package :: Site :: index")
-     * @param array $httpMethods List of uppercase http verbs like 'GET', 'POST', 'PUT', 'DELETE', if not specified any request method will be matched
-     * @param array $defaults Values to set for this route
+     * @param list<string> $httpMethods List of uppercase http verbs like 'GET', 'POST', 'PUT', 'DELETE', if not specified any request method will be matched
+     * @param array<string,mixed> $defaults Values to set for this route
      */
     public function __construct(
         public string $uriPattern,
diff --git a/Neos.Flow/Classes/Annotations/Validate.php b/Neos.Flow/Classes/Annotations/Validate.php
index eccf3927db..db627d01e0 100644
--- a/Neos.Flow/Classes/Annotations/Validate.php
+++ b/Neos.Flow/Classes/Annotations/Validate.php
@@ -31,7 +31,7 @@ final class Validate
 
     /**
      * Options for the validator, validator-specific.
-     * @var array
+     * @var array<mixed>
      */
     public $options = [];
 
@@ -43,10 +43,14 @@ final class Validate
 
     /**
      * The validation groups for which this validator should be executed.
-     * @var array
+     * @var array<int,string>
      */
     public $validationGroups = ['Default'];
 
+    /**
+     * @param array<mixed> $options
+     * @param array<int,string>|null $validationGroups
+     */
     public function __construct(?string $argumentName = null, ?string $type = null, array $options = [], ?array $validationGroups = null)
     {
         $this->type = $type;
diff --git a/Neos.Flow/Classes/Annotations/ValidationGroups.php b/Neos.Flow/Classes/Annotations/ValidationGroups.php
index fcac75c8b6..838efbc0d2 100644
--- a/Neos.Flow/Classes/Annotations/ValidationGroups.php
+++ b/Neos.Flow/Classes/Annotations/ValidationGroups.php
@@ -24,10 +24,13 @@ final class ValidationGroups
 {
     /**
      * The validation groups for which validation on this method should be executed. (Can be given as anonymous argument.)
-     * @var array
+     * @var array<int,string>
      */
     public $validationGroups = ['Default', 'Controller'];
 
+    /**
+     * @param array<int,string> $validationGroups
+     */
     public function __construct(array $validationGroups)
     {
         $this->validationGroups = $validationGroups;
diff --git a/Neos.Flow/Classes/Aop/Advice/AbstractAdvice.php b/Neos.Flow/Classes/Aop/Advice/AbstractAdvice.php
index e77c1eddc8..a1fa1640c8 100644
--- a/Neos.Flow/Classes/Aop/Advice/AbstractAdvice.php
+++ b/Neos.Flow/Classes/Aop/Advice/AbstractAdvice.php
@@ -24,7 +24,7 @@ class AbstractAdvice implements AdviceInterface
 {
     /**
      * Holds the name of the aspect object containing the advice
-     * @var string
+     * @var class-string
      */
     protected $aspectObjectName;
 
@@ -42,29 +42,29 @@ class AbstractAdvice implements AdviceInterface
 
     /**
      * A reference to the Object Manager
-     * @var ObjectManagerInterface
+     * @var ?ObjectManagerInterface
      */
     protected $objectManager;
 
     /**
      * Runtime evaluations definition array
-     * @var array
+     * @var array<mixed>
      */
     protected $runtimeEvaluationsDefinition;
 
     /**
      * Runtime evaluations function
-     * @var \Closure
+     * @var ?\Closure
      */
     protected $runtimeEvaluator;
 
     /**
      * Constructor
      *
-     * @param string $aspectObjectName Name of the aspect object containing the advice
+     * @param class-string $aspectObjectName Name of the aspect object containing the advice
      * @param string $adviceMethodName Name of the advice method
-     * @param ObjectManagerInterface $objectManager Only require if a runtime evaluations function is specified
-     * @param \Closure $runtimeEvaluator Runtime evaluations function
+     * @param ?ObjectManagerInterface $objectManager Only require if a runtime evaluations function is specified
+     * @param ?\Closure $runtimeEvaluator Runtime evaluations function
      */
     public function __construct(string $aspectObjectName, string $adviceMethodName, ?ObjectManagerInterface $objectManager = null, ?\Closure $runtimeEvaluator = null)
     {
@@ -86,6 +86,9 @@ public function invoke(JoinPointInterface $joinPoint)
             return;
         }
 
+        if ($this->objectManager === null) {
+            throw new \RuntimeException('Object manager is missing', 1744496555);
+        }
         $adviceObject = $this->objectManager->get($this->aspectObjectName);
         $methodName = $this->adviceMethodName;
         $adviceObject->$methodName($joinPoint);
@@ -96,7 +99,7 @@ public function invoke(JoinPointInterface $joinPoint)
     /**
      * Returns the aspect's object name which has been passed to the constructor
      *
-     * @return string The object name of the aspect
+     * @return class-string The object name of the aspect
      */
     public function getAspectObjectName(): string
     {
@@ -127,6 +130,9 @@ public function getAdviceMethodName(): string
     protected function emitAdviceInvoked($aspectObject, string $methodName, JoinPointInterface $joinPoint): void
     {
         if ($this->dispatcher === null) {
+            if ($this->objectManager === null) {
+                throw new \RuntimeException('Object manager is missing', 1744496534);
+            }
             $this->dispatcher = $this->objectManager->get(Dispatcher::class);
         }
 
diff --git a/Neos.Flow/Classes/Aop/Advice/AdviceChain.php b/Neos.Flow/Classes/Aop/Advice/AdviceChain.php
index 21da910d4b..7349fb8eee 100644
--- a/Neos.Flow/Classes/Aop/Advice/AdviceChain.php
+++ b/Neos.Flow/Classes/Aop/Advice/AdviceChain.php
@@ -22,7 +22,7 @@ class AdviceChain
 {
     /**
      * An array of Advice objects which form the advice chain
-     * @var array
+     * @var array<AdviceInterface>
      */
     protected $advices;
 
@@ -35,7 +35,7 @@ class AdviceChain
     /**
      * Initializes the advice chain
      *
-     * @param array $advices An array of AdviceInterface compatible objects which form the chain of advices
+     * @param array<AdviceInterface> $advices An array of AdviceInterface compatible objects which form the chain of advices
      */
     public function __construct(array $advices)
     {
@@ -48,7 +48,7 @@ public function __construct(array $advices)
      * left in the chain, the proxy classes' method invokeJoinpoint() will finally
      * be called.
      *
-     * @param  JoinPointInterface $joinPoint The current join point (ie. the context)
+     * @param JoinPointInterface $joinPoint The current join point (ie. the context)
      * @return mixed Result of the advice or the original method of the target class
      */
     public function proceed(JoinPointInterface &$joinPoint)
diff --git a/Neos.Flow/Classes/Aop/Advice/AroundAdvice.php b/Neos.Flow/Classes/Aop/Advice/AroundAdvice.php
index 8f58cbceac..ed5ad56833 100644
--- a/Neos.Flow/Classes/Aop/Advice/AroundAdvice.php
+++ b/Neos.Flow/Classes/Aop/Advice/AroundAdvice.php
@@ -30,6 +30,9 @@ public function invoke(JoinPointInterface $joinPoint)
             return $joinPoint->getAdviceChain()->proceed($joinPoint);
         }
 
+        if ($this->objectManager === null) {
+            throw new \RuntimeException('Object manager is missing', 1744496510);
+        }
         $adviceObject = $this->objectManager->get($this->aspectObjectName);
         $methodName = $this->adviceMethodName;
         $result = $adviceObject->$methodName($joinPoint);
diff --git a/Neos.Flow/Classes/Aop/AdvicesTrait.php b/Neos.Flow/Classes/Aop/AdvicesTrait.php
index 9cd4793be9..e28cf39816 100644
--- a/Neos.Flow/Classes/Aop/AdvicesTrait.php
+++ b/Neos.Flow/Classes/Aop/AdvicesTrait.php
@@ -14,6 +14,7 @@
 /**
  * Contains boilerplate code for AOP execution and is added to AOP proxy classes.
  *
+ * @phpstan-ignore trait.unused (probably API)
  */
 trait AdvicesTrait
 {
diff --git a/Neos.Flow/Classes/Aop/AspectContainer.php b/Neos.Flow/Classes/Aop/AspectContainer.php
index c66d8a6b58..89cab12f0b 100644
--- a/Neos.Flow/Classes/Aop/AspectContainer.php
+++ b/Neos.Flow/Classes/Aop/AspectContainer.php
@@ -38,37 +38,32 @@
 class AspectContainer
 {
     /**
-     * @var string
+     * @var class-string
      */
     protected $className;
 
     /**
-     * An array of \Neos\Flow\Aop\Advisor objects
-     * @var array
+     * @var array<Advisor>
      */
     protected $advisors = [];
 
     /**
-     * An array of \Neos\Flow\Aop\InterfaceIntroduction objects
-     * @var array
+     * @var array<InterfaceIntroduction>
      */
     protected $interfaceIntroductions = [];
 
     /**
-     * An array of \Neos\Flow\Aop\PropertyIntroduction objects
-     * @var array
+     * @var array<PropertyIntroduction>
      */
     protected $propertyIntroductions = [];
 
     /**
-     * An array of \Neos\Flow\Aop\TraitIntroduction objects
-     * @var array
+     * @var array<TraitIntroduction>
      */
     protected $traitIntroductions = [];
 
     /**
-     * An array of explicitly declared \Neos\Flow\Pointcut objects
-     * @var array
+     * @var array<Pointcut>
      */
     protected $pointcuts = [];
 
@@ -80,7 +75,7 @@ class AspectContainer
     /**
      * The constructor
      *
-     * @param string $className Name of the aspect class
+     * @param class-string $className Name of the aspect class
      */
     public function __construct(string $className)
     {
@@ -90,7 +85,7 @@ public function __construct(string $className)
     /**
      * Returns the name of the aspect class
      *
-     * @return string Name of the aspect class
+     * @return class-string Name of the aspect class
      */
     public function getClassName(): string
     {
@@ -100,7 +95,7 @@ public function getClassName(): string
     /**
      * Returns the advisors which were defined in the aspect
      *
-     * @return array Array of \Neos\Flow\Aop\Advisor objects
+     * @return array<Advisor>
      */
     public function getAdvisors(): array
     {
@@ -110,7 +105,7 @@ public function getAdvisors(): array
     /**
      * Returns the interface introductions which were defined in the aspect
      *
-     * @return array Array of \Neos\Flow\Aop\InterfaceIntroduction objects
+     * @return array<InterfaceIntroduction>
      */
     public function getInterfaceIntroductions(): array
     {
@@ -120,7 +115,7 @@ public function getInterfaceIntroductions(): array
     /**
      * Returns the property introductions which were defined in the aspect
      *
-     * @return array Array of \Neos\Flow\Aop\PropertyIntroduction objects
+     * @return array<PropertyIntroduction>
      */
     public function getPropertyIntroductions(): array
     {
@@ -130,7 +125,7 @@ public function getPropertyIntroductions(): array
     /**
      * Returns the trait introductions which were defined in the aspect
      *
-     * @return array Array of \Neos\Flow\Aop\TraitIntroduction objects
+     * @return array<TraitIntroduction> Array of \Neos\Flow\Aop\TraitIntroduction objects
      */
     public function getTraitIntroductions(): array
     {
@@ -142,7 +137,7 @@ public function getTraitIntroductions(): array
      * does not contain the pointcuts which were made out of the pointcut
      * expressions for the advisors!
      *
-     * @return array Array of \Neos\Flow\Aop\Pointcut\Pointcut objects
+     * @return array<Pointcut>
      */
     public function getPointcuts(): array
     {
diff --git a/Neos.Flow/Classes/Aop/Builder/AbstractMethodInterceptorBuilder.php b/Neos.Flow/Classes/Aop/Builder/AbstractMethodInterceptorBuilder.php
index b3b4d987e3..59d02dcd04 100644
--- a/Neos.Flow/Classes/Aop/Builder/AbstractMethodInterceptorBuilder.php
+++ b/Neos.Flow/Classes/Aop/Builder/AbstractMethodInterceptorBuilder.php
@@ -54,8 +54,8 @@ public function injectCompiler(Compiler $compiler): void
      * Builds method interception PHP code
      *
      * @param string $methodName Name of the method to build an interceptor for
-     * @param array $methodMetaInformation An array of method names and their meta information, including advices for the method (if any)
-     * @param string $targetClassName Name of the target class to build the interceptor for
+     * @param array<mixed> $methodMetaInformation An array of method names and their meta information, including advices for the method (if any)
+     * @param class-string $targetClassName Name of the target class to build the interceptor for
      * @return void
      */
     abstract public function build(string $methodName, array $methodMetaInformation, string $targetClassName): void;
@@ -63,7 +63,7 @@ abstract public function build(string $methodName, array $methodMetaInformation,
     /**
      * Builds a string containing PHP code to build the array given as input.
      *
-     * @param array $array
+     * @param array<mixed> $array
      * @return string e.g. 'array()' or 'array(1 => 'bar')
      */
     protected function buildArraySetupCode(array $array): string
@@ -91,7 +91,7 @@ protected function buildArraySetupCode(array $array): string
      * the constructor of a new join point. Used in the method interceptor
      * functions.
      *
-     * @param string|null $className Name of the declaring class of the method
+     * @param class-string|null $className Name of the declaring class of the method
      * @param string|null $methodName Name of the method to create arguments array code for
      * @param bool $useArgumentsArray If set, the $methodArguments array will be built from $arguments instead of using the actual parameter variables.
      * @return string The generated code to be used in an "array()" definition
@@ -126,8 +126,9 @@ protected function buildMethodArgumentsArrayCode(?string $className = null, ?str
     /**
      * Generates the parameters code needed to call the constructor with the saved parameters.
      *
-     * @param string|null $className Name of the class the method is declared in
+     * @param class-string|null $className Name of the class the method is declared in
      * @return string The generated parameters code
+     * @todo can this be removed?
      */
     protected function buildSavedConstructorParametersCode(?string $className = null): string
     {
@@ -150,10 +151,10 @@ protected function buildSavedConstructorParametersCode(?string $className = null
     /**
      * Builds the advice interception code, to be used in a method interceptor.
      *
-     * @param array $groupedAdvices The advices grouped by advice type
+     * @param array<string,mixed> $groupedAdvices The advices grouped by advice type
      * @param string|null $methodName Name of the method the advice applies to
-     * @param string|null $targetClassName Name of the target class
-     * @param string|null $declaringClassName Name of the declaring class. This is usually the same as the $targetClassName. However, it is the introduction interface for introduced methods.
+     * @param class-string|null $targetClassName Name of the target class
+     * @param class-string|null $declaringClassName Name of the declaring class. This is usually the same as the $targetClassName. However, it is the introduction interface for introduced methods.
      * @return string PHP code to be used in the method interceptor
      */
     protected function buildAdvicesCode(array $groupedAdvices, ?string $methodName = null, ?string $targetClassName = null, ?string $declaringClassName = null): string
diff --git a/Neos.Flow/Classes/Aop/Builder/AdvisedConstructorInterceptorBuilder.php b/Neos.Flow/Classes/Aop/Builder/AdvisedConstructorInterceptorBuilder.php
index baaa0c188e..219e9cc4ad 100644
--- a/Neos.Flow/Classes/Aop/Builder/AdvisedConstructorInterceptorBuilder.php
+++ b/Neos.Flow/Classes/Aop/Builder/AdvisedConstructorInterceptorBuilder.php
@@ -26,8 +26,8 @@ class AdvisedConstructorInterceptorBuilder extends AbstractMethodInterceptorBuil
      * Builds interception PHP code for an advised constructor
      *
      * @param string $methodName Name of the method to build an interceptor for
-     * @param array $methodMetaInformation An array of method names and their meta information, including advices for the method (if any)
-     * @param string $targetClassName Name of the target class to build the interceptor for
+     * @param array<string,mixed> $methodMetaInformation An array of method names and their meta information, including advices for the method (if any)
+     * @param class-string $targetClassName Name of the target class to build the interceptor for
      * @return void
      * @throws Exception
      */
@@ -38,7 +38,11 @@ public function build(string $methodName, array $methodMetaInformation, string $
         }
 
         $declaringClassName = $methodMetaInformation[$methodName]['declaringClassName'];
-        $proxyMethod = $this->compiler->getProxyClass($targetClassName)->getConstructor();
+        $proxyClass = $this->compiler->getProxyClass($targetClassName);
+        if ($proxyClass === false) {
+            throw new \InvalidArgumentException('Cannot build proxy class for '. $targetClassName, 1744495809);
+        }
+        $proxyMethod = $proxyClass->getConstructor();
 
         $groupedAdvices = $methodMetaInformation[$methodName]['groupedAdvices'];
         $advicesCode = $this->buildAdvicesCode($groupedAdvices, $methodName, $targetClassName, $declaringClassName);
diff --git a/Neos.Flow/Classes/Aop/Builder/AdvisedMethodInterceptorBuilder.php b/Neos.Flow/Classes/Aop/Builder/AdvisedMethodInterceptorBuilder.php
index e0f7107500..b2e49160a7 100644
--- a/Neos.Flow/Classes/Aop/Builder/AdvisedMethodInterceptorBuilder.php
+++ b/Neos.Flow/Classes/Aop/Builder/AdvisedMethodInterceptorBuilder.php
@@ -27,8 +27,8 @@ class AdvisedMethodInterceptorBuilder extends AbstractMethodInterceptorBuilder
      * Builds interception PHP code for an advised method
      *
      * @param string $methodName Name of the method to build an interceptor for
-     * @param array $methodMetaInformation An array of method names and their meta information, including advices for the method (if any)
-     * @param string $targetClassName Name of the target class to build the interceptor for
+     * @param array<string,mixed> $methodMetaInformation An array of method names and their meta information, including advices for the method (if any)
+     * @param class-string $targetClassName Name of the target class to build the interceptor for
      * @return void
      * @throws Exception
      */
@@ -39,7 +39,11 @@ public function build(string $methodName, array $methodMetaInformation, string $
         }
 
         $declaringClassName = $methodMetaInformation[$methodName]['declaringClassName'];
-        $proxyMethod = $this->compiler->getProxyClass($targetClassName)->getMethod($methodName);
+        $proxyClass = $this->compiler->getProxyClass($targetClassName);
+        if ($proxyClass === false) {
+            throw new \InvalidArgumentException('Cannot build proxy class for ' . $targetClassName);
+        }
+        $proxyMethod = $proxyClass->getMethod($methodName);
         if ($proxyMethod->getVisibility() === ProxyMethodGenerator::VISIBILITY_PRIVATE) {
             throw new Exception(sprintf('The %s cannot build interceptor code for private method %s::%s(). Please change the scope to at least protected or adjust the pointcut expression in the corresponding aspect.', __CLASS__, $targetClassName, $methodName), 1593070574);
         }
diff --git a/Neos.Flow/Classes/Aop/Builder/ClassNameIndex.php b/Neos.Flow/Classes/Aop/Builder/ClassNameIndex.php
index a8a4a7046a..e7c71924f2 100644
--- a/Neos.Flow/Classes/Aop/Builder/ClassNameIndex.php
+++ b/Neos.Flow/Classes/Aop/Builder/ClassNameIndex.php
@@ -23,7 +23,7 @@ class ClassNameIndex
 {
     /**
      * Indexed array by class name
-     * @var array
+     * @var array<class-string,true>
      */
     protected $classNames = [];
 
@@ -31,7 +31,7 @@ class ClassNameIndex
      * Constructor. Note: If you pass a data array here, make sure
      * to key sort it before!
      *
-     * @param array $classNames Array with class names as keys
+     * @param array<class-string,true> $classNames Array with class names as keys
      */
     public function __construct(array $classNames = [])
     {
@@ -42,7 +42,7 @@ public function __construct(array $classNames = [])
      * Set the data of this index to the given class
      * names. Note: Make sure to sort the array before!
      *
-     * @param array $classNames
+     * @param array<class-string> $classNames
      * @return void
      */
     public function setClassNames(array $classNames): void
@@ -53,7 +53,7 @@ public function setClassNames(array $classNames): void
     /**
      * Returns the class names contained in this index
      *
-     * @return array An array of class names contained in this index
+     * @return array<class-string> An array of class names contained in this index
      */
     public function getClassNames(): array
     {
@@ -63,7 +63,7 @@ public function getClassNames(): array
     /**
      * Checks, if a class name is contained in this index
      *
-     * @param string $className The class name to check for
+     * @param class-string $className The class name to check for
      * @return bool true, if the given class name is contained in this index
      */
     public function hasClassName(string $className): bool
diff --git a/Neos.Flow/Classes/Aop/Builder/ProxyClassBuilder.php b/Neos.Flow/Classes/Aop/Builder/ProxyClassBuilder.php
index a175e0cf8d..72dc52499f 100644
--- a/Neos.Flow/Classes/Aop/Builder/ProxyClassBuilder.php
+++ b/Neos.Flow/Classes/Aop/Builder/ProxyClassBuilder.php
@@ -49,18 +49,29 @@ class ProxyClassBuilder
     protected LoggerInterface $logger;
     protected PointcutExpressionParser $pointcutExpressionParser;
     protected VariableFrontend $objectConfigurationCache;
+    /** @var CompileTimeObjectManager<object> */
     protected CompileTimeObjectManager $objectManager;
 
     /**
      * Hardcoded list of Flow sub packages (first 15 characters) which must be immune to AOP proxying for security, technical or conceptual reasons.
+     *
+     * @var array<int,string>
      */
     protected array $excludedSubPackages = ['Neos\Flow\Aop\\', 'Neos\Flow\Cach', 'Neos\Flow\Erro', 'Neos\Flow\Log\\', 'Neos\Flow\Moni', 'Neos\Flow\Obje', 'Neos\Flow\Pack', 'Neos\Flow\Prop', 'Neos\Flow\Refl', 'Neos\Flow\Util', 'Neos\Flow\Vali'];
 
     /**
      * A registry of all known aspects
+     *
+     * @var array<class-string,AspectContainer>
      */
     protected array $aspectContainers = [];
 
+    /**
+     * @var array{
+     *     AdvisedConstructor?: AdvisedConstructorInterceptorBuilder,
+     *     AdvisedMethod?: AdvisedMethodInterceptorBuilder,
+     * }
+     */
     protected array $methodInterceptorBuilders = [];
 
     public function injectCompiler(Compiler $compiler): void
@@ -100,6 +111,9 @@ public function injectAdvisedMethodInterceptorBuilder(AdvisedMethodInterceptorBu
         $this->methodInterceptorBuilders['AdvisedMethod'] = $builder;
     }
 
+    /**
+     * @param CompileTimeObjectManager<object> $objectManager
+     */
     public function injectObjectManager(CompileTimeObjectManager $objectManager): void
     {
         $this->objectManager = $objectManager;
@@ -207,8 +221,8 @@ public function findPointcut(string $aspectClassName, string $pointcutMethodName
      * Determines which of the given classes are potentially proxyable
      * and returns their names in an array.
      *
-     * @param array $classNamesByPackage Names of the classes to check
-     * @return array Names of classes which can be proxied
+     * @param array<string,array<class-string>> $classNamesByPackage Names of the classes to check
+     * @return array<int,class-string> Names of classes which can be proxied
      */
     protected function getProxyableClasses(array $classNamesByPackage): array
     {
@@ -232,8 +246,9 @@ protected function getProxyableClasses(array $classNamesByPackage): array
      * Checks the annotations of the specified classes for aspect tags
      * and creates an aspect with advisors accordingly.
      *
-     * @param array $classNames Classes to check for aspect tags.
-     * @return array An array of Aop\AspectContainer for all aspects which were found.
+     * @template T of object
+     * @param array<class-string<T>> $classNames Classes to check for aspect tags.
+     * @return array<class-string<T>,AspectContainer> An array of Aop\AspectContainer for all aspects which were found.
      * @throws Exception
      * @throws FilesException
      * @throws InvalidPointcutExpressionException
@@ -254,7 +269,7 @@ protected function buildAspectContainers(array $classNames): array
      * is tagged as an aspect. The object acting as an advice will already be
      * fetched (and therefore instantiated if necessary).
      *
-     * @param string $aspectClassName Name of the class which forms the aspect, contains advices etc.
+     * @param class-string $aspectClassName Name of the class which forms the aspect, contains advices etc.
      * @return AspectContainer The aspect container containing one or more advisors
      * @throws Exception
      * @throws InvalidPointcutExpressionException
@@ -275,6 +290,7 @@ protected function buildAspectContainer(string $aspectClassName): AspectContaine
                 $annotationClass = get_class($annotation);
                 switch ($annotationClass) {
                     case Flow\Around::class:
+                        /** @var Flow\Around $annotation */
                         $pointcutFilterComposite = $this->pointcutExpressionParser->parse($annotation->pointcutExpression, $this->renderSourceHint($aspectClassName, $methodName, $annotationClass));
                         $advice = new Aop\Advice\AroundAdvice($aspectClassName, $methodName);
                         $pointcut = new Pointcut($annotation->pointcutExpression, $pointcutFilterComposite, $aspectClassName);
@@ -282,6 +298,7 @@ protected function buildAspectContainer(string $aspectClassName): AspectContaine
                         $aspectContainer->addAdvisor($advisor);
                         break;
                     case Flow\Before::class:
+                        /** @var Flow\Before $annotation */
                         $pointcutFilterComposite = $this->pointcutExpressionParser->parse($annotation->pointcutExpression, $this->renderSourceHint($aspectClassName, $methodName, $annotationClass));
                         $advice = new Aop\Advice\BeforeAdvice($aspectClassName, $methodName);
                         $pointcut = new Pointcut($annotation->pointcutExpression, $pointcutFilterComposite, $aspectClassName);
@@ -289,6 +306,7 @@ protected function buildAspectContainer(string $aspectClassName): AspectContaine
                         $aspectContainer->addAdvisor($advisor);
                         break;
                     case Flow\AfterReturning::class:
+                        /** @var Flow\AfterReturning $annotation */
                         $pointcutFilterComposite = $this->pointcutExpressionParser->parse($annotation->pointcutExpression, $this->renderSourceHint($aspectClassName, $methodName, $annotationClass));
                         $advice = new Aop\Advice\AfterReturningAdvice($aspectClassName, $methodName);
                         $pointcut = new Pointcut($annotation->pointcutExpression, $pointcutFilterComposite, $aspectClassName);
@@ -296,6 +314,7 @@ protected function buildAspectContainer(string $aspectClassName): AspectContaine
                         $aspectContainer->addAdvisor($advisor);
                         break;
                     case Flow\AfterThrowing::class:
+                        /** @var Flow\AfterThrowing $annotation */
                         $pointcutFilterComposite = $this->pointcutExpressionParser->parse($annotation->pointcutExpression, $this->renderSourceHint($aspectClassName, $methodName, $annotationClass));
                         $advice = new Aop\Advice\AfterThrowingAdvice($aspectClassName, $methodName);
                         $pointcut = new Pointcut($annotation->pointcutExpression, $pointcutFilterComposite, $aspectClassName);
@@ -303,6 +322,7 @@ protected function buildAspectContainer(string $aspectClassName): AspectContaine
                         $aspectContainer->addAdvisor($advisor);
                         break;
                     case Flow\After::class:
+                        /** @var Flow\After $annotation */
                         $pointcutFilterComposite = $this->pointcutExpressionParser->parse($annotation->pointcutExpression, $this->renderSourceHint($aspectClassName, $methodName, $annotationClass));
                         $advice = new Aop\Advice\AfterAdvice($aspectClassName, $methodName);
                         $pointcut = new Pointcut($annotation->pointcutExpression, $pointcutFilterComposite, $aspectClassName);
@@ -310,6 +330,7 @@ protected function buildAspectContainer(string $aspectClassName): AspectContaine
                         $aspectContainer->addAdvisor($advisor);
                         break;
                     case Flow\Pointcut::class:
+                        /** @var Flow\Pointcut $annotation */
                         $pointcutFilterComposite = $this->pointcutExpressionParser->parse($annotation->expression, $this->renderSourceHint($aspectClassName, $methodName, $annotationClass));
                         $pointcut = new Pointcut($annotation->expression, $pointcutFilterComposite, $aspectClassName, $methodName);
                         $aspectContainer->addPointcut($pointcut);
@@ -358,8 +379,8 @@ protected function buildAspectContainer(string $aspectClassName): AspectContaine
     /**
      * Builds methods for a single AOP proxy class for the specified class.
      *
-     * @param string $targetClassName Name of the class to create a proxy class file for
-     * @param array $aspectContainers The array of aspect containers from the AOP Framework
+     * @param class-string $targetClassName Name of the class to create a proxy class file for
+     * @param array<AspectContainer> $aspectContainers The array of aspect containers from the AOP Framework
      * @return bool true if the proxy class could be built, false otherwise.
      * @throws \ReflectionException
      * @throws CannotBuildObjectException
@@ -379,7 +400,15 @@ public function buildProxyClass(string $targetClassName, array $aspectContainers
         $methodsFromIntroducedInterfaces = $this->getIntroducedMethodsFromInterfaceIntroductions($interfaceIntroductions);
 
         $interceptedMethods = [];
-        $this->addAdvisedMethodsToInterceptedMethods($interceptedMethods, array_merge($methodsFromTargetClass, $methodsFromIntroducedInterfaces), $targetClassName, $aspectContainers);
+        $this->addAdvisedMethodsToInterceptedMethods(
+            $interceptedMethods,
+            array_merge(
+                $methodsFromTargetClass,
+                $methodsFromIntroducedInterfaces
+            ),
+            $targetClassName,
+            $aspectContainers
+        );
         $this->addIntroducedMethodsToInterceptedMethods($interceptedMethods, $methodsFromIntroducedInterfaces);
 
         if (count($interceptedMethods) < 1 && count($introducedInterfaces) < 1 && count($introducedTraits) < 1 && count($propertyIntroductions) < 1) {
@@ -471,7 +500,7 @@ protected function proxySubClassesOfClassToEnsureAdvices(string $className, Clas
     /**
      * Adds code to build the methods and advices array in case the parent class has some.
      *
-     * @param string $className
+     * @param class-string $className
      * @param ClassNameIndex $treatedSubClasses
      * @return ClassNameIndex
      * @throws \ReflectionException
@@ -483,7 +512,7 @@ protected function addBuildMethodsAndAdvicesCodeToClass(string $className, Class
             return $treatedSubClasses;
         }
 
-        $treatedSubClasses = $treatedSubClasses->union(new ClassNameIndex([$className]));
+        $treatedSubClasses = $treatedSubClasses->union(new ClassNameIndex([$className => true])); // @fixme in 8.3+
         if ($this->reflectionService->isClassReflected($className) === false) {
             return $treatedSubClasses;
         }
@@ -503,8 +532,9 @@ protected function addBuildMethodsAndAdvicesCodeToClass(string $className, Class
     /**
      * Returns the methods of the target class.
      *
-     * @param string $targetClassName Name of the target class
-     * @return array Method information with declaring class and method name pairs
+     * @template T of object
+     * @param class-string<T> $targetClassName Name of the target class
+     * @return array<int,array{0: class-string<T>, 1: string}> Method information with declaring class and method name pairs
      * @throws \ReflectionException
      */
     protected function getMethodsFromTargetClass(string $targetClassName): array
@@ -539,7 +569,7 @@ protected function getMethodsFromTargetClass(string $targetClassName): array
      * 	);
      *
      *
-     * @param array $methodsAndGroupedAdvices An array of method names and grouped advice objects
+     * @param array<string,mixed> $methodsAndGroupedAdvices An array of method names and grouped advice objects
      * @return string PHP code for the content of an array of target method names and advice objects
      * @see buildProxyClass()
      */
@@ -574,8 +604,8 @@ protected function buildMethodsAndAdvicesArrayCode(array $methodsAndGroupedAdvic
      * The generated code is added directly to the proxy class by calling the respective
      * methods of the Compiler API.
      *
-     * @param string $targetClassName The target class the pointcut should match with
-     * @param array $interceptedMethods An array of method names which need to be intercepted
+     * @param class-string $targetClassName The target class the pointcut should match with
+     * @param array<string,array{groupedAdvices: array<mixed>}> $interceptedMethods An array of method names which need to be intercepted
      * @return void
      * @throws Aop\Exception\VoidImplementationException
      */
@@ -586,7 +616,11 @@ protected function buildMethodsInterceptorCode(string $targetClassName, array $i
                 throw new Aop\Exception\VoidImplementationException(sprintf('Refuse to introduce method %s into target class %s because it has no implementation code. You might want to create an around advice which implements this method.', $methodName, $targetClassName), 1303224472);
             }
             $builderType = 'Advised' . ($methodName === '__construct' ? 'Constructor' : 'Method');
-            $this->methodInterceptorBuilders[$builderType]->build($methodName, $interceptedMethods, $targetClassName);
+            $builder = $this->methodInterceptorBuilders[$builderType] ?? null;
+            if ($builder === null) {
+                throw new \RuntimeException('MethodInterceptorBuilder for ' . $builderType . ' not set', 1744496282);
+            }
+            $builder->build($methodName, $interceptedMethods, $targetClassName);
         }
     }
 
@@ -594,10 +628,10 @@ protected function buildMethodsInterceptorCode(string $targetClassName, array $i
      * Traverses all aspect containers, their aspects and their advisors and adds the
      * methods and their advices to the (usually empty) array of intercepted methods.
      *
-     * @param array &$interceptedMethods An array (empty or not) which contains the names of the intercepted methods and additional information
-     * @param array $methods An array of class and method names which are matched against the pointcut (class name = name of the class or interface the method was declared)
-     * @param string $targetClassName Name of the class the pointcut should match with
-     * @param array &$aspectContainers All aspects to take into consideration
+     * @param array<mixed> &$interceptedMethods An array (empty or not) which contains the names of the intercepted methods and additional information
+     * @param array<array{0: class-string, 1: string}> $methods An array of class and method names which are matched against the pointcut (class name = name of the class or interface the method was declared)
+     * @param class-string $targetClassName Name of the class the pointcut should match with
+     * @param array<AspectContainer> $aspectContainers All aspects to take into consideration
      * @return void
      */
     protected function addAdvisedMethodsToInterceptedMethods(array &$interceptedMethods, array $methods, string $targetClassName, array $aspectContainers): void
@@ -635,8 +669,8 @@ protected function addAdvisedMethodsToInterceptedMethods(array &$interceptedMeth
      * Traverses all methods which were introduced by interfaces and adds them to the
      * intercepted methods array if they didn't exist already.
      *
-     * @param array &$interceptedMethods An array (empty or not) which contains the names of the intercepted methods and additional information
-     * @param array $methodsFromIntroducedInterfaces An array of class and method names from introduced interfaces
+     * @param array<string,mixed> &$interceptedMethods An array (empty or not) which contains the names of the intercepted methods and additional information
+     * @param array<array{0: class-string, 1: string}> $methodsFromIntroducedInterfaces An array of class and method names from introduced interfaces
      * @return void
      */
     protected function addIntroducedMethodsToInterceptedMethods(array &$interceptedMethods, array $methodsFromIntroducedInterfaces): void
@@ -654,9 +688,9 @@ protected function addIntroducedMethodsToInterceptedMethods(array &$interceptedM
      * Traverses all aspect containers and returns an array of interface
      * introductions which match the target class.
      *
-     * @param array &$aspectContainers All aspects to take into consideration
-     * @param string $targetClassName Name of the class the pointcut should match with
-     * @return array array of interface names
+     * @param array<AspectContainer> $aspectContainers All aspects to take into consideration
+     * @param class-string $targetClassName Name of the class the pointcut should match with
+     * @return array<int,Aop\InterfaceIntroduction> array of interface names
      * @throws \Exception
      */
     protected function getMatchingInterfaceIntroductions(array $aspectContainers, string $targetClassName): array
@@ -680,9 +714,9 @@ protected function getMatchingInterfaceIntroductions(array $aspectContainers, st
      * Traverses all aspect containers and returns an array of property
      * introductions which match the target class.
      *
-     * @param array &$aspectContainers All aspects to take into consideration
-     * @param string $targetClassName Name of the class the pointcut should match with
-     * @return array|PropertyIntroduction[] array of property introductions
+     * @param array<AspectContainer> $aspectContainers All aspects to take into consideration
+     * @param class-string $targetClassName Name of the class the pointcut should match with
+     * @return array<int,PropertyIntroduction> array of property introductions
      * @throws \Exception
      */
     protected function getMatchingPropertyIntroductions(array $aspectContainers, string $targetClassName): array
@@ -706,24 +740,26 @@ protected function getMatchingPropertyIntroductions(array $aspectContainers, str
      * Traverses all aspect containers and returns an array of trait
      * introductions which match the target class.
      *
-     * @param array &$aspectContainers All aspects to take into consideration
-     * @param string $targetClassName Name of the class the pointcut should match with
-     * @return array array of trait names
+     * @param array<AspectContainer> $aspectContainers All aspects to take into consideration
+     * @param class-string $targetClassName Name of the class the pointcut should match with
+     * @return array<trait-string> array of trait names
      * @throws \Exception
      */
     protected function getMatchingTraitNamesFromIntroductions(array $aspectContainers, string $targetClassName): array
     {
         $introductions = [];
-        /** @var AspectContainer $aspectContainer */
         foreach ($aspectContainers as $aspectContainer) {
             if (!$aspectContainer->getCachedTargetClassNameCandidates()->hasClassName($targetClassName)) {
                 continue;
             }
-            /** @var TraitIntroduction $introduction */
             foreach ($aspectContainer->getTraitIntroductions() as $introduction) {
                 $pointcut = $introduction->getPointcut();
                 if ($pointcut->matches($targetClassName, null, null, Algorithms::generateRandomString(13))) {
-                    $introductions[] = '\\' . $introduction->getTraitName();
+                    $traitName = '\\' . $introduction->getTraitName();
+                    if (!trait_exists($traitName)) {
+                        throw new \InvalidArgumentException('Invalid trait name ' . $traitName, 1744493032);
+                    }
+                    $introductions[] = $traitName;
                 }
             }
         }
@@ -734,14 +770,18 @@ protected function getMatchingTraitNamesFromIntroductions(array $aspectContainer
     /**
      * Returns an array of interface names introduced by the given introductions
      *
-     * @param array $interfaceIntroductions An array of interface introductions
-     * @return array Array of interface names
+     * @param array<Aop\InterfaceIntroduction> $interfaceIntroductions An array of interface introductions
+     * @return array<int,class-string> Array of interface names
      */
     protected function getInterfaceNamesFromIntroductions(array $interfaceIntroductions): array
     {
         $interfaceNames = [];
         foreach ($interfaceIntroductions as $introduction) {
-            $interfaceNames[] = '\\' . $introduction->getInterfaceName();
+            $interfaceName = '\\' . $introduction->getInterfaceName();
+            if (!interface_exists($interfaceName)) {
+                throw new \InvalidArgumentException('Invalid interface name ' . $interfaceName, 1744492473);
+            }
+            $interfaceNames[] = $interfaceName;
         }
         return $interfaceNames;
     }
@@ -749,8 +789,8 @@ protected function getInterfaceNamesFromIntroductions(array $interfaceIntroducti
     /**
      * Returns all methods declared by the introduced interfaces
      *
-     * @param array $interfaceIntroductions An array of Aop\InterfaceIntroduction
-     * @return array An array of method information (interface, method name)
+     * @param array<Aop\InterfaceIntroduction> $interfaceIntroductions An array of Aop\InterfaceIntroduction
+     * @return array<int,array{0: class-string, 1: string}> An array of method information (interface, method name)
      * @throws Aop\Exception
      */
     protected function getIntroducedMethodsFromInterfaceIntroductions(array $interfaceIntroductions): array
diff --git a/Neos.Flow/Classes/Aop/InterfaceIntroduction.php b/Neos.Flow/Classes/Aop/InterfaceIntroduction.php
index fbbac0183d..a7e6198332 100644
--- a/Neos.Flow/Classes/Aop/InterfaceIntroduction.php
+++ b/Neos.Flow/Classes/Aop/InterfaceIntroduction.php
@@ -21,13 +21,13 @@ class InterfaceIntroduction
 {
     /**
      * Name of the aspect declaring this introduction
-     * @var string
+     * @var class-string
      */
     protected $declaringAspectClassName;
 
     /**
      * Name of the introduced interface
-     * @var string
+     * @var class-string
      */
     protected $interfaceName;
 
@@ -40,8 +40,8 @@ class InterfaceIntroduction
     /**
      * Constructor
      *
-     * @param string $declaringAspectClassName Name of the aspect containing the declaration for this introduction
-     * @param string $interfaceName Name of the interface to introduce
+     * @param class-string $declaringAspectClassName Name of the aspect containing the declaration for this introduction
+     * @param class-string $interfaceName Name of the interface to introduce
      * @param Pointcut $pointcut The pointcut for this introduction
      */
     public function __construct(string $declaringAspectClassName, string $interfaceName, Pointcut $pointcut)
@@ -54,7 +54,7 @@ public function __construct(string $declaringAspectClassName, string $interfaceN
     /**
      * Returns the name of the introduced interface
      *
-     * @return string Name of the introduced interface
+     * @return class-string Name of the introduced interface
      */
     public function getInterfaceName(): string
     {
@@ -74,7 +74,7 @@ public function getPointcut(): Pointcut
     /**
      * Returns the object name of the aspect which declared this introduction
      *
-     * @return string The aspect object name
+     * @return class-string The aspect object name
      */
     public function getDeclaringAspectClassName(): string
     {
diff --git a/Neos.Flow/Classes/Aop/JoinPoint.php b/Neos.Flow/Classes/Aop/JoinPoint.php
index dc1d6e4151..ebe29b006e 100644
--- a/Neos.Flow/Classes/Aop/JoinPoint.php
+++ b/Neos.Flow/Classes/Aop/JoinPoint.php
@@ -41,13 +41,13 @@ class JoinPoint implements JoinPointInterface
 
     /**
      * Array of method arguments which have been passed to the target method
-     * @var array
+     * @var array<string,mixed>
      */
     protected $methodArguments;
 
     /**
      * The advice chain for this join point
-     * @var Advice\AdviceChain
+     * @var Advice\AdviceChain|null
      */
     protected $adviceChain;
 
@@ -59,7 +59,7 @@ class JoinPoint implements JoinPointInterface
 
     /**
      * The exception thrown (only used for After Throwing advices)
-     * @var \Exception
+     * @var \Exception|null
      */
     protected $exception = null;
 
@@ -69,10 +69,10 @@ class JoinPoint implements JoinPointInterface
      * @param object $proxy Reference to the proxy class instance of the target class
      * @param string $className Class name of the target class this join point refers to
      * @param string $methodName Method name of the target method which is about to or has been invoked
-     * @param array $methodArguments Array of method arguments which have been passed to the target method
-     * @param Advice\AdviceChain $adviceChain The advice chain for this join point
+     * @param array<mixed> $methodArguments Array of method arguments which have been passed to the target method
+     * @param Advice\AdviceChain|null $adviceChain The advice chain for this join point
      * @param mixed $result The result of the method invocations (only used for After Returning advices)
-     * @param \Exception $exception The exception thrown (only used for After Throwing advices)
+     * @param \Exception|null $exception The exception thrown (only used for After Throwing advices)
      */
     public function __construct($proxy, string $className, string $methodName, array $methodArguments, ?Advice\AdviceChain $adviceChain = null, $result = null, ?\Exception $exception = null)
     {
@@ -121,7 +121,7 @@ public function getMethodName(): string
     /**
      * Returns an array of arguments which have been passed to the target method
      *
-     * @return array Array of arguments
+     * @return array<string,mixed> Array of arguments
      * @api
      */
     public function getMethodArguments(): array
@@ -178,10 +178,10 @@ public function isMethodArgument($argumentName): bool
     /**
      * Returns the advice chain related to this join point
      *
-     * @return Advice\AdviceChain The advice chain
+     * @return ?Advice\AdviceChain The advice chain
      * @api
      */
-    public function getAdviceChain(): Advice\AdviceChain
+    public function getAdviceChain(): ?Advice\AdviceChain
     {
         return $this->adviceChain;
     }
diff --git a/Neos.Flow/Classes/Aop/JoinPointInterface.php b/Neos.Flow/Classes/Aop/JoinPointInterface.php
index 56f27290c1..5718096f91 100644
--- a/Neos.Flow/Classes/Aop/JoinPointInterface.php
+++ b/Neos.Flow/Classes/Aop/JoinPointInterface.php
@@ -41,7 +41,7 @@ public function getMethodName();
     /**
      * Returns an array of arguments which have been passed to the target method
      *
-     * @return array Array of arguments
+     * @return array<string,mixed> Array of arguments
      */
     public function getMethodArguments();
 
@@ -82,6 +82,7 @@ public function getAdviceChain();
      * If an exception was thrown by the target method
      * Only makes sense for After Throwing advices.
      *
+     * @phpstan-assert-if-true !null $this->getException()
      * @return boolean
      */
     public function hasException();
@@ -91,6 +92,7 @@ public function hasException();
      * If no exception has been thrown, NULL is returned.
      * Only makes sense for After Throwing advices.
      *
+     *
      * @return \Exception|null The exception thrown or NULL
      */
     public function getException();
diff --git a/Neos.Flow/Classes/Aop/Pointcut/Pointcut.php b/Neos.Flow/Classes/Aop/Pointcut/Pointcut.php
index 7322b398d2..325552011b 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/Pointcut.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/Pointcut.php
@@ -41,13 +41,13 @@ class Pointcut implements PointcutFilterInterface
 
     /**
      * If this pointcut is based on a pointcut declaration, contains the name of the aspect class where the pointcut was declared
-     * @var string
+     * @var class-string
      */
-    protected $aspectClassName;
+    protected string $aspectClassName;
 
     /**
      * If this pointcut is based on a pointcut declaration, contains the name of the method acting as the pointcut identifier
-     * @var string
+     * @var ?string
      */
     protected $pointcutMethodName;
 
@@ -68,8 +68,8 @@ class Pointcut implements PointcutFilterInterface
      *
      * @param string $pointcutExpression A pointcut expression which configures the pointcut
      * @param PointcutFilterComposite $pointcutFilterComposite
-     * @param string $aspectClassName The name of the aspect class where the pointcut was declared (either explicitly or from an advice's pointcut expression)
-     * @param string $pointcutMethodName (optional) If the pointcut is created from a pointcut declaration, the name of the method declaring the pointcut must be passed
+     * @param class-string $aspectClassName The name of the aspect class where the pointcut was declared (either explicitly or from an advice's pointcut expression)
+     * @param ?string $pointcutMethodName (optional) If the pointcut is created from a pointcut declaration, the name of the method declaring the pointcut must be passed
      */
     public function __construct(string $pointcutExpression, PointcutFilterComposite $pointcutFilterComposite, string $aspectClassName, ?string $pointcutMethodName = null)
     {
@@ -83,9 +83,9 @@ public function __construct(string $pointcutExpression, PointcutFilterComposite
      * Checks if the given class and method match this pointcut.
      * Before each match run, reset() must be called to reset the circular references guard.
      *
-     * @param string $className Class to check against
-     * @param string $methodName Method to check against
-     * @param string $methodDeclaringClassName Name of the class the method was originally declared in
+     * @param class-string $className Class to check against
+     * @param ?string $methodName Method to check against
+     * @param ?class-string $methodDeclaringClassName Name of the class the method was originally declared in
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
      * @return boolean true if class and method match this point cut, otherwise false
      * @throws CircularPointcutReferenceException if a circular pointcut reference was detected
@@ -119,7 +119,7 @@ public function getPointcutExpression(): string
     /**
      * Returns the aspect class name where the pointcut was declared.
      *
-     * @return string The aspect class name where the pointcut was declared
+     * @return class-string The aspect class name where the pointcut was declared
      */
     public function getAspectClassName(): string
     {
@@ -129,9 +129,9 @@ public function getAspectClassName(): string
     /**
      * Returns the pointcut method name (if any was defined)
      *
-     * @return string The pointcut method name
+     * @return ?string The pointcut method name
      */
-    public function getPointcutMethodName(): string
+    public function getPointcutMethodName(): ?string
     {
         return $this->pointcutMethodName;
     }
@@ -149,7 +149,7 @@ public function hasRuntimeEvaluationsDefinition(): bool
     /**
      * Returns runtime evaluations for the pointcut.
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition(): array
     {
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutClassAnnotatedWithFilter.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutClassAnnotatedWithFilter.php
index aff5b775ed..f979259464 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutClassAnnotatedWithFilter.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutClassAnnotatedWithFilter.php
@@ -34,20 +34,20 @@ class PointcutClassAnnotatedWithFilter implements PointcutFilterInterface
     protected $logger;
 
     /**
-     * @var string A regular expression to match annotations
+     * @var class-string<object> An annotation class (for example "@Neos\Flow\Annotations\Aspect") which defines which class annotations should match
      */
     protected $annotation;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $annotationValueConstraints;
 
     /**
      * The constructor - initializes the class annotation filter with the expected annotation class
      *
-     * @param string $annotation An annotation class (for example "@Neos\Flow\Annotations\Aspect") which defines which class annotations should match
-     * @param array $annotationValueConstraints
+     * @param class-string<object> $annotation An annotation class (for example "@Neos\Flow\Annotations\Aspect") which defines which class annotations should match
+     * @param array<mixed> $annotationValueConstraints
      */
     public function __construct(string $annotation, array $annotationValueConstraints = [])
     {
@@ -80,9 +80,9 @@ public function injectLogger(LoggerInterface $logger)
     /**
      * Checks if the specified class matches with the class tag filter pattern
      *
-     * @param string $className Name of the class to check against
+     * @param class-string<object> $className Name of the class to check against
      * @param string $methodName Name of the method - not used here
-     * @param string $methodDeclaringClassName Name of the class the method was originally declared in - not used here
+     * @param class-string<object> $methodDeclaringClassName Name of the class the method was originally declared in - not used here
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
      * @return bool true if the class matches, otherwise false
      */
@@ -126,7 +126,7 @@ public function hasRuntimeEvaluationsDefinition(): bool
     /**
      * Returns runtime evaluations for the pointcut.
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition(): array
     {
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutClassNameFilter.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutClassNameFilter.php
index a299206c0b..c338a5cd11 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutClassNameFilter.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutClassNameFilter.php
@@ -97,7 +97,7 @@ public function hasRuntimeEvaluationsDefinition(): bool
     /**
      * Returns runtime evaluations for the pointcut.
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition(): array
     {
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutClassTypeFilter.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutClassTypeFilter.php
index fe0b39a22c..7aea7f3995 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutClassTypeFilter.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutClassTypeFilter.php
@@ -30,7 +30,7 @@ class PointcutClassTypeFilter implements PointcutFilterInterface
 
     /**
      * An interface name to match class types
-     * @var string
+     * @var class-string<object>
      */
     protected $interfaceOrClassName;
 
@@ -43,7 +43,7 @@ class PointcutClassTypeFilter implements PointcutFilterInterface
     /**
      * The constructor - initializes the class type filter with the class or interface name
      *
-     * @param string $interfaceOrClassName Interface or a class name to match against
+     * @param class-string $interfaceOrClassName Interface or a class name to match against
      * @throws Exception
      */
     public function __construct(string $interfaceOrClassName)
@@ -71,19 +71,16 @@ public function injectReflectionService(ReflectionService $reflectionService): v
     /**
      * Checks if the specified class matches with the class type filter
      *
-     * @param string $className Name of the class to check against
+     * @param class-string<object> $className Name of the class to check against
      * @param string $methodName Name of the method - not used here
-     * @param string $methodDeclaringClassName Name of the class the method was originally declared in - not used here
+     * @param class-string<object> $methodDeclaringClassName Name of the class the method was originally declared in - not used here
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
      * @return boolean true if the class matches, otherwise false
      */
     public function matches($className, $methodName, $methodDeclaringClassName, $pointcutQueryIdentifier): bool
     {
-        if ($this->isInterface === true) {
-            return (array_search($this->interfaceOrClassName, class_implements($className)) !== false);
-        } else {
-            return ($className === $this->interfaceOrClassName || is_subclass_of($className, $this->interfaceOrClassName));
-        }
+        return $className === $this->interfaceOrClassName
+            || is_subclass_of($className, $this->interfaceOrClassName);
     }
 
     /**
@@ -99,7 +96,7 @@ public function hasRuntimeEvaluationsDefinition(): bool
     /**
      * Returns runtime evaluations for the pointcut.
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition(): array
     {
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutExpressionParser.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutExpressionParser.php
index a10cec36d9..64656b7ac3 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutExpressionParser.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutExpressionParser.php
@@ -26,6 +26,16 @@
  * from a pointcut- or advice annotation and returns a pointcut filter composite.
  *
  * @see \Neos\Flow\Aop\Pointcut, PointcutFilterComposite
+ *
+ * @phpstan-type ArgumentConstraints array<string,array{
+ *      operator: array<int,string>,
+ *      value: array<int,mixed>,
+ * }>
+ * @phpstan-type RuntimeEvaluationCondition array{
+ *      operator: string,
+ *      leftValue: string,
+ *      rightValue: mixed,
+ * }
  * @Flow\Scope("singleton")
  * @Flow\Proxy(false)
  */
@@ -123,11 +133,11 @@ public function parse(string $pointcutExpression, string $sourceHint): PointcutF
     {
         $this->sourceHint = $sourceHint;
 
-        if (!is_string($pointcutExpression) || strlen($pointcutExpression) === 0) {
+        if (strlen($pointcutExpression) === 0) {
             throw new InvalidPointcutExpressionException(sprintf('Pointcut expression must be a valid string, "%s" given, defined in "%s"', gettype($pointcutExpression), $this->sourceHint), 1168874738);
         }
         $pointcutFilterComposite = new PointcutFilterComposite();
-        $pointcutExpressionParts = preg_split(self::PATTERN_SPLITBYOPERATOR, $pointcutExpression, -1, PREG_SPLIT_DELIM_CAPTURE);
+        $pointcutExpressionParts = preg_split(self::PATTERN_SPLITBYOPERATOR, $pointcutExpression, -1, PREG_SPLIT_DELIM_CAPTURE) ?: [];
 
         $count = count($pointcutExpressionParts);
         for ($partIndex = 0; $partIndex < $count; $partIndex += 2) {
@@ -158,6 +168,7 @@ public function parse(string $pointcutExpression, string $sourceHint): PointcutF
                     case 'filter':
                     case 'setting':
                         $parseMethodName = 'parseDesignator' . ucfirst($pointcutDesignator);
+                        /** @phpstan-ignore argument.type, argument.type, argument.type (I guess we excluded empty string for class names here, already) */
                         $this->$parseMethodName($operator, $signaturePattern, $pointcutFilterComposite);
                         break;
                     case 'evaluate':
@@ -176,7 +187,7 @@ public function parse(string $pointcutExpression, string $sourceHint): PointcutF
      * filter composite object.
      *
      * @param string $operator The operator
-     * @param string $annotationPattern The pattern expression as configuration for the class annotation filter
+     * @param class-string<object> $annotationPattern The pattern expression as configuration for the class annotation filter
      * @param PointcutFilterComposite $pointcutFilterComposite An instance of the pointcut filter composite. The result (ie. the class annotation filter) will be added to this composite object.
      * @return void
      */
@@ -184,6 +195,9 @@ protected function parseDesignatorClassAnnotatedWith(string $operator, string $a
     {
         $annotationPropertyConstraints = [];
         $this->parseAnnotationPattern($annotationPattern, $annotationPropertyConstraints);
+        if (!class_exists($annotationPattern)) {
+            throw new \InvalidArgumentException('Cannot resolve annotation pattern class ' . $annotationPattern, 1744491903);
+        }
 
         $filter = new PointcutClassAnnotatedWithFilter($annotationPattern, $annotationPropertyConstraints);
         $filter->injectReflectionService($this->reflectionService);
@@ -212,7 +226,7 @@ protected function parseDesignatorClass(string $operator, string $classPattern,
      * filter composite object.
      *
      * @param string $operator The operator
-     * @param string $annotationPattern The pattern expression as configuration for the method annotation filter
+     * @param class-string $annotationPattern The pattern expression as configuration for the method annotation filter
      * @param PointcutFilterComposite $pointcutFilterComposite An instance of the pointcut filter composite. The result (ie. the method annotation filter) will be added to this composite object.
      * @return void
      */
@@ -221,6 +235,9 @@ protected function parseDesignatorMethodAnnotatedWith(string $operator, string $
         $annotationPropertyConstraints = [];
         $this->parseAnnotationPattern($annotationPattern, $annotationPropertyConstraints);
 
+        if (!class_exists($annotationPattern)) {
+            throw new \InvalidArgumentException('Invalid annotation pattern ' . $annotationPattern . ', must be an existing class', 1744490385);
+        }
         $filter = new PointcutMethodAnnotatedWithFilter($annotationPattern, $annotationPropertyConstraints);
         $filter->injectReflectionService($this->reflectionService);
         $filter->injectLogger($this->objectManager->get(PsrLoggerFactoryInterface::class)->get('systemLogger'));
@@ -232,7 +249,8 @@ protected function parseDesignatorMethodAnnotatedWith(string $operator, string $
      * needed.
      *
      * @param string $annotationPattern
-     * @param array $annotationPropertyConstraints
+     * @param array<mixed> $annotationPropertyConstraints
+     *
      * @return void
      */
     protected function parseAnnotationPattern(string &$annotationPattern, array &$annotationPropertyConstraints): void
@@ -241,8 +259,8 @@ protected function parseAnnotationPattern(string &$annotationPattern, array &$an
             $matches = [];
             preg_match(self::PATTERN_MATCHMETHODNAMEANDARGUMENTS, $annotationPattern, $matches);
 
-            $annotationPattern = $matches['MethodName'];
-            $annotationPropertiesPattern = $matches['MethodArguments'];
+            $annotationPattern = $matches['MethodName'] ?? '';
+            $annotationPropertiesPattern = $matches['MethodArguments'] ?? '';
             $annotationPropertyConstraints = $this->getArgumentConstraintsFromMethodArgumentsPattern($annotationPropertiesPattern);
         }
     }
@@ -272,8 +290,8 @@ protected function parseDesignatorMethod(string $operator, string $signaturePatt
         $matches = [];
         preg_match(self::PATTERN_MATCHMETHODNAMEANDARGUMENTS, $methodPattern, $matches);
 
-        $methodNamePattern = $matches['MethodName'];
-        $methodArgumentPattern = $matches['MethodArguments'];
+        $methodNamePattern = $matches['MethodName'] ?? '';
+        $methodArgumentPattern = $matches['MethodArguments'] ?? '';
         $methodArgumentConstraints = $this->getArgumentConstraintsFromMethodArgumentsPattern($methodArgumentPattern);
 
         $classNameFilter = new PointcutClassNameFilter($classPattern);
@@ -299,8 +317,9 @@ protected function parseDesignatorMethod(string $operator, string $signaturePatt
      * Adds a class type filter to the pointcut filter composite
      *
      * @param string $operator
-     * @param string $signaturePattern The pattern expression defining the class type
+     * @param class-string $signaturePattern The pattern expression defining the class type
      * @param PointcutFilterComposite $pointcutFilterComposite An instance of the pointcut filter composite. The result (ie. the class type filter) will be added to this composite object.
+     * @todo this is only ever called from tests, do we even need this?
      * @return void
      */
     protected function parseDesignatorWithin(string $operator, string $signaturePattern, PointcutFilterComposite $pointcutFilterComposite): void
@@ -452,7 +471,7 @@ protected function getVisibilityFromSignaturePattern(string &$signaturePattern)
      * Parses the method arguments pattern and returns the corresponding constraints array
      *
      * @param string $methodArgumentsPattern The arguments pattern defined in the pointcut expression
-     * @return array The corresponding constraints array
+     * @return ArgumentConstraints The corresponding constraints array
      */
     protected function getArgumentConstraintsFromMethodArgumentsPattern(string $methodArgumentsPattern): array
     {
@@ -467,7 +486,7 @@ protected function getArgumentConstraintsFromMethodArgumentsPattern(string $meth
                 $list = [];
                 $listEntries = [];
 
-                if (preg_match('/^\s*\(.*\)\s*$/', $matches[3][$i], $list) > 0) {
+                if (is_string($matches[3][$i]) && preg_match('/^\s*\(.*\)\s*$/', $matches[3][$i], $list) > 0) {
                     preg_match_all(self::PATTERN_MATCHRUNTIMEEVALUATIONSVALUELIST, $list[0], $listEntries);
                     $matches[3][$i] = $listEntries[1];
                 }
@@ -483,7 +502,7 @@ protected function getArgumentConstraintsFromMethodArgumentsPattern(string $meth
      * Parses the evaluate string for runtime evaluations and returns the corresponding conditions array
      *
      * @param string $evaluateString The evaluate string defined in the pointcut expression
-     * @return array The corresponding constraints array
+     * @return array<int,RuntimeEvaluationCondition> The corresponding constraints array
      */
     protected function getRuntimeEvaluationConditionsFromEvaluateString(string $evaluateString): array
     {
@@ -498,7 +517,7 @@ protected function getRuntimeEvaluationConditionsFromEvaluateString(string $eval
                 $list = [];
                 $listEntries = [];
 
-                if (preg_match('/^\s*\(.*\)\s*$/', $matches[3][$i], $list) > 0) {
+                if (is_string($matches[3][$i]) && preg_match('/^\s*\(.*\)\s*$/', $matches[3][$i], $list) > 0) {
                     preg_match_all(self::PATTERN_MATCHRUNTIMEEVALUATIONSVALUELIST, $list[0], $listEntries);
                     $matches[3][$i] = $listEntries[1];
                 }
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutFilter.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutFilter.php
index 059819d8b8..dd258bce43 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutFilter.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutFilter.php
@@ -73,9 +73,9 @@ public function injectProxyClassBuilder(ProxyClassBuilder $proxyClassBuilder): v
     /**
      * Checks if the specified class and method matches with the pointcut
      *
-     * @param string $className Name of the class to check against
+     * @param class-string $className Name of the class to check against
      * @param string $methodName Name of the method - not used here
-     * @param string $methodDeclaringClassName Name of the class the method was originally declared in
+     * @param class-string $methodDeclaringClassName Name of the class the method was originally declared in
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
      * @return boolean true if the class matches, otherwise false
      * @throws UnknownPointcutException
@@ -104,7 +104,7 @@ public function hasRuntimeEvaluationsDefinition(): bool
     /**
      * Returns runtime evaluations for the pointcut.
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition(): array
     {
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutFilterComposite.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutFilterComposite.php
index 699e72df63..0279d0bd5b 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutFilterComposite.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutFilterComposite.php
@@ -27,7 +27,7 @@
 class PointcutFilterComposite implements PointcutFilterInterface
 {
     /**
-     * @var array An array of \Neos\Flow\Aop\Pointcut\Pointcut*Filter objects
+     * @var array<mixed> An array of \Neos\Flow\Aop\Pointcut\Pointcut*Filter objects
      */
     protected $filters = [];
 
@@ -37,12 +37,12 @@ class PointcutFilterComposite implements PointcutFilterInterface
     protected $earlyReturn = true;
 
     /**
-     * @var array An array of runtime evaluations
+     * @var array<mixed> An array of runtime evaluations
      */
     protected $runtimeEvaluationsDefinition = [];
 
     /**
-     * @var array An array of global runtime evaluations
+     * @var array<mixed> An array of global runtime evaluations
      */
     protected $globalRuntimeEvaluationsDefinition = [];
 
@@ -50,9 +50,9 @@ class PointcutFilterComposite implements PointcutFilterInterface
      * Checks if the specified class and method match the registered class-
      * and method filter patterns.
      *
-     * @param string $className Name of the class to check against
-     * @param string $methodName Name of the method to check against
-     * @param string $methodDeclaringClassName Name of the class the method was originally declared in
+     * @param class-string $className Name of the class to check against
+     * @param ?string $methodName Name of the method to check against
+     * @param ?class-string $methodDeclaringClassName Name of the class the method was originally declared in
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
      * @return boolean true if class and method match the pattern, otherwise false
      */
@@ -143,7 +143,7 @@ public function hasRuntimeEvaluationsDefinition()
     /**
      * Returns runtime evaluations for the pointcut.
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition()
     {
@@ -154,7 +154,7 @@ public function getRuntimeEvaluationsDefinition()
      * Sets static runtime evaluations for to pointcut, that will be used for every
      * method this composite matches
      *
-     * @param array $runtimeEvaluations Runtime evaluations to be added
+     * @param array<mixed> $runtimeEvaluations Runtime evaluations to be added
      * @return void
      */
     public function setGlobalRuntimeEvaluationsDefinition(array $runtimeEvaluations): void
@@ -214,7 +214,7 @@ public function reduceTargetClassNames(ClassNameIndex $classNameIndex)
      * Returns the PHP code of the conditions used for runtime evaluations
      *
      * @param string $operator The operator for the given condition
-     * @param array $conditions Condition array
+     * @param array<string,mixed> $conditions Condition array
      * @param boolean &$useGlobalObjects Set to true if global objects are used by the condition
      * @return string The condition code
      */
@@ -289,7 +289,10 @@ protected function buildRuntimeEvaluationsConditionCode($operator, array $condit
     /**
      * Returns the PHP code of the conditions used argument runtime evaluations
      *
-     * @param array $conditions Condition array
+     * @param array<string,array{
+     *      operator: array<int,string>,
+     *      value: array<int,string>,
+     *  }> $conditions Condition array
      * @param boolean &$useGlobalObjects Set to true if global objects are used by the condition
      * @return string The arguments condition code
      */
@@ -329,7 +332,11 @@ protected function buildMethodArgumentsEvaluationConditionCode(array $conditions
     /**
      * Returns the PHP code of the conditions used for global runtime evaluations
      *
-     * @param array $conditions Condition array
+     * @param array<array{
+     *     leftValue: string,
+     *     operator: string,
+     *     rightValue: string,
+     * }> $conditions Condition array
      * @param boolean &$useGlobalObjects Set to true if global objects are used by the condition
      * @return string The condition code
      */
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutFilterInterface.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutFilterInterface.php
index fdebcdfd95..2464fae7b2 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutFilterInterface.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutFilterInterface.php
@@ -24,9 +24,9 @@ interface PointcutFilterInterface
     /**
      * Checks if the specified class and method matches against the filter
      *
-     * @param string $className Name of the class to check against
+     * @param class-string $className Name of the class to check against
      * @param string $methodName Name of the method to check against
-     * @param string $methodDeclaringClassName Name of the class the method was originally declared in
+     * @param class-string $methodDeclaringClassName Name of the class the method was originally declared in
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
      * @return boolean true if the class / method match, otherwise false
      */
@@ -42,7 +42,7 @@ public function hasRuntimeEvaluationsDefinition();
     /**
      * Returns runtime evaluations for a previously matched pointcut
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition();
 
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodAnnotatedWithFilter.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodAnnotatedWithFilter.php
index ba44576a91..7a121d1ee0 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodAnnotatedWithFilter.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodAnnotatedWithFilter.php
@@ -33,22 +33,21 @@ class PointcutMethodAnnotatedWithFilter implements PointcutFilterInterface
      */
     protected $logger;
 
-
     /**
-     * @var string The tag of an annotation to match against
+     * @var class-string<object> The tag of an annotation to match against
      */
-    protected $annotation;
+    protected string $annotation;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $annotationValueConstraints;
 
     /**
      * The constructor - initializes the method annotation filter with the expected annotation class
      *
-     * @param string $annotation An annotation class (for example "Neos\Flow\Annotations\Lazy") which defines which method annotations should match
-     * @param array $annotationValueConstraints
+     * @param class-string<object> $annotation An annotation class (for example "Neos\Flow\Annotations\Lazy") which defines which method annotations should match
+     * @param array<mixed> $annotationValueConstraints
      */
     public function __construct(string $annotation, array $annotationValueConstraints = [])
     {
@@ -81,15 +80,15 @@ public function injectLogger(LoggerInterface $logger)
     /**
      * Checks if the specified method matches with the method annotation filter pattern
      *
-     * @param string $className Name of the class to check against - not used here
+     * @param class-string $className Name of the class to check against - not used here
      * @param string $methodName Name of the method
-     * @param string $methodDeclaringClassName Name of the class the method was originally declared in
+     * @param class-string $methodDeclaringClassName Name of the class the method was originally declared in
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection - not used here
      * @return boolean true if the class matches, otherwise false
      */
     public function matches($className, $methodName, $methodDeclaringClassName, $pointcutQueryIdentifier): bool
     {
-        if ($methodDeclaringClassName === null || !method_exists($methodDeclaringClassName, $methodName)) {
+        if (!method_exists($methodDeclaringClassName, $methodName)) {
             return false;
         }
 
@@ -128,7 +127,7 @@ public function hasRuntimeEvaluationsDefinition(): bool
     /**
      * Returns runtime evaluations for the pointcut.
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition(): array
     {
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodNameFilter.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodNameFilter.php
index 0c03d3ef2e..6bad8e9f21 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodNameFilter.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutMethodNameFilter.php
@@ -48,7 +48,7 @@ class PointcutMethodNameFilter implements PointcutFilterInterface
     protected $logger;
 
     /**
-     * @var array Array with constraints for method arguments
+     * @var array<mixed> Array with constraints for method arguments
      */
     protected $methodArgumentConstraints = [];
 
@@ -57,7 +57,7 @@ class PointcutMethodNameFilter implements PointcutFilterInterface
      *
      * @param string $methodNameFilterExpression A regular expression which filters method names
      * @param string|null $methodVisibility The method visibility modifier (public, protected or private). Specify NULL if you don't care.
-     * @param array $methodArgumentConstraints array of method constraints
+     * @param array<mixed> $methodArgumentConstraints array of method constraints
      * @throws InvalidPointcutExpressionException
      */
     public function __construct(string $methodNameFilterExpression, ?string $methodVisibility = null, array $methodArgumentConstraints = [])
@@ -98,9 +98,9 @@ public function injectLogger(LoggerInterface $logger)
      *
      * Returns true if method name, visibility and arguments constraints match.
      *
-     * @param string $className Ignored in this pointcut filter
+     * @param class-string $className Ignored in this pointcut filter
      * @param string $methodName Name of the method to match against
-     * @param string $methodDeclaringClassName Name of the class the method was originally declared in
+     * @param class-string $methodDeclaringClassName Name of the class the method was originally declared in
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
      * @return boolean true if the class matches, otherwise false
      * @throws Exception
@@ -117,18 +117,18 @@ public function matches($className, $methodName, $methodDeclaringClassName, $poi
 
         switch ($this->methodVisibility) {
             case 'public':
-                if (!($methodDeclaringClassName !== null && $this->reflectionService->isMethodPublic($methodDeclaringClassName, $methodName))) {
+                if (!($this->reflectionService->isMethodPublic($methodDeclaringClassName, $methodName))) {
                     return false;
                 }
                 break;
             case 'protected':
-                if (!($methodDeclaringClassName !== null && $this->reflectionService->isMethodProtected($methodDeclaringClassName, $methodName))) {
+                if (!($this->reflectionService->isMethodProtected($methodDeclaringClassName, $methodName))) {
                     return false;
                 }
                 break;
         }
 
-        $methodArguments = ($methodDeclaringClassName === null ? [] : $this->reflectionService->getMethodParameters($methodDeclaringClassName, $methodName));
+        $methodArguments = $this->reflectionService->getMethodParameters($methodDeclaringClassName, $methodName);
         foreach (array_keys($this->methodArgumentConstraints) as $argumentName) {
             $objectAccess = explode('.', $argumentName, 2);
             $argumentName = $objectAccess[0];
@@ -153,7 +153,7 @@ public function hasRuntimeEvaluationsDefinition(): bool
     /**
      * Returns runtime evaluations for a previously matched pointcut
      *
-     * @return array Runtime evaluations
+     * @return array{methodArgumentConstraints: array<mixed>} Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition(): array
     {
@@ -185,7 +185,7 @@ public function getMethodVisibility(): ?string
     /**
      * Returns the method argument constraints
      *
-     * @return array
+     * @return array<mixed>
      */
     public function getMethodArgumentConstraints(): array
     {
diff --git a/Neos.Flow/Classes/Aop/Pointcut/PointcutSettingFilter.php b/Neos.Flow/Classes/Aop/Pointcut/PointcutSettingFilter.php
index ec0f390f95..ef2a26a60e 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/PointcutSettingFilter.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/PointcutSettingFilter.php
@@ -109,7 +109,7 @@ public function hasRuntimeEvaluationsDefinition(): bool
     /**
      * Returns runtime evaluations for the pointcut.
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition(): array
     {
@@ -126,7 +126,7 @@ public function getRuntimeEvaluationsDefinition(): array
      */
     protected function parseConfigurationOptionPath(string $settingComparisonExpression): void
     {
-        $settingComparisonExpression = preg_split(self::PATTERN_SPLITBYEQUALSIGN, $settingComparisonExpression);
+        $settingComparisonExpression = preg_split(self::PATTERN_SPLITBYEQUALSIGN, $settingComparisonExpression) ?: [];
         if (isset($settingComparisonExpression[1])) {
             $matches = [];
             preg_match(self::PATTERN_MATCHVALUEINQUOTES, $settingComparisonExpression[1], $matches);
@@ -141,6 +141,7 @@ protected function parseConfigurationOptionPath(string $settingComparisonExpress
 
         $configurationKeys = explode('.', $settingComparisonExpression[0]);
 
+        /** @phpstan-ignore greater.alwaysTrue (not sure about this) */
         if (count($configurationKeys) > 0) {
             $settingPackageKey = array_shift($configurationKeys);
             $settingValue = $this->configurationManager->getConfiguration(ConfigurationManager::CONFIGURATION_TYPE_SETTINGS, $settingPackageKey);
diff --git a/Neos.Flow/Classes/Aop/Pointcut/RuntimeExpressionEvaluator.php b/Neos.Flow/Classes/Aop/Pointcut/RuntimeExpressionEvaluator.php
index ffd7b3483e..decb3660b9 100644
--- a/Neos.Flow/Classes/Aop/Pointcut/RuntimeExpressionEvaluator.php
+++ b/Neos.Flow/Classes/Aop/Pointcut/RuntimeExpressionEvaluator.php
@@ -40,7 +40,7 @@ class RuntimeExpressionEvaluator
     /**
      * Currently existing runtime expressions loaded from cache.
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected $runtimeExpressions = [];
 
diff --git a/Neos.Flow/Classes/Aop/PropertyIntroduction.php b/Neos.Flow/Classes/Aop/PropertyIntroduction.php
index 556e512070..c669800b51 100644
--- a/Neos.Flow/Classes/Aop/PropertyIntroduction.php
+++ b/Neos.Flow/Classes/Aop/PropertyIntroduction.php
@@ -21,7 +21,7 @@ class PropertyIntroduction
 {
     /**
      * Name of the aspect declaring this introduction
-     * @var string
+     * @var class-string
      */
     protected $declaringAspectClassName;
 
@@ -58,7 +58,7 @@ class PropertyIntroduction
     /**
      * Constructor
      *
-     * @param string $declaringAspectClassName Name of the aspect containing the declaration for this introduction
+     * @param class-string $declaringAspectClassName Name of the aspect containing the declaration for this introduction
      * @param string $propertyName Name of the property to introduce
      * @param Pointcut $pointcut The pointcut for this introduction
      */
@@ -80,7 +80,7 @@ public function __construct(string $declaringAspectClassName, string $propertyNa
         } else {
             $this->propertyVisibility = 'public';
         }
-        $this->propertyDocComment = preg_replace('/@(Neos\\\\Flow\\\\Annotations|Flow)\\\\Introduce.+$/mi', 'introduced by ' . $declaringAspectClassName, $propertyReflection->getDocComment());
+        $this->propertyDocComment = preg_replace('/@(Neos\\\\Flow\\\\Annotations|Flow)\\\\Introduce.+$/mi', 'introduced by ' . $declaringAspectClassName, $propertyReflection->getDocComment() ?: '') ?: '';
     }
 
     /**
@@ -132,9 +132,9 @@ public function getPointcut(): Pointcut
     }
 
     /**
-     * Returns the object name of the aspect which declared this introduction
+     * Returns the class name of the aspect which declared this introduction
      *
-     * @return string The aspect object name
+     * @return class-string The aspect class name
      */
     public function getDeclaringAspectClassName(): string
     {
diff --git a/Neos.Flow/Classes/Aop/TraitIntroduction.php b/Neos.Flow/Classes/Aop/TraitIntroduction.php
index b9adfd6c7b..9443fde57a 100644
--- a/Neos.Flow/Classes/Aop/TraitIntroduction.php
+++ b/Neos.Flow/Classes/Aop/TraitIntroduction.php
@@ -21,13 +21,13 @@ class TraitIntroduction
 {
     /**
      * Name of the aspect declaring this introduction
-     * @var string
+     * @var class-string
      */
     protected $declaringAspectClassName;
 
     /**
      * Name of the introduced trait
-     * @var string
+     * @var trait-string
      */
     protected $traitName;
 
@@ -41,8 +41,8 @@ class TraitIntroduction
     /**
      * Constructor
      *
-     * @param string $declaringAspectClassName Name of the aspect containing the declaration for this introduction
-     * @param string $traitName Name of the trait to introduce
+     * @param class-string $declaringAspectClassName Name of the aspect containing the declaration for this introduction
+     * @param trait-string $traitName Name of the trait to introduce
      * @param Pointcut $pointcut The pointcut for this introduction
      */
     public function __construct(string $declaringAspectClassName, string $traitName, Pointcut $pointcut)
@@ -55,7 +55,7 @@ public function __construct(string $declaringAspectClassName, string $traitName,
     /**
      * Returns the name of the introduced trait
      *
-     * @return string Name of the introduced trait
+     * @return trait-string Name of the introduced trait
      */
     public function getTraitName(): string
     {
@@ -75,7 +75,7 @@ public function getPointcut(): Pointcut
     /**
      * Returns the object name of the aspect which declared this introduction
      *
-     * @return string The aspect object name
+     * @return class-string The aspect object name
      */
     public function getDeclaringAspectClassName(): string
     {
diff --git a/Neos.Flow/Classes/Cache/AnnotationsCacheFlusher.php b/Neos.Flow/Classes/Cache/AnnotationsCacheFlusher.php
index 60616e3916..c143a6f841 100644
--- a/Neos.Flow/Classes/Cache/AnnotationsCacheFlusher.php
+++ b/Neos.Flow/Classes/Cache/AnnotationsCacheFlusher.php
@@ -54,15 +54,15 @@ final class AnnotationsCacheFlusher
     /**
      * Caches to flush for a given annotation
      *
-     * @var array in the format [<AnnotationClassName> => [<CacheName_1>, <CacheName_2>]]
+     * @var array<class-string,list<string>> in the format [<AnnotationClassName> => [<CacheName_1>, <CacheName_2>]]
      */
     private $annotationToCachesMap = [];
 
     /**
      * Register an annotation that should trigger a cache flush
      *
-     * @param string $annotationClassName fully qualified class name of the annotation
-     * @param string[] $cacheNames Cache names to flush if a class containing the given annotation is compiled (e.g. ["Flow_Mvc_Routing_Route", Flow_Mvc_Routing_Resolve"])
+     * @param class-string $annotationClassName fully qualified class name of the annotation
+     * @param list<string> $cacheNames Cache names to flush if a class containing the given annotation is compiled (e.g. ["Flow_Mvc_Routing_Route", Flow_Mvc_Routing_Resolve"])
      */
     public function registerAnnotation(string $annotationClassName, array $cacheNames): void
     {
@@ -72,7 +72,7 @@ public function registerAnnotation(string $annotationClassName, array $cacheName
     /**
      * A slot that flushes caches as needed if classes with specific annotations have changed @see registerAnnotation()
      *
-     * @param array<string> $classNames The full class names of the classes that got compiled
+     * @param array<class-string> $classNames The full class names of the classes that got compiled
      * @return void
      * @throws NoSuchCacheException
      */
diff --git a/Neos.Flow/Classes/Cache/CacheFactory.php b/Neos.Flow/Classes/Cache/CacheFactory.php
index 1b2f885775..3f7537c155 100644
--- a/Neos.Flow/Classes/Cache/CacheFactory.php
+++ b/Neos.Flow/Classes/Cache/CacheFactory.php
@@ -83,7 +83,7 @@ public function __construct(ApplicationContext $context, Environment $environmen
      * @param string $cacheIdentifier
      * @param string $cacheObjectName
      * @param string $backendObjectName
-     * @param array $backendOptions
+     * @param array<mixed> $backendOptions
      * @param bool $persistent
      * @return FrontendInterface
      */
@@ -112,7 +112,7 @@ protected function instantiateCache(string $cacheIdentifier, string $cacheObject
 
     /**
      * @param string $backendObjectName
-     * @param array $backendOptions
+     * @param array<string,mixed> $backendOptions
      * @param EnvironmentConfiguration $environmentConfiguration
      * @param boolean $persistent
      * @return BackendInterface
diff --git a/Neos.Flow/Classes/Cache/CacheManager.php b/Neos.Flow/Classes/Cache/CacheManager.php
index b4e6b4c6d6..78a1ccbf2c 100644
--- a/Neos.Flow/Classes/Cache/CacheManager.php
+++ b/Neos.Flow/Classes/Cache/CacheManager.php
@@ -11,6 +11,7 @@
  * source code.
  */
 
+use Neos\Cache\Backend\BackendInterface;
 use Neos\Cache\CacheFactoryInterface;
 use Neos\Flow\Annotations as Flow;
 use Neos\Cache\Backend\FileBackend;
@@ -32,6 +33,12 @@
 /**
  * The Cache Manager
  *
+ * @phpstan-type CacheConfiguration array{
+ *      frontend?: class-string<FrontendInterface>,
+ *      backend?: class-string<BackendInterface>,
+ *      backendOptions?: array<mixed>,
+ *      persistent?: bool,
+ * }
  * @Flow\Scope("singleton")
  * @api
  */
@@ -73,12 +80,12 @@ class CacheManager
     protected $cacheItemPools = [];
 
     /**
-     * @var array
+     * @var array<string,FrontendInterface>
      */
     protected $persistentCaches = [];
 
     /**
-     * @var array
+     * @var array<string,CacheConfiguration>
      */
     protected $cacheConfigurations = [
         'Default' => [
@@ -140,16 +147,13 @@ public function injectEnvironment(Environment $environment): void
      * If one of the options is not specified, the default value is assumed.
      * Existing cache configurations are preserved.
      *
-     * @param array $cacheConfigurations The cache configurations to set
+     * @todo enforce via extractor
+     * @param array<string,CacheConfiguration> $cacheConfigurations The cache configurations to set
      * @return void
-     * @throws \InvalidArgumentException
      */
     public function setCacheConfigurations(array $cacheConfigurations): void
     {
         foreach ($cacheConfigurations as $identifier => $configuration) {
-            if (!is_array($configuration)) {
-                throw new \InvalidArgumentException('The cache configuration for cache "' . $identifier . '" was not an array as expected.', 1231259656);
-            }
             $this->cacheConfigurations[$identifier] = $configuration;
         }
     }
@@ -301,7 +305,7 @@ public function flushCachesByTag(string $tag, bool $flushPersistentCaches = fals
     /**
      * Returns an array of cache configurations, indexed by cache identifier
      *
-     * @return array
+     * @return array<string,mixed>
      */
     public function getCacheConfigurations(): array
     {
@@ -320,7 +324,7 @@ public function getCacheConfigurations(): array
      *       time needed.
      *
      * @param string $fileMonitorIdentifier Identifier of the File Monitor
-     * @param array $changedFiles A list of full paths to changed files
+     * @param array<string,mixed> $changedFiles A list of full paths to changed files
      * @return void
      */
     public function flushSystemCachesByChangedFiles(string $fileMonitorIdentifier, array $changedFiles): void
@@ -341,7 +345,7 @@ public function flushSystemCachesByChangedFiles(string $fileMonitorIdentifier, a
     /**
      * Flushes entries tagged with class names if their class source files have changed.
      *
-     * @param array $changedFiles A list of full paths to changed files
+     * @param array<string,mixed> $changedFiles A list of full paths to changed files
      * @return void
      * @see flushSystemCachesByChangedFiles()
      */
@@ -355,7 +359,7 @@ protected function flushClassCachesByChangedFiles(array $changedFiles): void
             if (!file_exists($pathAndFilename)) {
                 continue;
             }
-            $fileContents = file_get_contents($pathAndFilename);
+            $fileContents = file_get_contents($pathAndFilename) ?: '';
             $className = (new PhpAnalyzer($fileContents))->extractFullyQualifiedClassName();
             if ($className === null) {
                 continue;
@@ -408,7 +412,7 @@ protected function flushClassCachesByChangedFiles(array $changedFiles): void
     /**
      * Flushes caches as needed if settings, routes or policies have changed
      *
-     * @param array $changedFiles A list of full paths to changed files
+     * @param array<string,mixed> $changedFiles A list of full paths to changed files
      * @return void
      * @see flushSystemCachesByChangedFiles()
      */
@@ -458,7 +462,7 @@ protected function flushConfigurationCachesByChangedFiles(array $changedFiles):
     /**
      * Flushes I18n caches if translation files have changed
      *
-     * @param array $changedFiles A list of full paths to changed files
+     * @param array<string, mixed> $changedFiles A list of full paths to changed files
      * @return void
      * @see flushSystemCachesByChangedFiles()
      */
@@ -495,11 +499,15 @@ protected function createAllCaches(): void
      */
     protected function createCache(string $identifier): void
     {
-        $frontend = isset($this->cacheConfigurations[$identifier]['frontend']) ? $this->cacheConfigurations[$identifier]['frontend'] : $this->cacheConfigurations['Default']['frontend'];
-        $backend = isset($this->cacheConfigurations[$identifier]['backend']) ? $this->cacheConfigurations[$identifier]['backend'] : $this->cacheConfigurations['Default']['backend'];
-        $backendOptions = isset($this->cacheConfigurations[$identifier]['backendOptions']) ? $this->cacheConfigurations[$identifier]['backendOptions'] : $this->cacheConfigurations['Default']['backendOptions'];
-        $persistent = isset($this->cacheConfigurations[$identifier]['persistent']) ? $this->cacheConfigurations[$identifier]['persistent'] : $this->cacheConfigurations['Default']['persistent'];
-        // @phpstan-ignore-next-line - $persistent is not yet part of the CacheFactoryInterface
+        /** @phpstan-ignore offsetAccess.notFound (always set for Default) */
+        $frontend = $this->cacheConfigurations[$identifier]['frontend'] ?? $this->cacheConfigurations['Default']['frontend'];
+        /** @phpstan-ignore offsetAccess.notFound (always set for Default) */
+        $backend = $this->cacheConfigurations[$identifier]['backend'] ?? $this->cacheConfigurations['Default']['backend'];
+        /** @phpstan-ignore offsetAccess.notFound (always set for Default) */
+        $backendOptions = $this->cacheConfigurations[$identifier]['backendOptions'] ?? $this->cacheConfigurations['Default']['backendOptions'];
+        /** @phpstan-ignore offsetAccess.notFound (always set for Default) */
+        $persistent = $this->cacheConfigurations[$identifier]['persistent'] ?? $this->cacheConfigurations['Default']['persistent'];
+        /** @phpstan-ignore arguments.count ($persistent is not part of the interface) */
         $cache = $this->cacheFactory->create($identifier, $frontend, $backend, $backendOptions, $persistent);
         $this->registerCache($cache, $persistent);
     }
diff --git a/Neos.Flow/Classes/Cli/Command.php b/Neos.Flow/Classes/Cli/Command.php
index 07f8e818ec..57f3727338 100644
--- a/Neos.Flow/Classes/Cli/Command.php
+++ b/Neos.Flow/Classes/Cli/Command.php
@@ -22,7 +22,7 @@
 class Command
 {
     /**
-     * @var string
+     * @var class-string<CommandControllerInterface>
      */
     protected $controllerClassName;
 
@@ -54,7 +54,7 @@ class Command
     /**
      * Constructor
      *
-     * @param string $controllerClassName Class name of the controller providing the command
+     * @param class-string<CommandControllerInterface> $controllerClassName Class name of the controller providing the command
      * @param string $controllerCommandName Command name, i.e. the method name of the command, without the "Command" suffix
      * @throws \InvalidArgumentException
      */
@@ -74,7 +74,7 @@ public function __construct(string $controllerClassName, string $controllerComma
     /**
      * @param ReflectionService $reflectionService Reflection service
      */
-    public function injectReflectionService(ReflectionService $reflectionService)
+    public function injectReflectionService(ReflectionService $reflectionService): void
     {
         $this->reflectionService = $reflectionService;
     }
@@ -82,13 +82,13 @@ public function injectReflectionService(ReflectionService $reflectionService)
     /**
      * @param ObjectManagerInterface $objectManager
      */
-    public function injectObjectManager(ObjectManagerInterface $objectManager)
+    public function injectObjectManager(ObjectManagerInterface $objectManager): void
     {
         $this->objectManager = $objectManager;
     }
 
     /**
-     * @return string
+     * @return class-string<CommandControllerInterface>
      */
     public function getControllerClassName(): string
     {
@@ -122,10 +122,16 @@ public function getShortDescription(): string
     {
         $commandMethodReflection = $this->getCommandMethodReflection();
         $lines = explode(chr(10), $commandMethodReflection->getDescription());
-        $shortDescription = ((count($lines) > 0) ? trim($lines[0]) : '<no description available>') . ($this->isDeprecated() ? ' <b>(DEPRECATED)</b>' : '');
+        /** @phpstan-ignore greater.alwaysTrue (not sure about this) */
+        $shortDescription = ((count($lines) > 0)
+            ? trim($lines[0])
+            : '<no description available>') . ($this->isDeprecated() ? ' <b>(DEPRECATED)</b>' : '');
 
         if ($commandMethodReflection->getDeclaringClass()->implementsInterface(DescriptionAwareCommandControllerInterface::class)) {
-            $shortDescription = call_user_func([$this->controllerClassName, 'processDescription'], $this->controllerCommandName, $shortDescription, $this->objectManager);
+            $callback = [$this->controllerClassName, 'processDescription'];
+            if (is_callable($callback)) {
+                $shortDescription = call_user_func($callback, $this->controllerCommandName, $shortDescription, $this->objectManager);
+            }
         }
         return $shortDescription;
     }
@@ -151,7 +157,10 @@ public function getDescription(): string
         }
         $description = implode(chr(10), $descriptionLines);
         if ($commandMethodReflection->getDeclaringClass()->implementsInterface(DescriptionAwareCommandControllerInterface::class)) {
-            $description = call_user_func([$this->controllerClassName, 'processDescription'], $this->controllerCommandName, $description, $this->objectManager);
+            $callback = [$this->controllerClassName, 'processDescription'];
+            if (is_callable($callback)) {
+                $description = call_user_func($callback, $this->controllerCommandName, $description, $this->objectManager);
+            }
         }
         return $description;
     }
@@ -239,7 +248,7 @@ public function isFlushingCaches(): bool
      * Returns an array of command identifiers which were specified in the "@see"
      * annotation of a command method.
      *
-     * @return array
+     * @return array<int,string>
      */
     public function getRelatedCommandIdentifiers(): array
     {
diff --git a/Neos.Flow/Classes/Cli/CommandArgumentDefinition.php b/Neos.Flow/Classes/Cli/CommandArgumentDefinition.php
index f912d6e34a..44495b5c65 100644
--- a/Neos.Flow/Classes/Cli/CommandArgumentDefinition.php
+++ b/Neos.Flow/Classes/Cli/CommandArgumentDefinition.php
@@ -62,7 +62,7 @@ public function getName(): string
     public function getDashedName(): string
     {
         $dashedName = ucfirst($this->name);
-        $dashedName = preg_replace('/([A-Z][a-z0-9]+)/', '$1-', $dashedName);
+        $dashedName = preg_replace('/([A-Z][a-z0-9]+)/', '$1-', $dashedName) ?: '';
         return '--' . strtolower(substr($dashedName, 0, -1));
     }
 
diff --git a/Neos.Flow/Classes/Cli/CommandController.php b/Neos.Flow/Classes/Cli/CommandController.php
index 39e590a53d..7a5a09dea9 100644
--- a/Neos.Flow/Classes/Cli/CommandController.php
+++ b/Neos.Flow/Classes/Cli/CommandController.php
@@ -12,10 +12,8 @@
  */
 
 use Neos\Flow\Annotations as Flow;
-use Neos\Flow\Command\HelpCommandController;
 use Neos\Flow\Mvc\Controller\Argument;
 use Neos\Flow\Mvc\Controller\Arguments;
-use Neos\Flow\Mvc\Exception\CommandException;
 use Neos\Flow\Mvc\Exception\InvalidArgumentTypeException;
 use Neos\Flow\Mvc\Exception\NoSuchCommandException;
 use Neos\Flow\Cli\Exception\StopCommandException;
@@ -189,10 +187,6 @@ protected function mapRequestArgumentsToControllerArguments()
                 $argumentValue = $this->output->ask(sprintf('<comment>Please specify the required argument "%s":</comment> ', $argumentName));
             }
 
-            if ($argumentValue === null) {
-                $exception = new CommandException(sprintf('Required argument "%s" is not set.', $argumentName), 1306755520);
-                $this->forward('error', HelpCommandController::class, ['exception' => $exception]);
-            }
             $argument->setValue($argumentValue);
         }
     }
@@ -204,8 +198,8 @@ protected function mapRequestArgumentsToControllerArguments()
      * without the need for a new request.
      *
      * @param string $commandName
-     * @param string $controllerObjectName
-     * @param array $arguments
+     * @param ?string $controllerObjectName
+     * @param array<mixed> $arguments
      * @return void
      * @throws StopCommandException
      */
@@ -213,7 +207,11 @@ protected function forward(string $commandName, ?string $controllerObjectName =
     {
         $this->request->setDispatched(false);
         $this->request->setControllerCommandName($commandName);
-        if ($controllerObjectName !== null) {
+        if (
+            $controllerObjectName !== null
+            && class_exists($controllerObjectName)
+            && is_subclass_of($controllerObjectName, CommandControllerInterface::class)
+        ) {
             $this->request->setControllerObjectName($controllerObjectName);
         }
         $this->request->setArguments($arguments);
@@ -284,7 +282,7 @@ public function getFlowInvocationString(): string
      * @see http://www.php.net/sprintf
      *
      * @param string $text Text to output
-     * @param array $arguments Optional arguments to use for sprintf
+     * @param array<mixed> $arguments Optional arguments to use for sprintf
      * @return void
      * @api
      */
@@ -297,7 +295,7 @@ protected function output(string $text, array $arguments = [])
      * Outputs specified text to the console window and appends a line break
      *
      * @param string $text Text to output
-     * @param array $arguments Optional arguments to use for sprintf
+     * @param array<mixed> $arguments Optional arguments to use for sprintf
      * @return void
      * @see output()
      * @see outputLines()
@@ -313,7 +311,7 @@ protected function outputLine(string $text = '', array $arguments = [])
      * console window
      *
      * @param string $text Text to output
-     * @param array $arguments Optional arguments to use for sprintf
+     * @param array<mixed> $arguments Optional arguments to use for sprintf
      * @param integer $leftPadding The number of spaces to use for indentation
      * @return void
      * @see outputLine()
diff --git a/Neos.Flow/Classes/Cli/CommandManager.php b/Neos.Flow/Classes/Cli/CommandManager.php
index bf28383652..b05606b2c3 100644
--- a/Neos.Flow/Classes/Cli/CommandManager.php
+++ b/Neos.Flow/Classes/Cli/CommandManager.php
@@ -27,22 +27,22 @@
 class CommandManager
 {
     /**
-     * @var array<Command>
+     * @var ?array<Command>
      */
     protected $availableCommands = null;
 
     /**
-     * @var array
+     * @var ?array<string,string>
      */
     protected $shortCommandIdentifiers = null;
 
     /**
-     * @var Bootstrap
+     * @var ?Bootstrap
      */
     protected $bootstrap;
 
     /**
-     * @var ObjectManagerInterface
+     * @var ?ObjectManagerInterface
      */
     protected $objectManager;
 
@@ -74,6 +74,9 @@ public function getAvailableCommands(): array
     {
         if ($this->availableCommands === null) {
             $this->availableCommands = [];
+            if ($this->objectManager === null) {
+                throw new \RuntimeException('missing object manager', 1744472974);
+            }
 
             foreach (static::getCommandControllerMethodArguments($this->objectManager) as $className => $methods) {
                 foreach (array_keys($methods) as $methodName) {
@@ -161,14 +164,13 @@ public function getShortestIdentifierForCommand(Command $command): string
     /**
      * Returns an array that contains all available command identifiers and their shortest non-ambiguous alias
      *
-     * @return array in the format array('full.command:identifier1' => 'alias1', 'full.command:identifier2' => 'alias2')
+     * @return array<string,string> in the format array('full.command:identifier1' => 'alias1', 'full.command:identifier2' => 'alias2')
      */
     protected function getShortCommandIdentifiers(): array
     {
         if ($this->shortCommandIdentifiers === null) {
             $this->shortCommandIdentifiers = [];
             $commandsByCommandName = [];
-            /** @var Command $availableCommand */
             foreach ($this->getAvailableCommands() as $availableCommand) {
                 list($packageKey, $controllerName, $commandName) = explode(':', $availableCommand->getCommandIdentifier());
                 if (!isset($commandsByCommandName[$commandName])) {
@@ -181,6 +183,9 @@ protected function getShortCommandIdentifiers(): array
             }
             foreach ($this->getAvailableCommands() as $availableCommand) {
                 list($packageKey, $controllerName, $commandName) = explode(':', $availableCommand->getCommandIdentifier());
+                if ($this->bootstrap === null) {
+                    throw new \RuntimeException('missing bootstrap', 1744472927);
+                }
                 if (count($commandsByCommandName[$commandName][$controllerName]) > 1 || $this->bootstrap->isCompiletimeCommand($availableCommand->getCommandIdentifier())) {
                     $packageKeyParts = array_reverse(explode('.', $packageKey));
                     for ($i = 1; $i <= count($packageKeyParts); $i++) {
@@ -245,18 +250,21 @@ protected function commandMatchesIdentifier(Command $command, string $commandIde
      *
      * @param string $controllerObjectName
      * @param string $commandMethodName
-     * @return array
+     * @return array<string,mixed>
      */
     public function getCommandMethodParameters(string $controllerObjectName, string $commandMethodName): array
     {
+        if ($this->objectManager === null) {
+            throw new \RuntimeException('missing object Manager', 1744472898);
+        }
         $commandControllerMethodArgumentMap = static::getCommandControllerMethodArguments($this->objectManager);
 
-        return isset($commandControllerMethodArgumentMap[$controllerObjectName][$commandMethodName]) ? $commandControllerMethodArgumentMap[$controllerObjectName][$commandMethodName] : [];
+        return $commandControllerMethodArgumentMap[$controllerObjectName][$commandMethodName] ?? [];
     }
 
     /**
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of method arguments per controller and method.
+     * @return array<class-string<CommandControllerInterface>,array<string, array<string,mixed>>> of method arguments per controller and method.
      * @Flow\CompileStatic
      */
     public static function getCommandControllerMethodArguments(ObjectManagerInterface $objectManager): array
@@ -269,12 +277,13 @@ public static function getCommandControllerMethodArguments(ObjectManagerInterfac
             if (!class_exists($className) || $reflectionService->isClassAbstract($className)) {
                 continue;
             }
-            /** @var string $controllerObjectName */
-            $controllerObjectName = $objectManager->getObjectNameByClassName($className);
-            $commandControllerMethodArgumentMap[$controllerObjectName] = [];
+            /** @todo what was this necessary for?
+             * $controllerObjectName = $objectManager->getObjectNameByClassName($className);
+             */
+            $commandControllerMethodArgumentMap[$className] = [];
             foreach (get_class_methods($className) as $methodName) {
                 if (str_ends_with($methodName, 'Command')) {
-                    $commandControllerMethodArgumentMap[$className][$methodName] = $reflectionService->getMethodParameters($controllerObjectName, $methodName);
+                    $commandControllerMethodArgumentMap[$className][$methodName] = $reflectionService->getMethodParameters($className, $methodName);
                 }
             }
         }
diff --git a/Neos.Flow/Classes/Cli/ConsoleOutput.php b/Neos.Flow/Classes/Cli/ConsoleOutput.php
index 9f3c792a07..a7c4ed341e 100644
--- a/Neos.Flow/Classes/Cli/ConsoleOutput.php
+++ b/Neos.Flow/Classes/Cli/ConsoleOutput.php
@@ -89,7 +89,7 @@ public function getMaximumLineLength(): int
      * @see http://www.php.net/sprintf
      *
      * @param string $text Text to output
-     * @param array $arguments Optional arguments to use for sprintf
+     * @param array<mixed> $arguments Optional arguments to use for sprintf
      * @return void
      */
     public function output(string $text, array $arguments = []): void
@@ -104,7 +104,7 @@ public function output(string $text, array $arguments = []): void
      * Outputs specified text to the console window and appends a line break
      *
      * @param string $text Text to output
-     * @param array $arguments Optional arguments to use for sprintf
+     * @param array<mixed> $arguments Optional arguments to use for sprintf
      * @return void
      * @see output()
      * @see outputLines()
@@ -119,7 +119,7 @@ public function outputLine(string $text = '', array $arguments = []): void
      * console window
      *
      * @param string $text Text to output
-     * @param array $arguments Optional arguments to use for sprintf
+     * @param array<mixed> $arguments Optional arguments to use for sprintf
      * @param integer $leftPadding The number of spaces to use for indentation
      * @return void
      * @see outputLine()
@@ -136,9 +136,9 @@ public function outputFormatted(string $text = '', array $arguments = [], int $l
     /**
      * Renders a table like output of the given $rows
      *
-     * @param array $rows
-     * @param array $headers
-     * @param string $headerTitle
+     * @param array<mixed> $rows
+     * @param ?array<mixed> $headers
+     * @param ?string $headerTitle
      */
     public function outputTable(array $rows, ?array $headers = null, ?string $headerTitle = null): void
     {
@@ -156,12 +156,12 @@ public function outputTable(array $rows, ?array $headers = null, ?string $header
     /**
      * Asks the user to select a value
      *
-     * @param string|array $question The question to ask. If an array each array item is turned into one line of a multi-line question
-     * @param array $choices List of choices to pick from
+     * @param string|array<string> $question The question to ask. If an array each array item is turned into one line of a multi-line question
+     * @param array<string> $choices List of choices to pick from
      * @param string|bool|int|float|null $default The default answer if the user enters nothing
      * @param boolean $multiSelect If true the result will be an array with the selected options. Multiple options can be given separated by commas
      * @param integer|null $attempts Max number of times to ask before giving up (null by default, which means infinite)
-     * @return integer|string|array Either the value for indexed arrays, the key for associative arrays or an array for multiple selections
+     * @return integer|string|array<mixed> Either the value for indexed arrays, the key for associative arrays or an array for multiple selections
      * @throws \InvalidArgumentException
      */
     public function select($question, array $choices, $default = null, bool $multiSelect = false, ?int $attempts = null)
@@ -178,8 +178,8 @@ public function select($question, array $choices, $default = null, bool $multiSe
     /**
      * Asks a question to the user
      *
-     * @param string|array $question The question to ask. If an array each array item is turned into one line of a multi-line question
-     * @param string $default The default answer if none is given by the user
+     * @param string|array<string> $question The question to ask. If an array each array item is turned into one line of a multi-line question
+     * @param ?string $default The default answer if none is given by the user
      * @return mixed The user answer
      * @throws \RuntimeException If there is no data to read in the input stream
      */
@@ -207,7 +207,7 @@ public function askQuestion(Question $question)
      *
      * The question will be asked until the user answers by nothing, yes, or no.
      *
-     * @param string|array $question The question to ask. If an array each array item is turned into one line of a multi-line question
+     * @param string|array<string> $question The question to ask. If an array each array item is turned into one line of a multi-line question
      * @param boolean $default The default answer if the user enters nothing
      * @return boolean true if the user has confirmed, false otherwise
      */
@@ -221,7 +221,7 @@ public function askConfirmation($question, bool $default = true): bool
     /**
      * Asks a question to the user, the response is hidden
      *
-     * @param string|array $question The question. If an array each array item is turned into one line of a multi-line question
+     * @param string|array<string> $question The question. If an array each array item is turned into one line of a multi-line question
      * @param Boolean $fallback In case the response can not be hidden, whether to fallback on non-hidden question or not
      * @return mixed The answer
      * @throws \RuntimeException In case the fallback is deactivated and the response can not be hidden
@@ -244,7 +244,7 @@ public function askHiddenResponse($question, bool $fallback = true)
      * otherwise.
      *
      * @see https://symfony.com/doc/current/components/console/helpers/questionhelper.html#validating-the-answer
-     * @param string|array $question The question to ask. If an array each array item is turned into one line of a multi-line question
+     * @param string|array<string> $question The question to ask. If an array each array item is turned into one line of a multi-line question
      * @param callable $validator A PHP callback that gets a value and is expected to return the (transformed) value or throw an exception if it wasn't valid
      * @param integer|null $attempts Max number of times to ask before giving up (null by default, which means infinite)
      * @param string $default The default answer if none is given by the user
@@ -268,7 +268,7 @@ public function askAndValidate($question, callable $validator, ?int $attempts =
      * validated data when the data is valid and throw an exception
      * otherwise.
      *
-     * @param string|array $question The question to ask. If an array each array item is turned into one line of a multi-line question
+     * @param string|array<string> $question The question to ask. If an array each array item is turned into one line of a multi-line question
      * @param callable $validator A PHP callback that gets a value and is expected to return the (transformed) value or throw an exception if it wasn't valid
      * @param integer|null $attempts Max number of times to ask before giving up (null by default, which means infinite)
      * @param boolean $fallback In case the response can not be hidden, whether to fallback on non-hidden question or not
@@ -384,7 +384,7 @@ public function getQuestionHelper(): QuestionHelper
     /**
      * If question is an array, split it into multi-line string
      *
-     * @param string|array $question
+     * @param string|array<mixed> $question
      * @return string
      */
     protected function combineQuestion($question): string
@@ -405,12 +405,8 @@ public function getProgressBar(): ProgressBar
     {
         if ($this->progressBar === null) {
             $this->progressBar = new ProgressBar($this->output);
-            if (is_callable([$this->progressBar, 'minSecondsBetweenRedraws'])) {
-                $this->progressBar->minSecondsBetweenRedraws(0);
-            }
-            if (is_callable([$this->progressBar, 'maxSecondsBetweenRedraws'])) {
-                $this->progressBar->maxSecondsBetweenRedraws(0);
-            }
+            $this->progressBar->minSecondsBetweenRedraws(0);
+            $this->progressBar->maxSecondsBetweenRedraws(0);
         }
         return $this->progressBar;
     }
diff --git a/Neos.Flow/Classes/Cli/Dispatcher.php b/Neos.Flow/Classes/Cli/Dispatcher.php
index 9b123c6b31..90d219aa01 100644
--- a/Neos.Flow/Classes/Cli/Dispatcher.php
+++ b/Neos.Flow/Classes/Cli/Dispatcher.php
@@ -27,7 +27,7 @@ class Dispatcher
     /**
      * @param \Neos\Flow\SignalSlot\Dispatcher $signalDispatcher
      */
-    public function injectSignalDispatcher(\Neos\Flow\SignalSlot\Dispatcher $signalDispatcher)
+    public function injectSignalDispatcher(\Neos\Flow\SignalSlot\Dispatcher $signalDispatcher): void
     {
         $this->signalDispatcher = $signalDispatcher;
     }
@@ -35,7 +35,7 @@ public function injectSignalDispatcher(\Neos\Flow\SignalSlot\Dispatcher $signalD
     /**
      * @param ObjectManagerInterface $objectManager
      */
-    public function injectObjectManager(ObjectManagerInterface $objectManager)
+    public function injectObjectManager(ObjectManagerInterface $objectManager): void
     {
         $this->objectManager = $objectManager;
     }
@@ -108,16 +108,11 @@ protected function emitAfterControllerInvocation(Request $request, Response $res
     protected function resolveController(Request $request): CommandControllerInterface
     {
         $controllerObjectName = $request->getControllerObjectName();
-        if ($controllerObjectName === '') {
+        if ($controllerObjectName === null) {
             $exceptionMessage = 'No controller could be resolved which would match your request';
             throw new InvalidCommandControllerException($exceptionMessage, 1565878092);
         }
 
-        $controller = $this->objectManager->get($controllerObjectName);
-        if (!$controller instanceof CommandControllerInterface) {
-            throw new InvalidCommandControllerException('Invalid controller "' . $request->getControllerObjectName() . '". The controller must be a valid request handling controller, ' . (is_object($controller) ? get_class($controller) : gettype($controller)) . ' given.', 1565878098);
-        }
-
-        return $controller;
+        return $this->objectManager->get($controllerObjectName);
     }
 }
diff --git a/Neos.Flow/Classes/Cli/Request.php b/Neos.Flow/Classes/Cli/Request.php
index dcbfb5e4af..e9c26e5b52 100644
--- a/Neos.Flow/Classes/Cli/Request.php
+++ b/Neos.Flow/Classes/Cli/Request.php
@@ -22,7 +22,7 @@
 class Request
 {
     /**
-     * @var string
+     * @var ?class-string<CommandControllerInterface>
      */
     protected $controllerObjectName;
 
@@ -38,12 +38,12 @@ class Request
 
     /**
      * The arguments for this request
-     * @var array
+     * @var array<string,mixed>
      */
     protected $arguments = [];
 
     /**
-     * @var array
+     * @var array<int,mixed>
      */
     protected $exceedingArguments = [];
 
@@ -81,7 +81,7 @@ public function isDispatched(): bool
     /**
      * Sets the object name of the controller
      *
-     * @param string $controllerObjectName Object name of the controller which processes this request
+     * @param class-string<CommandControllerInterface> $controllerObjectName Object name of the controller which processes this request
      * @return void
      */
     public function setControllerObjectName(string $controllerObjectName)
@@ -93,9 +93,9 @@ public function setControllerObjectName(string $controllerObjectName)
     /**
      * Returns the object name of the controller
      *
-     * @return string The controller's object name
+     * @return ?class-string<CommandControllerInterface> The controller's object name
      */
-    public function getControllerObjectName(): string
+    public function getControllerObjectName(): ?string
     {
         return $this->controllerObjectName;
     }
@@ -132,6 +132,9 @@ public function getControllerCommandName(): string
     public function getCommand(): Command
     {
         if ($this->command === null) {
+            if ($this->controllerObjectName === null) {
+                throw new \RuntimeException('missing controller object name', 1744472740);
+            }
             $this->command = new Command($this->controllerObjectName, $this->controllerCommandName);
         }
         return $this->command;
@@ -156,7 +159,7 @@ public function setArgument(string $argumentName, $value): void
     /**
      * Sets the whole arguments array and therefore replaces any arguments which existed before.
      *
-     * @param array $arguments An array of argument names and their values
+     * @param array<string,mixed> $arguments An array of argument names and their values
      * @return void
      */
     public function setArguments(array $arguments)
@@ -193,7 +196,7 @@ public function hasArgument(string $argumentName): bool
     /**
      * Returns an ArrayObject of arguments and their values
      *
-     * @return array Array of arguments and their values (which may be arguments and values as well)
+     * @return array<string,mixed> Array of arguments and their values (which may be arguments and values as well)
      */
     public function getArguments(): array
     {
@@ -203,7 +206,7 @@ public function getArguments(): array
     /**
      * Sets the exceeding arguments
      *
-     * @param array $exceedingArguments Numeric array of exceeding arguments
+     * @param array<int,mixed> $exceedingArguments Numeric array of exceeding arguments
      * @return void
      */
     public function setExceedingArguments(array $exceedingArguments)
@@ -219,7 +222,7 @@ public function setExceedingArguments(array $exceedingArguments)
      * ./flow acme:foo --argument1 Foo --argument2 Bar baz quux
      * this method would return array(0 => 'baz', 1 => 'quux')
      *
-     * @return array Numeric array of exceeding argument values
+     * @return array<int, mixed> Numeric array of exceeding argument values
      */
     public function getExceedingArguments(): array
     {
diff --git a/Neos.Flow/Classes/Cli/RequestBuilder.php b/Neos.Flow/Classes/Cli/RequestBuilder.php
index df1ee24411..cdc4749817 100644
--- a/Neos.Flow/Classes/Cli/RequestBuilder.php
+++ b/Neos.Flow/Classes/Cli/RequestBuilder.php
@@ -163,13 +163,14 @@ public function build($commandLine): Request
 
             return $request;
         }
-        /** @var string $controllerObjectName */
-        $controllerObjectName = $this->objectManager->getObjectNameByClassName($command->getControllerClassName());
+        /** @todo what was this necessary for?
+         *$controllerObjectName = $this->objectManager->getObjectNameByClassName($command->getControllerClassName());
+         */
         $controllerCommandName = $command->getControllerCommandName();
-        $request->setControllerObjectName($controllerObjectName);
+        $request->setControllerObjectName($command->getControllerClassName());
         $request->setControllerCommandName($controllerCommandName);
 
-        list($commandLineArguments, $exceedingCommandLineArguments) = $this->parseRawCommandLineArguments($rawCommandLineArguments, $controllerObjectName, $controllerCommandName);
+        list($commandLineArguments, $exceedingCommandLineArguments) = $this->parseRawCommandLineArguments($rawCommandLineArguments, $command->getControllerClassName(), $controllerCommandName);
         $request->setArguments($commandLineArguments);
         $request->setExceedingArguments($exceedingCommandLineArguments);
 
@@ -180,10 +181,10 @@ public function build($commandLine): Request
      * Takes an array of unparsed command line arguments and options and converts it separated
      * by named arguments, options and unnamed arguments.
      *
-     * @param array $rawCommandLineArguments The unparsed command parts (such as "--foo") as an array
+     * @param array<mixed> $rawCommandLineArguments The unparsed command parts (such as "--foo") as an array
      * @param string $controllerObjectName Object name of the designated command controller
      * @param string $controllerCommandName Command name of the recognized command (ie. method name without "Command" suffix)
-     * @return array All and exceeding command line arguments
+     * @return array{0: array<string,mixed>, 1: array<int,mixed>} All and exceeding command line arguments
      * @throws InvalidArgumentMixingException
      */
     protected function parseRawCommandLineArguments(array $rawCommandLineArguments, string $controllerObjectName, string $controllerCommandName): array
@@ -281,7 +282,7 @@ protected function extractArgumentNameFromCommandLinePart(string $commandLinePar
      * Returns the value of the first argument of the given input array. Shifts the parsed argument off the array.
      *
      * @param string $currentArgument The current argument
-     * @param array &$rawCommandLineArguments Array of the remaining command line arguments
+     * @param array<mixed> &$rawCommandLineArguments Array of the remaining command line arguments
      * @param string $expectedArgumentType The expected type of the current argument, because booleans get special attention
      * @return mixed The value of the first argument
      */
diff --git a/Neos.Flow/Classes/Cli/Response.php b/Neos.Flow/Classes/Cli/Response.php
index 196653d923..042a1827bd 100644
--- a/Neos.Flow/Classes/Cli/Response.php
+++ b/Neos.Flow/Classes/Cli/Response.php
@@ -61,7 +61,6 @@ class Response
      *
      * @param integer $exitCode
      * @return void
-     * @throws \InvalidArgumentException
      * @api
      */
     public function setExitCode(int $exitCode): void
@@ -190,21 +189,21 @@ public function send(): void
 
         $content = $this->getContent();
         if ($this->hasColorSupport() === true) {
-            $content =  preg_replace('|\<b>(((?!\</b>).)*)\</b>|', "\x1B[" . self::STYLE_BRIGHT . "m\$1\x1B[0m", $content);
-            $content =  preg_replace('|\<i>(((?!\</i>).)*)\</i>|', "\x1B[" . self::STYLE_ITALIC . "m\$1\x1B[0m", $content);
-            $content =  preg_replace('|\<u>(((?!\</u>).)*)\</u>|', "\x1B[" . self::STYLE_UNDERLINED . "m\$1\x1B[0m", $content);
-            $content =  preg_replace('|\<em>(((?!\</em>).)*)\</em>|', "\x1B[" . self::STYLE_INVERSE . "m\$1\x1B[0m", $content);
-            $content =  preg_replace('|\<strike>(((?!\</strike>).)*)\</strike>|', "\x1B[" . self::STYLE_STRIKETHROUGH . "m\$1\x1B[0m", $content);
-            $content =  preg_replace('|\<error>(((?!\</error>).)*)\</error>|', "\x1B[" . self::STYLE_ERROR . "m\$1\x1B[0m", $content);
-            $content =  preg_replace('|\<success>(((?!\</success>).)*)\</success>|', "\x1B[" . self::STYLE_SUCCESS . "m\$1\x1B[0m", $content);
+            $content =  preg_replace('|\<b>(((?!\</b>).)*)\</b>|', "\x1B[" . self::STYLE_BRIGHT . "m\$1\x1B[0m", $content) ?: '';
+            $content =  preg_replace('|\<i>(((?!\</i>).)*)\</i>|', "\x1B[" . self::STYLE_ITALIC . "m\$1\x1B[0m", $content) ?: '';
+            $content =  preg_replace('|\<u>(((?!\</u>).)*)\</u>|', "\x1B[" . self::STYLE_UNDERLINED . "m\$1\x1B[0m", $content) ?: '';
+            $content =  preg_replace('|\<em>(((?!\</em>).)*)\</em>|', "\x1B[" . self::STYLE_INVERSE . "m\$1\x1B[0m", $content) ?: '';
+            $content =  preg_replace('|\<strike>(((?!\</strike>).)*)\</strike>|', "\x1B[" . self::STYLE_STRIKETHROUGH . "m\$1\x1B[0m", $content) ?: '';
+            $content =  preg_replace('|\<error>(((?!\</error>).)*)\</error>|', "\x1B[" . self::STYLE_ERROR . "m\$1\x1B[0m", $content) ?: '';
+            $content =  preg_replace('|\<success>(((?!\</success>).)*)\</success>|', "\x1B[" . self::STYLE_SUCCESS . "m\$1\x1B[0m", $content) ?: '';
         } else {
-            $content =  preg_replace('|\<b>(((?!\</b>).)*)\</b>|', "$1", $content);
-            $content =  preg_replace('|\<i>(((?!\</i>).)*)\</i>|', "$1", $content);
-            $content =  preg_replace('|\<u>(((?!\</u>).)*)\</u>|', "$1", $content);
-            $content =  preg_replace('|\<em>(((?!\</em>).)*)\</em>|', "$1", $content);
-            $content =  preg_replace('|\<strike>(((?!\</strike>).)*)\</strike>|', "$1", $content);
-            $content =  preg_replace('|\<error>(((?!\</strike>).)*)\</error>|', "$1", $content);
-            $content =  preg_replace('|\<success>(((?!\</strike>).)*)\</success>|', "$1", $content);
+            $content =  preg_replace('|\<b>(((?!\</b>).)*)\</b>|', "$1", $content) ?: '';
+            $content =  preg_replace('|\<i>(((?!\</i>).)*)\</i>|', "$1", $content) ?: '';
+            $content =  preg_replace('|\<u>(((?!\</u>).)*)\</u>|', "$1", $content) ?: '';
+            $content =  preg_replace('|\<em>(((?!\</em>).)*)\</em>|', "$1", $content) ?: '';
+            $content =  preg_replace('|\<strike>(((?!\</strike>).)*)\</strike>|', "$1", $content) ?: '';
+            $content =  preg_replace('|\<error>(((?!\</strike>).)*)\</error>|', "$1", $content) ?: '';
+            $content =  preg_replace('|\<success>(((?!\</strike>).)*)\</success>|', "$1", $content) ?: '';
         }
         echo $content;
     }
diff --git a/Neos.Flow/Classes/Cli/SlaveRequestHandler.php b/Neos.Flow/Classes/Cli/SlaveRequestHandler.php
index 794e96bf48..e8540bd22e 100644
--- a/Neos.Flow/Classes/Cli/SlaveRequestHandler.php
+++ b/Neos.Flow/Classes/Cli/SlaveRequestHandler.php
@@ -88,7 +88,7 @@ public function handleRequest()
         try {
             $response = null;
             while (true) {
-                $commandLine = trim(fgets(STDIN));
+                $commandLine = trim(fgets(STDIN) ?: '');
                 $trimmedCommandLine = trim($commandLine);
                 $logger->info(sprintf('Received command "%s".', $trimmedCommandLine), LogEnvironment::fromMethodName(__METHOD__));
                 if ($commandLine === "QUIT\n") {
diff --git a/Neos.Flow/Classes/Command/CacheCommandController.php b/Neos.Flow/Classes/Command/CacheCommandController.php
index 414e3724ec..ab9b263535 100644
--- a/Neos.Flow/Classes/Command/CacheCommandController.php
+++ b/Neos.Flow/Classes/Command/CacheCommandController.php
@@ -271,7 +271,6 @@ public function listCommand(bool $quiet = false)
             $this->outputLine('<error>The following caches contain errors or warnings: %s</error>', [implode(', ', $erroneousCaches)]);
             $quiet || $this->outputLine('Use the <em>neos.flow:cache:show</em> Command for more information');
             $this->quit(1);
-            return;
         }
     }
 
@@ -291,7 +290,6 @@ public function showCommand(string $cacheIdentifier)
             $this->outputLine('<error>A Cache with id "%s" is not configured.</error>', [$cacheIdentifier]);
             $this->outputLine('Use the <i>neos.flow:cache:list</i> command to get a list of all configured Caches.');
             $this->quit(1);
-            return;
         }
         $cacheConfigurations = $this->cacheManager->getCacheConfigurations();
         $defaultConfiguration = $cacheConfigurations['Default'];
@@ -302,7 +300,7 @@ public function showCommand(string $cacheIdentifier)
         $this->outputLine('<b>Backend</b>: %s', [TypeHandling::getTypeForValue($cacheBackend)]);
         $options = $cacheConfiguration['backendOptions'] ?? $defaultConfiguration['backendOptions'];
         $this->outputLine('<b>Backend Options</b>:');
-        $this->outputLine(json_encode($options, JSON_PRETTY_PRINT));
+        $this->outputLine(json_encode($options, JSON_PRETTY_PRINT | JSON_THROW_ON_ERROR));
 
         if ($cacheBackend instanceof WithStatusInterface) {
             $this->outputLine();
@@ -313,7 +311,6 @@ public function showCommand(string $cacheIdentifier)
 
             if ($cacheStatus->hasErrors() || $cacheStatus->hasWarnings()) {
                 $this->quit(1);
-                return;
             }
         }
     }
@@ -338,20 +335,17 @@ public function setupCommand(string $cacheIdentifier)
             $this->outputLine('<error>A Cache with id "%s" is not configured.</error>', [$cacheIdentifier]);
             $this->outputLine('Use the <i>neos.flow:cache:list</i> command to get a list of all configured Caches.');
             $this->quit(1);
-            return;
         }
         $cacheBackend = $cache->getBackend();
         if (!$cacheBackend instanceof WithSetupInterface) {
             $this->outputLine('<error>The Cache "%s" is configured to use the backend "%s" but this does not implement the WithSetupInterface.</error>', [$cacheIdentifier, TypeHandling::getTypeForValue($cacheBackend)]);
             $this->quit(1);
-            return;
         }
         $this->outputLine('Setting up backend <b>%s</b> for cache "%s"', [TypeHandling::getTypeForValue($cacheBackend), $cache->getIdentifier()]);
         $setupResult = $cacheBackend->setup();
         $this->renderResult($setupResult);
         if ($setupResult->hasErrors() || $setupResult->hasWarnings()) {
             $this->quit(1);
-            return;
         }
     }
 
@@ -390,7 +384,6 @@ public function setupAllCommand(bool $quiet = false)
         }
         if ($hasErrorsOrWarnings) {
             $this->quit(1);
-            return;
         }
     }
 
diff --git a/Neos.Flow/Classes/Command/ConfigurationCommandController.php b/Neos.Flow/Classes/Command/ConfigurationCommandController.php
index 742642ee16..1f0404da13 100644
--- a/Neos.Flow/Classes/Command/ConfigurationCommandController.php
+++ b/Neos.Flow/Classes/Command/ConfigurationCommandController.php
@@ -75,7 +75,7 @@ public function showCommand(string $type = 'Settings', string $path = '', int $d
             }
             $configuration = self::truncateArrayAtDepth($configuration, $depth);
             $typeAndPath = $type . ($path ? ': ' . $path : '');
-            if ($configuration === null) {
+            if ($configuration === []) {
                 $this->outputLine('<b>Configuration "%s" was empty!</b>', [$typeAndPath]);
             } else {
                 $yaml = Yaml::dump($configuration, 99);
@@ -96,8 +96,10 @@ public function showCommand(string $type = 'Settings', string $path = '', int $d
     }
 
     /**
+     * @param array<mixed> $array
      * @param int $maximumDepth 0 for no truncation and 1 to only show the first keys of the array
      * @param int $currentLevel 1 for the start and will be incremented recursively
+     * @return array<mixed>
      */
     private static function truncateArrayAtDepth(array $array, int $maximumDepth, int $currentLevel = 1): array
     {
@@ -167,7 +169,6 @@ public function validateCommand(?string $type = null, ?string $path = null, bool
             $this->outputLine('<b>Exception:</b>');
             $this->outputFormatted($exception->getMessage(), [], 4);
             $this->quit(2);
-            return;
         }
 
         if ($verbose) {
diff --git a/Neos.Flow/Classes/Command/CoreCommandController.php b/Neos.Flow/Classes/Command/CoreCommandController.php
index 4e1607e0e8..60d8df9554 100644
--- a/Neos.Flow/Classes/Command/CoreCommandController.php
+++ b/Neos.Flow/Classes/Command/CoreCommandController.php
@@ -74,7 +74,7 @@ class CoreCommandController extends CommandController
     protected $aopProxyClassBuilder;
 
     /**
-     * @var ProxyClassBuilder
+     * @var ProxyClassBuilder<object>
      */
     protected $dependencyInjectionProxyClassBuilder;
 
@@ -147,7 +147,7 @@ public function injectAopProxyClassBuilder(AopProxyClassBuilder $aopProxyClassBu
     }
 
     /**
-     * @param ProxyClassBuilder $dependencyInjectionProxyClassBuilder
+     * @param ProxyClassBuilder<object> $dependencyInjectionProxyClassBuilder
      * @return void
      */
     public function injectDependencyInjectionProxyClassBuilder(ProxyClassBuilder $dependencyInjectionProxyClassBuilder)
diff --git a/Neos.Flow/Classes/Command/DatabaseCommandController.php b/Neos.Flow/Classes/Command/DatabaseCommandController.php
index 2700942e32..2e06f10971 100644
--- a/Neos.Flow/Classes/Command/DatabaseCommandController.php
+++ b/Neos.Flow/Classes/Command/DatabaseCommandController.php
@@ -28,7 +28,7 @@ class DatabaseCommandController extends CommandController
 {
     /**
      * @Flow\InjectConfiguration(path="persistence")
-     * @var array
+     * @var array<mixed>
      */
     protected $persistenceSettings = [];
 
@@ -86,7 +86,7 @@ protected function initializeConnection()
      * @throws DBALException
      * @throws StopActionException
      */
-    public function setCharsetCommand(string $characterSet = 'utf8mb4', string $collation = 'utf8mb4_unicode_ci', ?string $output = null, bool $verbose = false)
+    public function setCharsetCommand(string $characterSet = 'utf8mb4', string $collation = 'utf8mb4_unicode_ci', ?string $output = null, bool $verbose = false): void
     {
         if (!in_array($this->persistenceSettings['backendOptions']['driver'], ['pdo_mysql', 'mysqli'])) {
             $this->outputLine('Database charset/collation fixing is only supported on MySQL.');
@@ -118,13 +118,13 @@ public function setCharsetCommand(string $characterSet = 'utf8mb4', string $coll
      * @throws ConnectionException
      * @throws DBALException
      */
-    protected function convertToCharacterSetAndCollation(string $characterSet, string $collation, ?string $outputPathAndFilename = null, bool $verbose = false)
+    protected function convertToCharacterSetAndCollation(string $characterSet, string $collation, ?string $outputPathAndFilename = null, bool $verbose = false): void
     {
         $statements = ['SET foreign_key_checks = 0'];
 
         $statements[] = 'ALTER DATABASE ' . $this->connection->quoteIdentifier($this->persistenceSettings['backendOptions']['dbname']) . ' CHARACTER SET ' . $characterSet . ' COLLATE ' . $collation;
 
-        $tableNames = $this->connection->createSchemaManager()->listTableNames() ?? [];
+        $tableNames = $this->connection->createSchemaManager()->listTableNames();
         foreach ($tableNames as $tableName) {
             $statements[] = 'ALTER TABLE ' . $this->connection->quoteIdentifier($tableName) . ' DEFAULT CHARACTER SET ' . $characterSet . ' COLLATE ' . $collation;
             $statements[] = 'ALTER TABLE ' . $this->connection->quoteIdentifier($tableName) . ' CONVERT TO CHARACTER SET ' . $characterSet . ' COLLATE ' . $collation;
diff --git a/Neos.Flow/Classes/Command/DoctrineCommandController.php b/Neos.Flow/Classes/Command/DoctrineCommandController.php
index 66963e7e53..45a7eb7e2b 100644
--- a/Neos.Flow/Classes/Command/DoctrineCommandController.php
+++ b/Neos.Flow/Classes/Command/DoctrineCommandController.php
@@ -39,7 +39,7 @@
 class DoctrineCommandController extends CommandController
 {
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $settings = [];
 
@@ -70,7 +70,7 @@ class DoctrineCommandController extends CommandController
     /**
      * Injects the Flow settings, only the persistence part is kept for further use
      *
-     * @param array $settings
+     * @param array<mixed> $settings
      * @return void
      */
     public function injectSettings(array $settings): void
@@ -510,9 +510,8 @@ public function migrationGenerateCommand(bool $diffAgainstCurrent = true, ?strin
 
             $migrationPlatformFolderPart = $migrationFolder ?? $this->doctrineService->getMigrationFolderName();
 
-            if ($selectedPackage !== $choices[0]) {
+            if (is_string($selectedPackage) && $selectedPackage !== $choices[0]) {
                 $selectedPackage = $packages[$selectedPackage];
-                /** @var Package $selectedPackage */
                 $targetPathAndFilename = Files::concatenatePaths([$selectedPackage->getPackagePath(), 'Migrations', $migrationPlatformFolderPart, basename($migrationClassPathAndFilename)]);
                 Files::createDirectoryRecursively(dirname($targetPathAndFilename));
                 rename($migrationClassPathAndFilename, $targetPathAndFilename);
@@ -569,7 +568,7 @@ private function normalizeVersion(string $version): string
         return sprintf('Neos\Flow\Persistence\Doctrine\Migrations\Version%s', $version);
     }
 
-    private function maybeOutputMigrationFolderWarning(?string $migrationFolder = null)
+    private function maybeOutputMigrationFolderWarning(?string $migrationFolder = null): void
     {
         if ($migrationFolder !== null) {
             $this->outputLine('<comment>Migration folder override is in effect, migration files are not searched in folder matching the configured connection but in ...Migrations/%s/</comment>', [$migrationFolder]);
diff --git a/Neos.Flow/Classes/Command/HelpCommandController.php b/Neos.Flow/Classes/Command/HelpCommandController.php
index 3f44acb8c5..bcf34ee1c5 100644
--- a/Neos.Flow/Classes/Command/HelpCommandController.php
+++ b/Neos.Flow/Classes/Command/HelpCommandController.php
@@ -15,6 +15,7 @@
 use Neos\Flow\Cli\Command;
 use Neos\Flow\Cli\CommandArgumentDefinition;
 use Neos\Flow\Cli\CommandController;
+use Neos\Flow\Cli\CommandControllerInterface;
 use Neos\Flow\Core\Bootstrap;
 use Neos\Flow\Mvc\Exception\AmbiguousCommandIdentifierException;
 use Neos\Flow\Mvc\Exception\CommandException;
@@ -176,7 +177,7 @@ protected function displayHelpForCommand(Command $command)
             if (!$commandArgumentDefinition->isRequired()) {
                 $hasOptions = true;
             } else {
-                $usage .= sprintf(' <%s>', strtolower(preg_replace('/([A-Z])/', ' $1', $commandArgumentDefinition->getName())));
+                $usage .= sprintf(' <%s>', strtolower(preg_replace('/([A-Z])/', ' $1', $commandArgumentDefinition->getName()) ?: ''));
             }
         }
 
@@ -270,18 +271,17 @@ public function errorCommand(CommandException $exception)
      * added to the commands array of this class.
      *
      * @param array<Command> $commands
-     * @return array in the format array('<packageKey>' => array('<CommandControllerClassName>', array('<command1>' => $command1, '<command2>' => $command2)))
+     * @return array<string,array<class-string<CommandControllerInterface>,array<string,Command>>> in the format array('<packageKey>' => array('<CommandControllerClassName>', array('<command1>' => $command1, '<command2>' => $command2)))
      */
     protected function buildCommandsIndex(array $commands)
     {
         $commandsByPackagesAndControllers = [];
-        /** @var Command $command */
         foreach ($commands as $command) {
             if ($command->isInternal()) {
                 continue;
             }
             $commandIdentifier = $command->getCommandIdentifier();
-            $packageKey = strstr($commandIdentifier, ':', true);
+            $packageKey = (string)strstr($commandIdentifier, ':', true);
             $commandControllerClassName = $command->getControllerClassName();
             $commandName = $command->getControllerCommandName();
             $commandsByPackagesAndControllers[$packageKey][$commandControllerClassName][$commandName] = $command;
diff --git a/Neos.Flow/Classes/Command/MiddlewareCommandController.php b/Neos.Flow/Classes/Command/MiddlewareCommandController.php
index c05b0080da..cb2279355d 100644
--- a/Neos.Flow/Classes/Command/MiddlewareCommandController.php
+++ b/Neos.Flow/Classes/Command/MiddlewareCommandController.php
@@ -22,7 +22,7 @@ final class MiddlewareCommandController extends CommandController
 {
     /**
      * @Flow\InjectConfiguration(path="http.middlewares")
-     * @var array
+     * @var array<mixed>
      */
     protected $chainConfiguration;
 
diff --git a/Neos.Flow/Classes/Command/PackageCommandController.php b/Neos.Flow/Classes/Command/PackageCommandController.php
index f29fd399f3..b2ca710ceb 100644
--- a/Neos.Flow/Classes/Command/PackageCommandController.php
+++ b/Neos.Flow/Classes/Command/PackageCommandController.php
@@ -15,7 +15,6 @@
 use Neos\Flow\Cli\CommandController;
 use Neos\Flow\Composer\ComposerUtility;
 use Neos\Flow\Package\PackageInterface;
-use Neos\Flow\Package\PackageKeyAwareInterface;
 use Neos\Flow\Package\PackageManager;
 
 /**
@@ -97,7 +96,6 @@ public function listCommand(bool $loadingOrder = false)
         }
 
         $this->outputLine('PACKAGES:');
-        /** @var PackageInterface|PackageKeyAwareInterface $package */
         foreach ($availablePackages as $package) {
             $this->outputLine(' ' . str_pad($package->getPackageKey(), $longestPackageKey + 3) . str_pad($package->getInstalledVersion(), 15));
         }
@@ -106,7 +104,7 @@ public function listCommand(bool $loadingOrder = false)
     /**
      * Rescan package availability and recreates the PackageStates configuration.
      */
-    public function rescanCommand()
+    public function rescanCommand(): void
     {
         $packageStates = $this->packageManager->rescanPackages();
 
diff --git a/Neos.Flow/Classes/Command/ResourceCommandController.php b/Neos.Flow/Classes/Command/ResourceCommandController.php
index 60075d7cfb..c3d9b4a5a6 100644
--- a/Neos.Flow/Classes/Command/ResourceCommandController.php
+++ b/Neos.Flow/Classes/Command/ResourceCommandController.php
@@ -249,13 +249,9 @@ public function cleanCommand()
             foreach ($brokenResources as $resource) {
                 if ($mediaPackagePresent) {
                     $assets = $assetRepository->findByResource($resource);
-                    if ($assets !== null) {
-                        $relatedAssets[$resource] = $assets;
-                    }
+                    $relatedAssets[$resource] = $assets;
                     $thumbnails = $thumbnailRepository->findByResource($resource);
-                    if ($assets !== null) {
-                        $relatedThumbnails[$resource] = $thumbnails;
-                    }
+                    $relatedThumbnails[$resource] = $thumbnails;
                 }
             }
         }
@@ -306,6 +302,7 @@ public function cleanCommand()
                         $this->persistenceManager->persistAll();
                     }
                     $brokenResourcesCounter = count($brokenResources);
+                    /** @phpstan-ignore greater.alwaysTrue (not sure about this) */
                     if ($brokenResourcesCounter > 0) {
                         $this->outputLine('Removed %s resource object(s) from the database.', [$brokenResourcesCounter]);
                     }
@@ -319,7 +316,6 @@ public function cleanCommand()
                 case 'n':
                     $this->outputLine('Did not delete any resource objects.');
                     $this->quit(0);
-                    break;
             }
         }
     }
diff --git a/Neos.Flow/Classes/Command/RoutingCommandController.php b/Neos.Flow/Classes/Command/RoutingCommandController.php
index 18d932d542..32678b5749 100644
--- a/Neos.Flow/Classes/Command/RoutingCommandController.php
+++ b/Neos.Flow/Classes/Command/RoutingCommandController.php
@@ -23,7 +23,6 @@
 use Neos\Flow\Mvc\Routing\Dto\RouteContext;
 use Neos\Flow\Mvc\Routing\Dto\RouteParameters;
 use Neos\Flow\Mvc\Routing\Dto\RouteTags;
-use Neos\Flow\Mvc\Routing\Dto\UriConstraints;
 use Neos\Flow\Mvc\Routing\Route;
 use Neos\Flow\Mvc\Routing\RoutesProviderInterface;
 use Neos\Flow\ObjectManagement\ObjectManagerInterface;
@@ -207,9 +206,8 @@ public function resolveCommand(string $package, ?string $controller = null, ?str
             $this->quit(1);
         }
 
-        /** @var UriConstraints $uriConstraints */
         $uriConstraints = $resolvedRoute->getResolvedUriConstraints();
-        $resolvedUri = $uriConstraints->applyTo($resolveContext->getBaseUri(), $resolveContext->isForceAbsoluteUri());
+        $resolvedUri = $uriConstraints?->applyTo($resolveContext->getBaseUri(), $resolveContext->isForceAbsoluteUri()) ?: $resolveContext->getBaseUri();
 
         $this->outputLine('<b><success>Route resolved!</success></b>');
         $this->outputLine('<b>Name:</b> %s', [$resolvedRoute->getName()]);
@@ -299,7 +297,7 @@ public function matchCommand(string $uri, ?string $method = null, ?string $param
 
         $this->outputLine();
         $this->outputLine('<b>Results:</b>');
-        $matchResults = $matchedRoute->getMatchResults();
+        $matchResults = $matchedRoute->getMatchResults() ?: [];
         $this->outputArray($matchResults, 2);
 
         $this->outputLine();
@@ -338,7 +336,7 @@ private function createRouteParametersFromJson(?string $json): RouteParameters
      * Parses the given JSON string as array
      *
      * @param string|null $json
-     * @return array
+     * @return array<mixed>
      * @throws StopCommandException
      */
     private function parseJsonToArray(?string $json): array
@@ -361,7 +359,7 @@ private function parseJsonToArray(?string $json): array
     /**
      * Outputs a (potentially multi-dimensional) array to the console
      *
-     * @param array $array
+     * @param array<mixed> $array
      * @param int $indention
      */
     private function outputArray(array $array, int $indention): void
@@ -391,7 +389,11 @@ private function outputArray(array $array, int $indention): void
      */
     private function outputControllerObjectName(string $package, ?string $subpackage, ?string $controller): void
     {
-        $possibleControllerObjectName = str_replace(['@package', '@subpackage', '@controller', '\\\\'], [str_replace('.', '\\', $package), $subpackage, $controller, '\\'], '@package\@subpackage\Controller\@controllerController');
+        $possibleControllerObjectName = str_replace(
+            ['@package', '@subpackage', '@controller', '\\\\'],
+            array_filter([str_replace('.', '\\', $package), $subpackage, $controller, '\\']),
+            '@package\@subpackage\Controller\@controllerController'
+        );
         $controllerObjectName = $this->objectManager->getCaseSensitiveObjectName($possibleControllerObjectName);
         if ($controllerObjectName === null) {
             $this->outputLine('<error>%s</error> (no corresponding class exists)', [$possibleControllerObjectName]);
diff --git a/Neos.Flow/Classes/Command/SecurityCommandController.php b/Neos.Flow/Classes/Command/SecurityCommandController.php
index c33dc1f8d2..c677eeb476 100644
--- a/Neos.Flow/Classes/Command/SecurityCommandController.php
+++ b/Neos.Flow/Classes/Command/SecurityCommandController.php
@@ -89,6 +89,9 @@ public function importPublicKeyCommand()
         $keyData = '';
         // no file_get_contents here because it does not work on php://stdin
         $fp = fopen('php://stdin', 'rb');
+        if ($fp === false) {
+            throw new \RuntimeException('Unable to open php://stdin', 1744497200);
+        }
         while (!feof($fp)) {
             $keyData .= fgets($fp, 4096);
         }
@@ -144,6 +147,9 @@ public function importPrivateKeyCommand(bool $usedForPasswords = false)
         $keyData = '';
         // no file_get_contents here because it does not work on php://stdin
         $fp = fopen('php://stdin', 'rb');
+        if ($fp === false) {
+            throw new \RuntimeException('Unable to open php://stdin', 1744497170);
+        }
         while (!feof($fp)) {
             $keyData .= fgets($fp, 4096);
         }
@@ -160,7 +166,7 @@ public function importPrivateKeyCommand(bool $usedForPasswords = false)
      * @param string $privilegeType The privilege type ("entity", "method" or the FQN of a class implementing PrivilegeInterface)
      * @param string $roles A comma separated list of role identifiers. Shows policy for an unauthenticated user when left empty.
      */
-    public function showEffectivePolicyCommand(string $privilegeType, string $roles = '')
+    public function showEffectivePolicyCommand(string $privilegeType, string $roles = ''): void
     {
         $systemRoleIdentifiers = ['Neos.Flow:Everybody', 'Neos.Flow:Anonymous', 'Neos.Flow:AuthenticatedUser'];
 
@@ -323,11 +329,7 @@ public function showMethodsForPrivilegeTargetCommand(string $privilegeTarget)
 
         $matchedClassesAndMethods = [];
         foreach ($this->reflectionService->getAllClassNames() as $className) {
-            try {
-                $reflectionClass = new \ReflectionClass($className);
-            } catch (\ReflectionException $exception) {
-                continue;
-            }
+            $reflectionClass = new \ReflectionClass($className);
             foreach ($reflectionClass->getMethods() as $reflectionMethod) {
                 $methodName = $reflectionMethod->getName();
                 if ($privilege->matchesMethod($className, $methodName)) {
diff --git a/Neos.Flow/Classes/Command/ServerCommandController.php b/Neos.Flow/Classes/Command/ServerCommandController.php
index 8effb1c4b6..775dec137a 100644
--- a/Neos.Flow/Classes/Command/ServerCommandController.php
+++ b/Neos.Flow/Classes/Command/ServerCommandController.php
@@ -24,7 +24,14 @@ class ServerCommandController extends CommandController
 {
     /**
      * @Flow\InjectConfiguration
-     * @var array
+     * @var array{
+     *      core: array{
+     *          context: string,
+     *          phpBinaryPathAndFilename: string,
+     *          subRequestPhpIniPathAndFilename?: mixed,
+     *          subRequestEnvironmentVariables?: array<mixed>,
+     *      },
+     *  }
      */
     protected $settings;
 
diff --git a/Neos.Flow/Classes/Composer/ComposerUtility.php b/Neos.Flow/Classes/Composer/ComposerUtility.php
index 499cda76af..206db2954e 100644
--- a/Neos.Flow/Classes/Composer/ComposerUtility.php
+++ b/Neos.Flow/Classes/Composer/ComposerUtility.php
@@ -26,14 +26,14 @@ class ComposerUtility
     /**
      * Runtime cache for composer.json data
      *
-     * @var array
+     * @var array<string,array<string,mixed>>
      */
     protected static $composerManifestCache;
 
     /**
      * Runtime cache for composer.lock data
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected static $composerLockCache;
 
@@ -41,15 +41,12 @@ class ComposerUtility
      * Returns contents of Composer manifest - or part there of.
      *
      * @param string $manifestPath
-     * @param string $configurationPath Optional. Only return the part of the manifest indexed by configurationPath
-     * @return array|mixed
+     * @param ?string $configurationPath Optional. Only return the part of the manifest indexed by configurationPath
+     * @return mixed
      */
     public static function getComposerManifest(string $manifestPath, ?string $configurationPath = null)
     {
         $composerManifest = static::readComposerManifest($manifestPath);
-        if ($composerManifest === null) {
-            return null;
-        }
 
         if ($configurationPath !== null) {
             return ObjectAccess::getPropertyPath($composerManifest, $configurationPath);
@@ -60,7 +57,7 @@ public static function getComposerManifest(string $manifestPath, ?string $config
     /**
      * Read the content of the composer.lock
      *
-     * @return array
+     * @return array<string,mixed>
      */
     public static function readComposerLock(): array
     {
@@ -72,8 +69,8 @@ public static function readComposerLock(): array
             return [];
         }
 
-        $json = file_get_contents(FLOW_PATH_ROOT . 'composer.lock');
-        $composerLock = json_decode($json, true);
+        $json = file_get_contents(FLOW_PATH_ROOT . 'composer.lock') ?: '';
+        $composerLock = json_decode($json, true, flags: JSON_THROW_ON_ERROR);
         $composerPackageVersions = isset($composerLock['packages']) ? $composerLock['packages'] : [];
         $composerPackageDevVersions = isset($composerLock['packages-dev']) ? $composerLock['packages-dev'] : [];
         self::$composerLockCache = array_merge($composerPackageVersions, $composerPackageDevVersions);
@@ -85,7 +82,7 @@ public static function readComposerLock(): array
      * Read the content of composer.json in the given path
      *
      * @param string $manifestPath
-     * @return array
+     * @return array<string,mixed>
      * @throws Exception\MissingPackageManifestException
      */
     protected static function readComposerManifest(string $manifestPath): array
@@ -98,8 +95,8 @@ protected static function readComposerManifest(string $manifestPath): array
         if (!is_file($manifestPathAndFilename)) {
             throw new Exception\MissingPackageManifestException(sprintf('No composer manifest file found at "%s".', $manifestPathAndFilename), 1349868540);
         }
-        $json = file_get_contents($manifestPathAndFilename);
-        $composerManifest = json_decode($json, true);
+        $json = file_get_contents($manifestPathAndFilename) ?: '';
+        $composerManifest = json_decode($json, true, flags: JSON_THROW_ON_ERROR);
 
         if ($composerManifest === null) {
             throw new Exception\InvalidPackageManifestException(sprintf('The composer manifest file found at "%s" could not be parsed. Check for JSON syntax errors!', $manifestPathAndFilename), 1493909988);
@@ -131,8 +128,8 @@ public static function isFlowPackageType(string $packageType): bool
      *
      * @param string $manifestPath
      * @param FlowPackageKey $packageKey
-     * @param array $composerManifestData
-     * @return array the manifest data written
+     * @param array<string,mixed> $composerManifestData
+     * @return array<string,mixed> the manifest data written
      */
     public static function writeComposerManifest(string $manifestPath, FlowPackageKey $packageKey, array $composerManifestData = []): array
     {
@@ -140,9 +137,7 @@ public static function writeComposerManifest(string $manifestPath, FlowPackageKe
             'description' => ''
         ];
 
-        if ($composerManifestData !== null) {
-            $manifest = array_merge($manifest, $composerManifestData);
-        }
+        $manifest = array_merge($manifest, $composerManifestData);
         if (!isset($manifest['name']) || empty($manifest['name'])) {
             $manifest['name'] = $packageKey->deriveComposerPackageName();
         }
diff --git a/Neos.Flow/Classes/Composer/InstallerScripts.php b/Neos.Flow/Classes/Composer/InstallerScripts.php
index b39e588429..ca0325e324 100644
--- a/Neos.Flow/Classes/Composer/InstallerScripts.php
+++ b/Neos.Flow/Classes/Composer/InstallerScripts.php
@@ -37,19 +37,23 @@ class InstallerScripts
      */
     public static function postUpdateAndInstall(Event $event): void
     {
+        $workingDirectory = getcwd();
+        if ($workingDirectory === false) {
+            throw new \RuntimeException('Could not resolve working directory', 1744470280);
+        }
         if (!defined('FLOW_PATH_ROOT')) {
-            define('FLOW_PATH_ROOT', Files::getUnixStylePath(getcwd()) . '/');
+            define('FLOW_PATH_ROOT', Files::getUnixStylePath($workingDirectory) . '/');
         }
 
         if (!defined('FLOW_PATH_PACKAGES')) {
-            define('FLOW_PATH_PACKAGES', Files::getUnixStylePath(getcwd()) . '/Packages/');
+            define('FLOW_PATH_PACKAGES', Files::getUnixStylePath($workingDirectory) . '/Packages/');
         }
 
         if (!defined('FLOW_PATH_CONFIGURATION')) {
-            define('FLOW_PATH_CONFIGURATION', Files::getUnixStylePath(getcwd()) . '/Configuration/');
+            define('FLOW_PATH_CONFIGURATION', Files::getUnixStylePath($workingDirectory) . '/Configuration/');
         }
         if (!defined('FLOW_PATH_TEMPORARY_BASE')) {
-            define('FLOW_PATH_TEMPORARY_BASE', Files::getUnixStylePath(getcwd()) . '/Data/Temporary');
+            define('FLOW_PATH_TEMPORARY_BASE', Files::getUnixStylePath($workingDirectory) . '/Data/Temporary');
         }
 
         Files::createDirectoryRecursively('Configuration');
@@ -106,14 +110,19 @@ public static function postPackageUpdateAndInstall(PackageEvent $event): void
      */
     protected static function copyDistributionFiles(string $installerResourcesDirectory): void
     {
+        $workingDirectory = getcwd();
+        if ($workingDirectory === false) {
+            throw new \RuntimeException('Could not resolve working directory', 1744470280);
+        }
+
         $essentialsPath = $installerResourcesDirectory . 'Distribution/Essentials';
         if (is_dir($essentialsPath)) {
-            Files::copyDirectoryRecursively($essentialsPath, Files::getUnixStylePath(getcwd()) . '/', false, true);
+            Files::copyDirectoryRecursively($essentialsPath, Files::getUnixStylePath($workingDirectory) . '/', false, true);
         }
 
         $defaultsPath = $installerResourcesDirectory . 'Distribution/Defaults';
         if (is_dir($defaultsPath)) {
-            Files::copyDirectoryRecursively($defaultsPath, Files::getUnixStylePath(getcwd()) . '/', true, true);
+            Files::copyDirectoryRecursively($defaultsPath, Files::getUnixStylePath($workingDirectory) . '/', true, true);
         }
     }
 
@@ -127,7 +136,7 @@ protected static function copyDistributionFiles(string $installerResourcesDirect
      */
     protected static function runPackageScripts(string $staticMethodReference, PackageEvent $event): void
     {
-        $className = substr($staticMethodReference, 0, strpos($staticMethodReference, '::'));
+        $className = substr($staticMethodReference, 0, strpos($staticMethodReference, '::') ?: 0);
         $methodName = substr($staticMethodReference, strpos($staticMethodReference, '::') + 2);
 
         if (!class_exists($className)) {
diff --git a/Neos.Flow/Classes/Configuration/ConfigurationManager.php b/Neos.Flow/Classes/Configuration/ConfigurationManager.php
index a9d0c092f8..454aadbb1c 100644
--- a/Neos.Flow/Classes/Configuration/ConfigurationManager.php
+++ b/Neos.Flow/Classes/Configuration/ConfigurationManager.php
@@ -135,7 +135,7 @@ class ConfigurationManager
     /**
      * Storage of the raw special configurations
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected $configurations = [];
 
@@ -159,7 +159,7 @@ class ConfigurationManager
     protected $temporaryDirectoryPath = null;
 
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $unprocessedConfiguration = [];
 
@@ -224,14 +224,10 @@ public function registerConfigurationType(string $configurationType, $configurat
     {
         if ($configurationLoader === null) {
             $configurationLoader = new MergeLoader(new YamlSource(), $configurationType);
-
-        // B/C layer
         } elseif (is_string($configurationLoader)) {
+            // B/C layer
             $configurationLoader = $this->convertLegacyProcessingType($configurationType, $configurationLoader);
         }
-        if (!$configurationLoader instanceof LoaderInterface) {
-            throw new \InvalidArgumentException(sprintf('Specified invalid configuration loader of type "%s" while registering custom configuration type "%s". This should be an instance of %s', is_object($configurationLoader) ? get_class($configurationLoader) : gettype($configurationLoader), $configurationType, LoaderInterface::class), 1617895964);
-        }
 
         // if the configuration was already registered and the there is an unprocessed loaded configuration, the configuration needs to be loaded again
         // on the other hand, if there is a processed configuration loaded, but no unprocessed configuration, the config must be from the cache and is assumed to be valid
@@ -308,7 +304,6 @@ public function getConfiguration(string $configurationType, ?string $configurati
      * This method writes the current configuration into a cache file if Flow was configured to do so.
      *
      * @return void
-     * @throws Exception\InvalidConfigurationException
      * @throws Exception\InvalidConfigurationTypeException
      * @throws FilesException
      */
@@ -419,7 +414,7 @@ public function flushConfigurationCache(): void
      *
      * @param string $configurationType The kind of configuration to fetch
      */
-    protected function processConfigurationType(string $configurationType)
+    protected function processConfigurationType(string $configurationType): void
     {
         if ($this->temporaryDirectoryPath !== null) {
             // to avoid issues regarding concurrency and invalid filesystem characters
@@ -524,7 +519,7 @@ protected function replaceVariablesInPhpString(string $phpString): string
             }
             $replacement .= ($constantDoesNotStartAsBeginning ? $matchGroup['startString'] . "' . " : '=> ');
 
-            if (isset($matchGroup['prefix']) && $matchGroup['prefix'] === 'env') {
+            if ($matchGroup['prefix'] === 'env') {
                 if ($matchGroup['type'] === 'bool') {
                     $replacement .= "!in_array(strtolower(getenv('" . $matchGroup['name'] . "')), ['', '0', 'false'], true)";
                 } elseif ($matchGroup['type'] !== '') {
@@ -532,7 +527,7 @@ protected function replaceVariablesInPhpString(string $phpString): string
                 } else {
                     $replacement .= "getenv('" . $matchGroup['name'] . "')";
                 }
-            } elseif (isset($matchGroup['expression'])) {
+            } else {
                 $replacement .= "(defined('" . $matchGroup['expression'] . "') ? constant('" . $matchGroup['expression'] . "') : null)";
             }
 
@@ -548,7 +543,11 @@ protected function replaceVariablesInPhpString(string $phpString): string
             return $replacement;
         }, $phpString);
 
-        return $phpString;
+        if (is_string($phpString)) {
+            return $phpString;
+        }
+
+        throw new \RuntimeException('Failed to render PHP string', 1744468312);
     }
 
     /**
diff --git a/Neos.Flow/Classes/Configuration/ConfigurationSchemaValidator.php b/Neos.Flow/Classes/Configuration/ConfigurationSchemaValidator.php
index 279c0bee90..1b2d70e599 100644
--- a/Neos.Flow/Classes/Configuration/ConfigurationSchemaValidator.php
+++ b/Neos.Flow/Classes/Configuration/ConfigurationSchemaValidator.php
@@ -64,9 +64,9 @@ class ConfigurationSchemaValidator
     /**
      * Validate the given $configurationType and $path
      *
-     * @param string $configurationType (optional) the configuration type to validate. if NULL, validates all configuration.
-     * @param string $path (optional) configuration path to validate
-     * @param array $loadedSchemaFiles (optional). if given, will be filled with a list of loaded schema files
+     * @param ?string $configurationType (optional) the configuration type to validate. if NULL, validates all configuration.
+     * @param ?string $path (optional) configuration path to validate
+     * @param array<int,string> $loadedSchemaFiles (optional). if given, will be filled with a list of loaded schema files
      * @return \Neos\Error\Messages\Result the result of the validation
      * @throws Exception\SchemaValidationException
      */
@@ -91,7 +91,7 @@ public function validate(?string $configurationType = null, ?string $path = null
      *
      * @param string $configurationType the configuration typr to validate
      * @param string|null $path configuration path to validate, or NULL.
-     * @param array $loadedSchemaFiles will be filled with a list of loaded schema files
+     * @param array<int,string> $loadedSchemaFiles will be filled with a list of loaded schema files
      * @return \Neos\Error\Messages\Result
      * @throws Exception\SchemaValidationException
      */
@@ -121,7 +121,7 @@ protected function validateSingleType(string $configurationType, ?string $path =
                     $schemaType = $schemaNameParts[0];
                     $schemaPath = isset($schemaNameParts[1]) ? $schemaNameParts[1] : null;
 
-                    if ($schemaType === $configurationType && ($path === null || strpos($schemaPath, $path) === 0)) {
+                    if ($schemaPath && $schemaType === $configurationType && ($path === null || str_starts_with($schemaPath, $path))) {
                         $schemaFileInfos[] = [
                             'file' => $schemaFile,
                             'name' => $schemaName,
@@ -138,6 +138,7 @@ protected function validateSingleType(string $configurationType, ?string $path =
         }
 
         $result = new Result();
+        /** @var array<int,array{file: string, name: string, path: ?string, packageKey: string}> $schemaFileInfos */
         foreach ($schemaFileInfos as $schemaFileInfo) {
             $loadedSchemaFiles[] = $schemaFileInfo['file'];
 
diff --git a/Neos.Flow/Classes/Configuration/Loader/AppendLoader.php b/Neos.Flow/Classes/Configuration/Loader/AppendLoader.php
index c9de87c21c..d0cf76e366 100644
--- a/Neos.Flow/Classes/Configuration/Loader/AppendLoader.php
+++ b/Neos.Flow/Classes/Configuration/Loader/AppendLoader.php
@@ -15,6 +15,7 @@
 
 use Neos\Flow\Configuration\Source\YamlSource;
 use Neos\Flow\Core\ApplicationContext;
+use Neos\Flow\Package\FlowPackageInterface;
 
 class AppendLoader implements LoaderInterface
 {
@@ -34,6 +35,10 @@ public function __construct(YamlSource $yamlSource, string $filePrefix)
         $this->filePrefix = $filePrefix;
     }
 
+    /**
+     * @param array<FlowPackageInterface> $packages
+     * @return array<int,array<mixed>>
+     */
     public function load(array $packages, ApplicationContext $context): array
     {
         $configuration = [];
diff --git a/Neos.Flow/Classes/Configuration/Loader/LoaderInterface.php b/Neos.Flow/Classes/Configuration/Loader/LoaderInterface.php
index 2a43031b37..a2dbe8f0ce 100644
--- a/Neos.Flow/Classes/Configuration/Loader/LoaderInterface.php
+++ b/Neos.Flow/Classes/Configuration/Loader/LoaderInterface.php
@@ -14,6 +14,7 @@
  */
 
 use Neos\Flow\Core\ApplicationContext;
+use Neos\Flow\Package\PackageInterface;
 
 /**
  * The interface for a configuration loader
@@ -23,9 +24,9 @@ interface LoaderInterface
     /**
      * Read configuration resources and return the final configuration array for the given configurationType
      *
-     * @param array $packages An array of Package objects (indexed by package key) to consider
+     * @param array<PackageInterface> $packages An array of Package objects (indexed by package key) to consider
      * @param ApplicationContext $context
-     * @return array The Configuration array for the current configurationType
+     * @return array<mixed> The Configuration array for the current configurationType
      */
     public function load(array $packages, ApplicationContext $context) : array;
 }
diff --git a/Neos.Flow/Classes/Configuration/Loader/MergeLoader.php b/Neos.Flow/Classes/Configuration/Loader/MergeLoader.php
index 322573ce3a..67a9470c53 100644
--- a/Neos.Flow/Classes/Configuration/Loader/MergeLoader.php
+++ b/Neos.Flow/Classes/Configuration/Loader/MergeLoader.php
@@ -15,6 +15,7 @@
 
 use Neos\Flow\Configuration\Source\YamlSource;
 use Neos\Flow\Core\ApplicationContext;
+use Neos\Flow\Package\FlowPackageInterface;
 use Neos\Utility\Arrays;
 
 class MergeLoader implements LoaderInterface
@@ -35,6 +36,10 @@ public function __construct(YamlSource $yamlSource, string $filePrefix)
         $this->filePrefix = $filePrefix;
     }
 
+    /**
+     * @param array<FlowPackageInterface> $packages
+     * @return array<mixed>
+     */
     public function load(array $packages, ApplicationContext $context): array
     {
         $configuration = [];
diff --git a/Neos.Flow/Classes/Configuration/Loader/ObjectsLoader.php b/Neos.Flow/Classes/Configuration/Loader/ObjectsLoader.php
index ec0fb02c55..821f023554 100644
--- a/Neos.Flow/Classes/Configuration/Loader/ObjectsLoader.php
+++ b/Neos.Flow/Classes/Configuration/Loader/ObjectsLoader.php
@@ -16,6 +16,7 @@
 use Neos\Flow\Configuration\ConfigurationManager;
 use Neos\Flow\Configuration\Source\YamlSource;
 use Neos\Flow\Core\ApplicationContext;
+use Neos\Flow\Package\FlowPackageInterface;
 use Neos\Utility\Arrays;
 
 class ObjectsLoader implements LoaderInterface
@@ -30,6 +31,10 @@ public function __construct(YamlSource $yamlSource)
         $this->yamlSource = $yamlSource;
     }
 
+    /**
+     * @param array<string, FlowPackageInterface> $packages
+     * @return array<string,array<mixed>>
+     */
     public function load(array $packages, ApplicationContext $context): array
     {
         $configuration = [];
diff --git a/Neos.Flow/Classes/Configuration/Loader/PolicyLoader.php b/Neos.Flow/Classes/Configuration/Loader/PolicyLoader.php
index 05fcae91c7..9c2a4b33de 100644
--- a/Neos.Flow/Classes/Configuration/Loader/PolicyLoader.php
+++ b/Neos.Flow/Classes/Configuration/Loader/PolicyLoader.php
@@ -16,8 +16,12 @@
 use Neos\Flow\Configuration\ConfigurationManager;
 use Neos\Flow\Configuration\Source\YamlSource;
 use Neos\Flow\Core\ApplicationContext;
+use Neos\Flow\Package\FlowPackageInterface;
 use Neos\Utility\Arrays;
 
+/**
+ * @phpstan-type PolicyDefinition array{roles?: array<string, array{privileges: array<mixed>}>}
+ */
 class PolicyLoader implements LoaderInterface
 {
     /**
@@ -47,6 +51,10 @@ public function setTemporaryDirectoryPath(string $temporaryDirectoryPath): void
         $this->temporaryDirectoryPath = $temporaryDirectoryPath;
     }
 
+    /**
+     * @param array<FlowPackageInterface> $packages
+     * @return PolicyDefinition
+     */
     public function load(array $packages, ApplicationContext $context): array
     {
         if ($context->isTesting()) {
@@ -77,9 +85,9 @@ public function load(array $packages, ApplicationContext $context): array
     /**
      * Merges two policy configuration arrays.
      *
-     * @param array $firstConfigurationArray
-     * @param array $secondConfigurationArray
-     * @return array
+     * @param PolicyDefinition $firstConfigurationArray
+     * @param PolicyDefinition $secondConfigurationArray
+     * @return PolicyDefinition
      */
     private function mergePolicyConfiguration(array $firstConfigurationArray, array $secondConfigurationArray): array
     {
diff --git a/Neos.Flow/Classes/Configuration/Loader/RoutesLoader.php b/Neos.Flow/Classes/Configuration/Loader/RoutesLoader.php
index c3f5fb8da4..37efd6307a 100644
--- a/Neos.Flow/Classes/Configuration/Loader/RoutesLoader.php
+++ b/Neos.Flow/Classes/Configuration/Loader/RoutesLoader.php
@@ -26,6 +26,26 @@
 use Neos\Utility\Arrays;
 use Neos\Utility\PositionalArraySorter;
 
+/**
+ * @phpstan-type RouteDefinition array{
+ *      name: string,
+ *      providerFactory?: class-string,
+ *      providerOptions?: array<mixed>,
+ *      uriPattern?: string,
+ *      subRoutes?: array<string,array{
+ *          package: string,
+ *          variables?: array<mixed>,
+ *          suffix?: string,
+ *      }>
+ *  }
+ * @phpstan-type SubrouteDefinition array{
+ *     name?: string,
+ *     uriPattern?: string,
+ *     defaults?: mixed,
+ *     routeParts?: mixed,
+ *     subRoutes?: mixed,
+ * }
+ */
 class RoutesLoader implements LoaderInterface
 {
     /**
@@ -52,9 +72,9 @@ public function __construct(YamlSource $yamlSource, ConfigurationManager $config
     }
 
     /**
-     * @param array $packages
+     * @param array<PackageInterface> $packages
      * @param ApplicationContext $context
-     * @return array
+     * @return array<int,array<mixed>>
      * @throws ConfigurationException | InvalidConfigurationException | InvalidConfigurationTypeException | ParseErrorException | RecursionException
      */
     public function load(array $packages, ApplicationContext $context): array
@@ -77,9 +97,9 @@ public function load(array $packages, ApplicationContext $context): array
      * Merges routes from Neos.Flow.mvc.routes settings into $routeDefinitions
      * NOTE: Routes from settings will always be appended to existing route definitions from the main Routes configuration!
      *
-     * @param array $routeDefinitions
-     * @param array $routeSettings
-     * @return array
+     * @param array<int,RouteDefinition> $routeDefinitions
+     * @param array<mixed> $routeSettings
+     * @return array<int,RouteDefinition>
      */
     protected function includeSubRoutesFromSettings(array $routeDefinitions, array $routeSettings): array
     {
@@ -121,9 +141,9 @@ protected function includeSubRoutesFromSettings(array $routeDefinitions, array $
      *
      * @param PackageInterface[] $packages
      * @param ApplicationContext $context
-     * @param array $routesConfiguration
+     * @param array<mixed> $routesConfiguration
      * @param int $subRoutesRecursionLevel Counts how many SubRoutes have been loaded. If this number exceeds MAXIMUM_SUBROUTE_RECURSIONS, an exception is thrown
-     * @return array
+     * @return array<int,array<mixed>>
      * @throws ParseErrorException | RecursionException| ConfigurationException
      */
     protected function mergeRoutesWithSubRoutes(array $packages, ApplicationContext $context, array $routesConfiguration, int $subRoutesRecursionLevel = 0): array
@@ -176,11 +196,11 @@ protected function mergeRoutesWithSubRoutes(array $packages, ApplicationContext
     /**
      * Merges all routes in $routesConfiguration with the sub routes in $subRoutesConfiguration
      *
-     * @param array $routesConfiguration
-     * @param array $subRoutesConfiguration
+     * @param array<array{name?: string, uriPattern: string}> $routesConfiguration
+     * @param array<SubrouteDefinition> $subRoutesConfiguration
      * @param string $subRouteKey the key of the sub route: <subRouteKey>
-     * @param array $subRouteOptions
-     * @return array the merged route configuration
+     * @param array{variables?: array<mixed>} $subRouteOptions
+     * @return array<int,SubrouteDefinition> the merged route configuration
      * @throws ParseErrorException
      */
     protected function buildSubRouteConfigurations(array $routesConfiguration, array $subRoutesConfiguration, string $subRouteKey, array $subRouteOptions): array
@@ -190,7 +210,11 @@ protected function buildSubRouteConfigurations(array $routesConfiguration, array
         foreach ($subRoutesConfiguration as $subRouteConfiguration) {
             foreach ($routesConfiguration as $routeConfiguration) {
                 $mergedSubRouteConfiguration = $subRouteConfiguration;
-                $mergedSubRouteConfiguration['name'] = sprintf('%s :: %s', $routeConfiguration['name'] ?? 'Unnamed Route', $subRouteConfiguration['name'] ?? 'Unnamed Subroute');
+                $mergedSubRouteConfiguration['name'] = sprintf(
+                    '%s :: %s',
+                    $routeConfiguration['name'] ?? 'Unnamed Route',
+                    $subRouteConfiguration['name'] ?? 'Unnamed Subroute'
+                );
                 $mergedSubRouteConfiguration['name'] = $this->replacePlaceholders($mergedSubRouteConfiguration['name'], $variables);
                 if (!isset($mergedSubRouteConfiguration['uriPattern'])) {
                     throw new ParseErrorException('No uriPattern defined in route configuration "' . $mergedSubRouteConfiguration['name'] . '".', 1274197615);
@@ -207,6 +231,7 @@ protected function buildSubRouteConfigurations(array $routesConfiguration, array
                 if (isset($mergedSubRouteConfiguration['routeParts'])) {
                     $mergedSubRouteConfiguration['routeParts'] = $this->replacePlaceholders($mergedSubRouteConfiguration['routeParts'], $variables);
                 }
+                /** @var SubrouteDefinition $mergedSubRouteConfiguration arrayMergeRecursiveOverrule does not change that */
                 $mergedSubRouteConfiguration = Arrays::arrayMergeRecursiveOverrule($routeConfiguration, $mergedSubRouteConfiguration);
                 unset($mergedSubRouteConfiguration['subRoutes']);
                 $mergedSubRoutesConfigurations[] = $mergedSubRouteConfiguration;
@@ -219,9 +244,10 @@ protected function buildSubRouteConfigurations(array $routesConfiguration, array
     /**
      * Replaces placeholders in the format <variableName> with the corresponding variable of the specified $variables collection.
      *
-     * @param string|array $value
-     * @param array $variables
-     * @return array|string
+     * @param string|array<mixed> $value
+     * @param array<mixed> $variables
+     *
+     * @return ($value is string ? string : array<mixed>)
      */
     private function replacePlaceholders($value, array $variables)
     {
diff --git a/Neos.Flow/Classes/Configuration/Loader/SettingsLoader.php b/Neos.Flow/Classes/Configuration/Loader/SettingsLoader.php
index c5d08f3524..1d136aa3cc 100644
--- a/Neos.Flow/Classes/Configuration/Loader/SettingsLoader.php
+++ b/Neos.Flow/Classes/Configuration/Loader/SettingsLoader.php
@@ -16,6 +16,7 @@
 use Neos\Flow\Configuration\ConfigurationManager;
 use Neos\Flow\Configuration\Source\YamlSource;
 use Neos\Flow\Core\ApplicationContext;
+use Neos\Flow\Package\FlowPackageInterface;
 use Neos\Utility\Arrays;
 
 class SettingsLoader implements LoaderInterface
@@ -30,6 +31,10 @@ public function __construct(YamlSource $yamlSource)
         $this->yamlSource = $yamlSource;
     }
 
+    /**
+     * @param array<string,FlowPackageInterface> $packages
+     * @return array<mixed>
+     */
     public function load(array $packages, ApplicationContext $context): array
     {
         // Make sure that the Flow package is the first item of the packages array:
diff --git a/Neos.Flow/Classes/Configuration/Source/YamlSource.php b/Neos.Flow/Classes/Configuration/Source/YamlSource.php
index 7bcbd946bb..019df55f1d 100644
--- a/Neos.Flow/Classes/Configuration/Source/YamlSource.php
+++ b/Neos.Flow/Classes/Configuration/Source/YamlSource.php
@@ -76,7 +76,7 @@ public function has(string $pathAndFilename, bool $allowSplitSource = false): bo
      *
      * @param string $pathAndFilename Full path and filename of the file to load, excluding the file extension (ie. ".yaml")
      * @param boolean $allowSplitSource If true, the type will be used as a prefix when looking for configuration files
-     * @return array
+     * @return array<mixed>
      * @throws ParseErrorException
      * @throws \Neos\Flow\Configuration\Exception
      */
@@ -85,9 +85,9 @@ public function load(string $pathAndFilename, bool $allowSplitSource = false): a
         $this->detectFilesWithWrongExtension($pathAndFilename, $allowSplitSource);
         $pathsAndFileNames = [$pathAndFilename . '.yaml'];
         if ($allowSplitSource === true) {
-            $splitSourcePathsAndFileNames = glob($pathAndFilename . '.*.yaml');
-            $splitSourcePathsAndFileNames = array_merge($splitSourcePathsAndFileNames, glob($pathAndFilename . '.*.yml'));
-            if ($splitSourcePathsAndFileNames !== false) {
+            $splitSourcePathsAndFileNames = glob($pathAndFilename . '.*.yaml') ?: [];
+            $splitSourcePathsAndFileNames = array_merge($splitSourcePathsAndFileNames, glob($pathAndFilename . '.*.yml') ?: []);
+            if ($splitSourcePathsAndFileNames != []) {
                 sort($splitSourcePathsAndFileNames);
                 $pathsAndFileNames = array_merge($pathsAndFileNames, $splitSourcePathsAndFileNames);
             }
@@ -104,7 +104,7 @@ public function load(string $pathAndFilename, bool $allowSplitSource = false): a
      * @param bool $allowSplitSource
      * @throws \Neos\Flow\Configuration\Exception
      */
-    protected function detectFilesWithWrongExtension($pathAndFilename, $allowSplitSource = false)
+    protected function detectFilesWithWrongExtension($pathAndFilename, $allowSplitSource = false): void
     {
         $wrongPathsAndFileNames = [];
         if (is_file($pathAndFilename . '.yml')) {
@@ -125,8 +125,8 @@ protected function detectFilesWithWrongExtension($pathAndFilename, $allowSplitSo
      * Loads the file with the given path and merge it's contents into the configuration array.
      *
      * @param string $pathAndFilename
-     * @param array $configuration
-     * @return array
+     * @param array<mixed> $configuration
+     * @return array<mixed>
      * @throws ParseErrorException
      */
     protected function mergeFileContent(string $pathAndFilename, array $configuration): array
@@ -137,6 +137,9 @@ protected function mergeFileContent(string $pathAndFilename, array $configuratio
 
         try {
             $yaml = file_get_contents($pathAndFilename);
+            if ($yaml === false) {
+                throw new ParseErrorException('Failed to load content from file "' . $pathAndFilename . '".', 1744463546);
+            }
             if ($this->usePhpYamlExtension) {
                 $loadedConfiguration = @yaml_parse($yaml);
                 if ($loadedConfiguration === false) {
@@ -165,7 +168,7 @@ protected function mergeFileContent(string $pathAndFilename, array $configuratio
      * Save the specified configuration array to the given file in YAML format.
      *
      * @param string $pathAndFilename Full path and filename of the file to write to, excluding the dot and file extension (i.e. ".yaml")
-     * @param array $configuration The configuration to save
+     * @param array<mixed> $configuration The configuration to save
      * @return void
      */
     public function save(string $pathAndFilename, array $configuration)
@@ -189,14 +192,16 @@ protected function getHeaderFromFile(string $pathAndFilename): string
     {
         $header = '';
         $fileHandle = fopen($pathAndFilename, 'r');
-        while ($line = fgets($fileHandle)) {
-            if (preg_match('/^#/', $line)) {
-                $header .= $line;
-            } else {
-                break;
+        if ($fileHandle !== false) {
+            while ($line = fgets($fileHandle)) {
+                if (preg_match('/^#/', $line)) {
+                    $header .= $line;
+                } else {
+                    break;
+                }
             }
+            fclose($fileHandle);
         }
-        fclose($fileHandle);
         return $header;
     }
 }
diff --git a/Neos.Flow/Classes/Core/Booting/Scripts.php b/Neos.Flow/Classes/Core/Booting/Scripts.php
index 74edfed2e0..50ffe4cb57 100644
--- a/Neos.Flow/Classes/Core/Booting/Scripts.php
+++ b/Neos.Flow/Classes/Core/Booting/Scripts.php
@@ -13,6 +13,8 @@
 
 use Doctrine\Common\Annotations\AnnotationRegistry;
 use Neos\Cache\CacheFactoryInterface;
+use Neos\Cache\Frontend\PhpFrontend;
+use Neos\Cache\Frontend\VariableFrontend;
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\Cache\CacheFactory;
 use Neos\Flow\Cache\CacheManager;
@@ -30,6 +32,7 @@
 use Neos\Flow\Core\ProxyClassLoader;
 use Neos\Flow\Error\Debugger;
 use Neos\Flow\Error\ErrorHandler;
+use Neos\Flow\Error\ExceptionHandlerInterface;
 use Neos\Flow\Error\ProductionExceptionHandler;
 use Neos\Flow\Http\Helper\RequestInformationHelper;
 use Neos\Flow\Http\HttpRequestHandlerInterface;
@@ -40,8 +43,11 @@
 use Neos\Flow\ObjectManagement\CompileTimeObjectManager;
 use Neos\Flow\ObjectManagement\ObjectManager;
 use Neos\Flow\ObjectManagement\ObjectManagerInterface;
+use Neos\Flow\Package;
 use Neos\Flow\Package\FlowPackageInterface;
 use Neos\Flow\Package\GenericPackage;
+use Neos\Flow\Package\PackageInterface;
+use Neos\Flow\Package\PackageKeyAwareInterface;
 use Neos\Flow\Package\PackageManager;
 use Neos\Flow\Reflection\ReflectionService;
 use Neos\Flow\Reflection\ReflectionServiceFactory;
@@ -51,7 +57,6 @@
 use Neos\Utility\Files;
 use Neos\Utility\OpcodeCacheHelper;
 use Neos\Flow\Exception as FlowException;
-use Psr\Http\Message\RequestInterface;
 
 /**
  * Initialization scripts for modules of the Flow package
@@ -73,7 +78,8 @@ class Scripts
     public static function initializeClassLoader(Bootstrap $bootstrap)
     {
         $proxyClassLoader = new ProxyClassLoader($bootstrap->getContext());
-        spl_autoload_register([$proxyClassLoader, 'loadClass'], true, true);
+        /** @phpstan-ignore argument.type (we return boolean in the closure but void is expected) */
+        spl_autoload_register($proxyClassLoader->loadClass(...), true, true);
         $bootstrap->setEarlyInstance(ProxyClassLoader::class, $proxyClassLoader);
 
         if (!self::useClassLoader($bootstrap)) {
@@ -94,7 +100,8 @@ public static function initializeClassLoader(Bootstrap $bootstrap)
         ];
 
         $classLoader = new ClassLoader($initialClassLoaderMappings);
-        spl_autoload_register([$classLoader, 'loadClass'], true);
+        /** @phpstan-ignore argument.type (we return boolean in the closure but void is expected) */
+        spl_autoload_register($classLoader->loadClass(...), true);
         $bootstrap->setEarlyInstance(ClassLoader::class, $classLoader);
         $classLoader->setConsiderTestsNamespace(true);
     }
@@ -123,6 +130,9 @@ public static function registerClassLoaderInAnnotationRegistry(Bootstrap $bootst
     public static function initializeClassLoaderClassesCache(Bootstrap $bootstrap)
     {
         $classesCache = $bootstrap->getEarlyInstance(CacheManager::class)->getCache('Flow_Object_Classes');
+        if (!$classesCache instanceof PhpFrontend) {
+            throw new \Exception('The classes cache must be a PhpFrontend', 1744461618);
+        }
         $bootstrap->getEarlyInstance(ProxyClassLoader::class)->injectClassesCache($classesCache);
     }
 
@@ -185,7 +195,9 @@ public static function initializePackageManagement(Bootstrap $bootstrap)
 
         $packageManager->initialize($bootstrap);
         if (self::useClassLoader($bootstrap)) {
-            $bootstrap->getEarlyInstance(ClassLoader::class)->setPackages($packageManager->getAvailablePackages());
+            $bootstrap->getEarlyInstance(ClassLoader::class)->setPackages(
+                $packageManager->getAvailablePackages()
+            );
         }
     }
 
@@ -260,7 +272,15 @@ public static function initializeSystemLogger(Bootstrap $bootstrap): void
      * Initialize the exception storage
      *
      * @param Bootstrap $bootstrap
-     * @param array $settings The Neos.Flow settings
+     * @param array{
+     *     log?: array{
+     *         throwables?: array{
+     *             storageClass?: class-string<ThrowableStorageInterface>,
+     *             optionsByImplementation?: array<class-string<ThrowableStorageInterface>, array<mixed>>,
+     *             renderRequestInformation?: bool,
+     *         }
+     *     }
+     * } $settings The Neos.Flow settings
      * @return ThrowableStorageInterface
      * @throws FlowException
      * @throws InvalidConfigurationTypeException
@@ -271,7 +291,6 @@ protected static function initializeExceptionStorage(Bootstrap $bootstrap, array
         $storageOptions = $settings['log']['throwables']['optionsByImplementation'][$storageClassName] ?? [];
         $renderRequestInformation = $settings['log']['throwables']['renderRequestInformation'] ?? true;
 
-
         if (!in_array(ThrowableStorageInterface::class, class_implements($storageClassName, true))) {
             throw new \Exception(
                 sprintf('The class "%s" configured as throwable storage does not implement the ThrowableStorageInterface', $storageClassName),
@@ -304,7 +323,7 @@ protected static function initializeExceptionStorage(Bootstrap $bootstrap, array
 
             $request = $requestHandler->getHttpRequest();
             if ($renderRequestInformation) {
-                $output .= PHP_EOL . 'HTTP REQUEST:' . PHP_EOL . ($request instanceof RequestInterface ? RequestInformationHelper::renderRequestInformation($request) : '[request was empty]') . PHP_EOL;
+                $output .= PHP_EOL . 'HTTP REQUEST:' . PHP_EOL . RequestInformationHelper::renderRequestInformation($request) . PHP_EOL;
             }
             $output .= PHP_EOL . 'PHP PROCESS:' . PHP_EOL . 'Inode: ' . getmyinode() . PHP_EOL . 'PID: ' . getmypid() . PHP_EOL . 'UID: ' . getmyuid() . PHP_EOL . 'GID: ' . getmygid() . PHP_EOL . 'User: ' . get_current_user() . PHP_EOL;
 
@@ -325,11 +344,25 @@ protected static function initializeExceptionStorage(Bootstrap $bootstrap, array
     public static function initializeErrorHandling(Bootstrap $bootstrap)
     {
         $configurationManager = $bootstrap->getEarlyInstance(ConfigurationManager::class);
+        /**
+         * @var array{
+         *     error: array{
+         *         errorHandler: array{
+         *             exceptionalErrors: array<int>,
+         *         },
+         *         exceptionHandler: array{
+         *             className: class-string<ExceptionHandlerInterface>,
+         *         }
+         *     }
+         * } $settings
+         */
         $settings = $configurationManager->getConfiguration(ConfigurationManager::CONFIGURATION_TYPE_SETTINGS, 'Neos.Flow');
 
         $errorHandler = new ErrorHandler();
         $errorHandler->setExceptionalErrors($settings['error']['errorHandler']['exceptionalErrors']);
-        $exceptionHandler = class_exists($settings['error']['exceptionHandler']['className']) ? new $settings['error']['exceptionHandler']['className'] : new ProductionExceptionHandler();
+        $exceptionHandler = class_exists($settings['error']['exceptionHandler']['className'])
+            ? new $settings['error']['exceptionHandler']['className']
+            : new ProductionExceptionHandler();
 
         if (is_callable([$exceptionHandler, 'injectLogger'])) {
             $exceptionHandler->injectLogger($bootstrap->getEarlyInstance(PsrLoggerFactoryInterface::class)->get('systemLogger'));
@@ -415,13 +448,18 @@ public static function initializeProxyClasses(Bootstrap $bootstrap)
         $proxyClassLoader->initializeAvailableProxyClasses($bootstrap->getContext());
 
         // Check if code was updated, if not something went wrong
+        /** @phpstan-ignore identical.alwaysTrue (could have changed on code update) */
         if ($objectConfigurationCache->has('allCompiledCodeUpToDate') === false) {
             if (DIRECTORY_SEPARATOR === '/') {
                 $phpBinaryPathAndFilename = '"' . escapeshellcmd(Files::getUnixStylePath($settings['core']['phpBinaryPathAndFilename'])) . '"';
             } else {
                 $phpBinaryPathAndFilename = escapeshellarg(Files::getUnixStylePath($settings['core']['phpBinaryPathAndFilename']));
             }
-            $command = sprintf('%s -c %s -v', $phpBinaryPathAndFilename, escapeshellarg(php_ini_loaded_file()));
+            $iniPath = php_ini_loaded_file();
+            if ($iniPath === false) {
+                throw new \Exception('Failed to resolve PHP ini path', 1744460978);
+            }
+            $command = sprintf('%s -c %s -v', $phpBinaryPathAndFilename, escapeshellarg($iniPath));
             exec($command, $output, $result);
             if ($result !== 0) {
                 if (!file_exists($phpBinaryPathAndFilename)) {
@@ -452,7 +490,7 @@ public static function recompileClasses(Bootstrap $bootstrap)
      *
      * @param Bootstrap $bootstrap
      */
-    public static function initializeObjectManagerCompileTimeCreate(Bootstrap $bootstrap)
+    public static function initializeObjectManagerCompileTimeCreate(Bootstrap $bootstrap): void
     {
         $objectManager = new CompileTimeObjectManager($bootstrap->getContext());
         $bootstrap->setEarlyInstance(ObjectManagerInterface::class, $objectManager);
@@ -475,7 +513,7 @@ public static function initializeObjectManagerCompileTimeCreate(Bootstrap $boots
      */
     public static function initializeObjectManagerCompileTimeFinalize(Bootstrap $bootstrap)
     {
-        /** @var CompileTimeObjectManager $objectManager */
+        /** @var CompileTimeObjectManager $objectManager @phpstan-ignore missingType.generics */
         $objectManager = $bootstrap->getObjectManager();
         $configurationManager = $bootstrap->getEarlyInstance(ConfigurationManager::class);
         $reflectionService = $objectManager->get(ReflectionService::class);
@@ -486,7 +524,11 @@ public static function initializeObjectManagerCompileTimeFinalize(Bootstrap $boo
         $objectManager->injectAllSettings($configurationManager->getConfiguration(ConfigurationManager::CONFIGURATION_TYPE_SETTINGS));
         $objectManager->injectReflectionService($reflectionService);
         $objectManager->injectConfigurationManager($configurationManager);
-        $objectManager->injectConfigurationCache($cacheManager->getCache('Flow_Object_Configuration'));
+        $configurationCache = $cacheManager->getCache('Flow_Object_Configuration');
+        if (!$configurationCache instanceof VariableFrontend) {
+            throw new \Exception('Configuration cache must be of type VariableFrontend', 1744459785);
+        }
+        $objectManager->injectConfigurationCache($configurationCache);
         $objectManager->injectLogger($logger);
         $objectManager->initialize($packageManager->getAvailablePackages());
 
@@ -543,7 +585,7 @@ public static function initializeReflectionServiceFactory(Bootstrap $bootstrap)
      * @param Bootstrap $bootstrap
      * @throws FlowException
      */
-    public static function initializeReflectionService(Bootstrap $bootstrap)
+    public static function initializeReflectionService(Bootstrap $bootstrap): void
     {
         $reflectionService = $bootstrap->getEarlyInstance(ReflectionServiceFactory::class)->create();
         $bootstrap->setEarlyInstance(ReflectionService::class, $reflectionService);
@@ -607,12 +649,12 @@ public static function initializeSystemFileMonitor(Bootstrap $bootstrap)
 
     /**
      * @param Bootstrap $bootstrap
-     * @return array
+     * @return array<mixed>
      */
     protected static function getListOfPackagesWithConfiguredObjects(Bootstrap $bootstrap): array
     {
         $objectManager = $bootstrap->getObjectManager();
-        /** @phpstan-ignore-next-line the object manager interface doesn't specify this method */
+        /** @phpstan-ignore method.notFound (not part of the interface) */
         $allObjectConfigurations = $objectManager->getAllObjectConfigurations();
         $packagesWithConfiguredObjects = array_reduce($allObjectConfigurations, function ($foundPackages, $item) {
             if (isset($item['p']) && !in_array($item['p'], $foundPackages)) {
@@ -683,9 +725,17 @@ public static function initializeResources(Bootstrap $bootstrap)
      * Executes the given command as a sub-request to the Flow CLI system.
      *
      * @param string $commandIdentifier E.g. neos.flow:cache:flush
-     * @param array $settings The Neos.Flow settings
+     * @param array{
+     *       core: array{
+     *           context: string,
+     *           phpBinaryPathAndFilename: string,
+     *           subRequestPhpIniPathAndFilename?: mixed,
+     *           subRequestEnvironmentVariables?: array<mixed>,
+     *           subRequestIniEntries?: array<mixed>,
+     *       },
+     *   } $settings The Neos.Flow settings
      * @param boolean $outputResults Echo the commands output on success
-     * @param array $commandArguments Command arguments
+     * @param array<mixed> $commandArguments Command arguments
      * @return true Legacy return value. Will always be true. A failure is expressed as a thrown exception
      * @throws Exception\SubProcessException The execution of the sub process failed
      * @api
@@ -712,7 +762,7 @@ public static function executeCommand(string $commandIdentifier, array $settings
                 }
                 if (file_exists(FLOW_PATH_DATA . 'Logs/Exceptions') && is_dir(FLOW_PATH_DATA . 'Logs/Exceptions') && is_writable(FLOW_PATH_DATA . 'Logs/Exceptions')) {
                     // Logs the command string `php ./flow foo:bar` inside `Logs/Exceptions/123-command.txt`
-                    $referenceCode = date('YmdHis', $_SERVER['REQUEST_TIME']) . substr(md5(rand()), 0, 6);
+                    $referenceCode = date('YmdHis', $_SERVER['REQUEST_TIME']) . substr(md5((string)rand()), 0, 6);
                     $errorDumpPathAndFilename = FLOW_PATH_DATA . 'Logs/Exceptions/' . $referenceCode . '-command.txt';
                     file_put_contents($errorDumpPathAndFilename, $command);
                     $exceptionMessage .= sprintf(' It has been stored in: %s', basename($errorDumpPathAndFilename));
@@ -735,8 +785,16 @@ public static function executeCommand(string $commandIdentifier, array $settings
      * Note: As the command execution is done in a separate thread potential exceptions or failures will *not* be reported
      *
      * @param string $commandIdentifier E.g. neos.flow:cache:flush
-     * @param array $settings The Neos.Flow settings
-     * @param array $commandArguments Command arguments
+     * @param array{
+     *       core: array{
+     *           context: string,
+     *           phpBinaryPathAndFilename: string,
+     *           subRequestPhpIniPathAndFilename?: mixed,
+     *           subRequestEnvironmentVariables?: array<mixed>,
+     *           subRequestIniEntries?: array<mixed>,
+     *       },
+     *   } $settings The Neos.Flow settings
+     * @param array<mixed> $commandArguments Command arguments
      * @return void
      * @api
      */
@@ -746,14 +804,25 @@ public static function executeCommandAsync(string $commandIdentifier, array $set
         if (DIRECTORY_SEPARATOR === '/') {
             exec($command . ' > /dev/null 2>/dev/null &');
         } else {
-            pclose(popen('START /B CMD /S /C "' . $command . '" > NUL 2> NUL &', 'r'));
+            $handle = popen('START /B CMD /S /C "' . $command . '" > NUL 2> NUL &', 'r');
+            if ($handle) {
+                pclose($handle);
+            }
         }
     }
 
     /**
      * @param string $commandIdentifier E.g. neos.flow:cache:flush
-     * @param array $settings The Neos.Flow settings
-     * @param array $commandArguments Command arguments
+     * @param array{
+     *      core: array{
+     *          context: string,
+     *          phpBinaryPathAndFilename: string,
+     *          subRequestPhpIniPathAndFilename?: mixed,
+     *          subRequestEnvironmentVariables?: array<mixed>,
+     *          subRequestIniEntries?: mixed,
+     *      },
+     *  } $settings The Neos.Flow settings
+     * @param array<mixed> $commandArguments Command arguments
      * @return string A command line command ready for being exec()uted
      */
     protected static function buildSubprocessCommand(string $commandIdentifier, array $settings, array $commandArguments = []): string
@@ -781,7 +850,14 @@ protected static function buildSubprocessCommand(string $commandIdentifier, arra
     }
 
     /**
-     * @param array $settings The Neos.Flow settings
+     * @param array{
+     *     core: array{
+     *         context: string,
+     *         phpBinaryPathAndFilename: string,
+     *         subRequestPhpIniPathAndFilename?: mixed,
+     *         subRequestEnvironmentVariables?: array<mixed>,
+     *     },
+     * } $settings The Neos.Flow settings
      * @return string A command line command for PHP, which can be extended and then exec()uted
      * @throws Exception\SubProcessException in case the phpBinaryPathAndFilename is incorrect
      */
@@ -823,6 +899,9 @@ public static function buildPhpCommand(array $settings): string
             } else {
                 $useIniFile = $settings['core']['subRequestPhpIniPathAndFilename'];
             }
+            if (!is_string($useIniFile)) {
+                throw new \Exception('Could not resolve ini file', 1744460624);
+            }
             $command .= ' -c ' . escapeshellarg($useIniFile);
         }
 
@@ -838,7 +917,7 @@ public static function buildPhpCommand(array $settings): string
      * @param string $phpBinaryPathAndFilename
      * @throws Exception\SubProcessException in case the php binary doesn't exist / is a different one for the current cli request
      */
-    protected static function ensureCLISubrequestsUseCurrentlyRunningPhpBinary($phpBinaryPathAndFilename)
+    protected static function ensureCLISubrequestsUseCurrentlyRunningPhpBinary($phpBinaryPathAndFilename): void
     {
         // Do nothing for non-CLI requests
         if (PHP_SAPI !== 'cli') {
@@ -846,7 +925,7 @@ protected static function ensureCLISubrequestsUseCurrentlyRunningPhpBinary($phpB
         }
 
         // Ensure the actual PHP binary is known before checking if it is correct.
-        if (!$phpBinaryPathAndFilename || strlen($phpBinaryPathAndFilename) === 0) {
+        if (!$phpBinaryPathAndFilename) {
             throw new Exception\SubProcessException('"Neos.Flow.core.phpBinaryPathAndFilename" is not set.', 1689676816060);
         }
 
@@ -915,7 +994,7 @@ protected static function ensureCLISubrequestsUseCurrentlyRunningPhpBinary($phpB
      * @param string $phpCommand the completely build php string that is used to execute subrequests
      * @throws Exception\SubProcessException in case the php binary doesn't exist, or is not suitable for cli usage, or its version doesn't match
      */
-    protected static function ensureWebSubrequestsUseCurrentlyRunningPhpVersion($phpCommand)
+    protected static function ensureWebSubrequestsUseCurrentlyRunningPhpVersion($phpCommand): void
     {
         // Do nothing for CLI requests
         if (PHP_SAPI === 'cli') {
diff --git a/Neos.Flow/Classes/Core/Booting/Sequence.php b/Neos.Flow/Classes/Core/Booting/Sequence.php
index 99999e236b..fd325adcea 100644
--- a/Neos.Flow/Classes/Core/Booting/Sequence.php
+++ b/Neos.Flow/Classes/Core/Booting/Sequence.php
@@ -28,7 +28,7 @@ class Sequence
     protected $identifier;
 
     /**
-     * @var array
+     * @var array<string,array<int|string,Step>>
      */
     protected $steps = [];
 
diff --git a/Neos.Flow/Classes/Core/Bootstrap.php b/Neos.Flow/Classes/Core/Bootstrap.php
index 5d1848d51b..9eddf0b8f6 100644
--- a/Neos.Flow/Classes/Core/Bootstrap.php
+++ b/Neos.Flow/Classes/Core/Bootstrap.php
@@ -57,7 +57,7 @@ class Bootstrap
     /**
      * The same instance like $objectManager, but static, for use in the proxy classes.
      *
-     * @var ObjectManagerInterface
+     * @var ?ObjectManagerInterface
      */
     public static $staticObjectManager;
 
@@ -164,7 +164,7 @@ public function registerRequestHandler(RequestHandlerInterface $requestHandler)
      *
      * @param class-string<RequestHandlerInterface> $className
      */
-    public function setPreselectedRequestHandlerClassName(string $className)
+    public function setPreselectedRequestHandlerClassName(string $className): void
     {
         $this->preselectedRequestHandlerClassName = $className;
     }
@@ -492,9 +492,21 @@ protected function defineConstants()
                 }
             }
             if ($rootPath !== false) {
-                $rootPath = Files::getUnixStylePath(realpath($rootPath)) . '/';
-                $testPath = Files::getUnixStylePath(realpath(Files::concatenatePaths([$rootPath, 'Packages/Framework/Neos.Flow']))) . '/';
-                $expectedPath = Files::getUnixStylePath(realpath(FLOW_PATH_FLOW)) . '/';
+                $realRootPath = realpath($rootPath);
+                if ($realRootPath === false) {
+                    throw new \RuntimeException('Failed to resolve real root path', 1744459165);
+                }
+                $rootPath = Files::getUnixStylePath($realRootPath) . '/';
+                $realTestPath = realpath(Files::concatenatePaths([$rootPath, 'Packages/Framework/Neos.Flow']));
+                if ($realTestPath === false) {
+                    throw new \RuntimeException('Failed to resolve real test path', 1744459220);
+                }
+                $testPath = Files::getUnixStylePath($realTestPath) . '/';
+                $realExpectedPath = realpath(FLOW_PATH_FLOW);
+                if ($realExpectedPath === false) {
+                    throw new \RuntimeException('Failed to resolve real expected path', 1744459246);
+                }
+                $expectedPath = Files::getUnixStylePath($realExpectedPath) . '/';
                 if ($testPath !== $expectedPath) {
                     echo('Flow: Invalid root path. (Error #1248964375)' . PHP_EOL . '"' . $testPath . '" does not lead to' . PHP_EOL . '"' . $expectedPath . '"' . PHP_EOL);
                     http_response_code(500);
@@ -513,16 +525,28 @@ protected function defineConstants()
             }
             if (!defined('FLOW_PATH_WEB')) {
                 if (isset($_SERVER['FLOW_WEBPATH']) && is_dir($_SERVER['FLOW_WEBPATH'])) {
-                    define('FLOW_PATH_WEB', Files::getUnixStylePath(realpath($_SERVER['FLOW_WEBPATH'])) . '/');
+                    $webPath = realpath($_SERVER['FLOW_WEBPATH']);
+                    if ($webPath === false) {
+                        throw new \RuntimeException('Failed to resolve web path', 1744459038);
+                    }
+                    define('FLOW_PATH_WEB', Files::getUnixStylePath($webPath) . '/');
                 } else {
                     define('FLOW_PATH_WEB', FLOW_PATH_ROOT . 'Web/');
                 }
             }
         } else {
             if (!defined('FLOW_PATH_ROOT')) {
-                define('FLOW_PATH_ROOT', Files::getUnixStylePath(realpath(dirname($_SERVER['SCRIPT_FILENAME']) . '/../')) . '/');
+                $rootPath = realpath(dirname($_SERVER['SCRIPT_FILENAME']) . '/../');
+                if ($rootPath === false) {
+                    throw new \RuntimeException('Failed to resolve root path', 1744459011);
+                }
+                define('FLOW_PATH_ROOT', Files::getUnixStylePath($rootPath) . '/');
+            }
+            $webPath = realpath(dirname($_SERVER['SCRIPT_FILENAME']));
+            if ($webPath === false) {
+                throw new \RuntimeException('Failed to resolve web path', 1744459038);
             }
-            define('FLOW_PATH_WEB', Files::getUnixStylePath(realpath(dirname($_SERVER['SCRIPT_FILENAME']))) . '/');
+            define('FLOW_PATH_WEB', Files::getUnixStylePath($webPath) . '/');
         }
 
         define('FLOW_PATH_CONFIGURATION', FLOW_PATH_ROOT . 'Configuration/');
diff --git a/Neos.Flow/Classes/Core/ClassLoader.php b/Neos.Flow/Classes/Core/ClassLoader.php
index c936b2b759..f827a21591 100644
--- a/Neos.Flow/Classes/Core/ClassLoader.php
+++ b/Neos.Flow/Classes/Core/ClassLoader.php
@@ -12,7 +12,7 @@
  */
 
 use Neos\Flow\Annotations as Flow;
-use Neos\Flow\Package;
+use Neos\Flow\Package\PackageInterface;
 use Neos\Utility\Files;
 
 /**
@@ -46,7 +46,7 @@ class ClassLoader
     /**
      * A list of namespaces this class loader is definitely responsible for.
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $packageNamespaces = [];
 
@@ -56,7 +56,7 @@ class ClassLoader
     protected $considerTestsNamespace = false;
 
     /**
-     * @var array
+     * @var array<string,true>
      */
     protected $ignoredClassNames = [
         'integer' => true,
@@ -78,7 +78,7 @@ class ClassLoader
     ];
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $fallbackClassPaths = [];
 
@@ -87,13 +87,13 @@ class ClassLoader
      * to save time in resolving those non existent classes.
      * Usually these will be annotations that have no class.
      *
-     * @var array
+     * @var array<string,true>
      *
      */
     protected $nonExistentClasses = [];
 
     /**
-     * @param array $defaultPackageEntries Adds default entries for packages that should be available for very early loading
+     * @param array<array{namespace: string, classPath: string, mappingType: string}> $defaultPackageEntries Adds default entries for packages that should be available for very early loading
      */
     public function __construct(array $defaultPackageEntries = [])
     {
@@ -161,8 +161,8 @@ public function loadClass(string $className): bool
      * there may exist a package "Neos" and a package "Neos.NodeTypes" -- so a class Neos\NodeTypes\Foo must be first
      * loaded (if it exists) from Neos.NodeTypes, falling back to Neos afterwards.
      *
-     * @param array $possiblePaths
-     * @param array $namespaceParts
+     * @param array<mixed> $possiblePaths
+     * @param array<string> $namespaceParts
      * @param integer $packageNamespacePartCount
      * @return boolean
      */
@@ -191,13 +191,13 @@ protected function loadClassFromPossiblePaths(array $possiblePaths, array $names
     /**
      * Sets the available packages
      *
-     * @param array $activePackages An array of \Neos\Flow\Package\Package objects
+     * @param array<PackageInterface> $activePackages
      * @return void
      */
     public function setPackages(array $activePackages)
     {
-        /** @var Package $package */
-        foreach ($activePackages as $packageKey => $package) {
+        foreach ($activePackages as $package) {
+            /** @phpstan-ignore method.notFound (not part of the interface) */
             foreach ($package->getFlattenedAutoloadConfiguration() as $configuration) {
                 $this->createNamespaceMapEntry($configuration['namespace'], $configuration['classPath'], $configuration['mappingType']);
             }
@@ -292,7 +292,7 @@ protected function removeNamespaceMapEntry(string $namespace, string $classPath,
     /**
      * Try to build a path to a class according to PSR-0 rules.
      *
-     * @param array $classNameParts Parts of the FQ classname.
+     * @param array<string> $classNameParts Parts of the FQ classname.
      * @param string $classPath Already detected class path to a possible package.
      * @return string
      */
@@ -306,7 +306,7 @@ protected function buildClassPathWithPsr0(array $classNameParts, string $classPa
     /**
      * Try to build a path to a class according to PSR-4 rules.
      *
-     * @param array $classNameParts Parts of the FQ classname.
+     * @param array<string> $classNameParts Parts of the FQ classname.
      * @param string $classPath Already detected class path to a possible package.
      * @param integer $packageNamespacePartCount Amount of parts of the className that is also part of the package namespace.
      * @return string
diff --git a/Neos.Flow/Classes/Core/LockManager.php b/Neos.Flow/Classes/Core/LockManager.php
index 26d228fbb5..dce2fd830d 100644
--- a/Neos.Flow/Classes/Core/LockManager.php
+++ b/Neos.Flow/Classes/Core/LockManager.php
@@ -47,7 +47,7 @@ class LockManager
     protected $lockHoldingPage;
 
     /**
-     * @var resource
+     * @var resource|null
      */
     protected $lockResource;
 
@@ -128,8 +128,8 @@ public function exitIfSiteLocked()
     public function lockSiteOrExit()
     {
         touch($this->lockFlagPathAndFilename);
-        $this->lockResource = fopen($this->lockPathAndFilename, 'w+');
-        if (!flock($this->lockResource, LOCK_EX | LOCK_NB)) {
+        $this->lockResource = fopen($this->lockPathAndFilename, 'w+') ?: null;
+        if ($this->lockResource && !flock($this->lockResource, LOCK_EX | LOCK_NB)) {
             fclose($this->lockResource);
             $this->doExit();
         }
@@ -168,6 +168,7 @@ public function unlockSite()
      */
     protected function doExit()
     {
+        /** @phpstan-ignore identical.alwaysFalse (can also be "Web") */
         if (FLOW_SAPITYPE === 'Web') {
             header('HTTP/1.1 503 Service Temporarily Unavailable');
             readfile($this->lockHoldingPage);
diff --git a/Neos.Flow/Classes/Core/ProxyClassLoader.php b/Neos.Flow/Classes/Core/ProxyClassLoader.php
index 350b642ba9..9cf114c8e0 100644
--- a/Neos.Flow/Classes/Core/ProxyClassLoader.php
+++ b/Neos.Flow/Classes/Core/ProxyClassLoader.php
@@ -25,7 +25,7 @@
 class ProxyClassLoader
 {
     /**
-     * @var array
+     * @var array<string,true>
      */
     protected $ignoredClassNames = [
         'integer' => true,
@@ -52,7 +52,7 @@ class ProxyClassLoader
     protected $classesCache;
 
     /**
-     * @var array
+     * @var ?array<mixed>
      */
     protected $availableProxyClasses;
 
diff --git a/Neos.Flow/Classes/Error/AbstractExceptionHandler.php b/Neos.Flow/Classes/Error/AbstractExceptionHandler.php
index 1e753eb284..7c586361d2 100644
--- a/Neos.Flow/Classes/Error/AbstractExceptionHandler.php
+++ b/Neos.Flow/Classes/Error/AbstractExceptionHandler.php
@@ -32,17 +32,17 @@
 abstract class AbstractExceptionHandler implements ExceptionHandlerInterface
 {
     /**
-     * @var LoggerInterface
+     * @var ?LoggerInterface
      */
     protected $logger;
 
     /**
-     * @var ThrowableStorageInterface
+     * @var ?ThrowableStorageInterface
      */
     protected $throwableStorage;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $options = [];
 
@@ -51,11 +51,11 @@ abstract class AbstractExceptionHandler implements ExceptionHandlerInterface
      *
      * @var array{
      *      viewClassName: string,
-     *      viewOptions: array,
+     *      viewOptions: array<mixed>,
      *      renderTechnicalDetails: bool,
-     *      logException: bool,
+     *      logException?: bool,
      *      renderingGroup?: string,
-     *      variables?: array
+     *      variables?: array<mixed>
      * }
      */
     protected $renderingOptions;
@@ -65,7 +65,7 @@ abstract class AbstractExceptionHandler implements ExceptionHandlerInterface
      * @return void
      * @Flow\Autowiring(enabled=false)
      */
-    public function injectLogger(LoggerInterface $logger)
+    public function injectLogger(LoggerInterface $logger): void
     {
         $this->logger = $logger;
     }
@@ -73,7 +73,7 @@ public function injectLogger(LoggerInterface $logger)
     /**
      * @param ThrowableStorageInterface $throwableStorage
      */
-    public function injectThrowableStorage(ThrowableStorageInterface $throwableStorage)
+    public function injectThrowableStorage(ThrowableStorageInterface $throwableStorage): void
     {
         $this->throwableStorage = $throwableStorage;
     }
@@ -81,7 +81,7 @@ public function injectThrowableStorage(ThrowableStorageInterface $throwableStora
     /**
      * Sets options of this exception handler.
      *
-     * @param array $options Options for the exception handler
+     * @param array<mixed> $options Options for the exception handler
      * @return void
      */
     public function setOptions(array $options)
@@ -117,7 +117,7 @@ public function handleException($exception)
         $exceptionWasLogged = false;
         if ($this->throwableStorage instanceof ThrowableStorageInterface && isset($this->renderingOptions['logException']) && $this->renderingOptions['logException']) {
             $message = $this->throwableStorage->logThrowable($exception);
-            $this->logger->critical($message);
+            $this->logger?->critical($message);
             $exceptionWasLogged = true;
         }
 
@@ -141,7 +141,7 @@ abstract protected function echoExceptionWeb($exception);
      * Prepares a view for rendering the custom error page.
      *
      * @param \Throwable $exception
-     * @param array $renderingOptions Rendering options as defined in the settings
+     * @param array<string,mixed> $renderingOptions Rendering options as defined in the settings
      * @return ViewInterface
      */
     protected function buildView(\Throwable $exception, array $renderingOptions): ViewInterface
@@ -190,7 +190,14 @@ protected function buildView(\Throwable $exception, array $renderingOptions): Vi
      * Checks if custom rendering rules apply to the given $exception and returns those.
      *
      * @param \Throwable $exception
-     * @return array the custom rendering options, or the default
+     * @return array{
+     *       viewClassName: string,
+     *       viewOptions: array<mixed>,
+     *       renderTechnicalDetails: bool,
+     *       logException?: bool,
+     *       renderingGroup?: string,
+     *       variables?: array<mixed>
+     *  } the custom rendering options, or the default
      */
     protected function resolveCustomRenderingOptions(\Throwable $exception): array
     {
@@ -309,7 +316,7 @@ protected function renderSingleExceptionCli(\Throwable $exception): string
             $exceptionMessage .= $this->renderExceptionDetailCli('Code', $exception->getCode());
         }
         $exceptionMessage .= $this->renderExceptionDetailCli('File', str_replace(FLOW_PATH_ROOT, '', $exception->getFile()));
-        $exceptionMessage .= $this->renderExceptionDetailCli('Line', $exception->getLine());
+        $exceptionMessage .= $this->renderExceptionDetailCli('Line', (string)$exception->getLine());
 
         return $exceptionMessage;
     }
@@ -336,7 +343,7 @@ protected function renderExceptionDetailCli(string $label, string $value): strin
      * - Otherwise the subject is everything until the first line break or end of sentence, the body contains the rest
      *
      * @param string $exceptionMessage
-     * @return array in the format array('subject' => '<subject>', 'body' => '<body>');
+     * @return array{subject: string, body: string}
      */
     protected function splitExceptionMessage(string $exceptionMessage): array
     {
diff --git a/Neos.Flow/Classes/Error/Debugger.php b/Neos.Flow/Classes/Error/Debugger.php
index de53c73e42..a0aadef08a 100644
--- a/Neos.Flow/Classes/Error/Debugger.php
+++ b/Neos.Flow/Classes/Error/Debugger.php
@@ -27,13 +27,13 @@
 class Debugger
 {
     /**
-     * @var ObjectManagerInterface
+     * @var ?ObjectManagerInterface
      */
     protected static $objectManager;
 
     /**
      *
-     * @var array
+     * @var array<mixed>
      */
     protected static $renderedObjects = [];
 
@@ -41,7 +41,7 @@ class Debugger
      * Hardcoded list of Flow class names (regex) which should not be displayed during debugging.
      * This is a fallback in case the classes could not be fetched from the configuration
      *
-     * @var array
+     * @var array<string,true>
      */
     protected static $ignoredClassesFallback = [
         'Neos\\\\Flow\\\\Aop.*' => true,
@@ -138,7 +138,7 @@ public static function renderDump($variable, int $level, bool $plaintext = false
                 $dump = sprintf('\'<span class="debug-string">%s</span>\' (%s)', htmlspecialchars($croppedValue), strlen($variable));
             }
         } elseif (is_numeric($variable)) {
-            $dump = sprintf('%s %s', gettype($variable), self::ansiEscapeWrap($variable, '35', $ansiColors));
+            $dump = sprintf('%s %s', gettype($variable), self::ansiEscapeWrap((string)$variable, '35', $ansiColors));
         } elseif (is_iterable($variable)) {
             $dump = self::renderArrayDump($variable, $level + 1, $plaintext, $ansiColors);
         } elseif (is_object($variable)) {
@@ -157,7 +157,7 @@ public static function renderDump($variable, int $level, bool $plaintext = false
     /**
      * Renders a dump of the given array
      *
-     * @param iterable $array
+     * @param iterable<mixed> $array
      * @param integer $level
      * @param boolean $plaintext
      * @param boolean $ansiColors
@@ -320,7 +320,7 @@ protected static function renderObjectDump($object, int $level, bool $renderProp
     /**
      * Renders some backtrace
      *
-     * @param array $trace The trace
+     * @param array<int,array<string,mixed>> $trace The trace
      * @param boolean $includeCode Include code snippet
      * @param boolean $plaintext
      * @return string Backtrace information
@@ -393,7 +393,7 @@ protected static function renderCallArgumentsHtml(array $callArguments): string
     }
 
     /**
-     * @param array $trace
+     * @param array<int,array<string,mixed>> $trace
      * @param bool $includeCode
      * @return string
      */
@@ -547,7 +547,7 @@ protected static function getCodeSnippetPlaintext(string $filePathAndName, int $
 
     /**
      * @param string $file
-     * @return array
+     * @return array{short: string, proxy: string}
      */
     public static function findProxyAndShortFilePath(string $file): array
     {
@@ -556,7 +556,9 @@ public static function findProxyAndShortFilePath(string $file): array
         $proxyClassPathPosition = strpos($file, 'Flow_Object_Classes/');
         if ($proxyClassPathPosition && is_file($file)) {
             $fileContent = @file($file);
-            $originalPath = trim(substr($fileContent[count($fileContent) - 2], 19));
+            if ($fileContent !== false) {
+                $originalPath = trim(substr($fileContent[count($fileContent) - 2], 19));
+            }
         }
 
         $originalPath = str_replace($flowRoot, '', $originalPath);
@@ -603,11 +605,9 @@ public static function getIgnoredClassesRegex(): string
 
         if (self::$objectManager instanceof ObjectManagerInterface) {
             $configurationManager = self::$objectManager->get(ConfigurationManager::class);
-            if ($configurationManager instanceof ConfigurationManager) {
-                $ignoredClassesFromSettings = $configurationManager->getConfiguration('Settings', 'Neos.Flow.error.debugger.ignoredClasses');
-                if (is_array($ignoredClassesFromSettings)) {
-                    $ignoredClassesConfiguration = Arrays::arrayMergeRecursiveOverrule($ignoredClassesConfiguration, $ignoredClassesFromSettings);
-                }
+            $ignoredClassesFromSettings = $configurationManager->getConfiguration('Settings', 'Neos.Flow.error.debugger.ignoredClasses');
+            if (is_array($ignoredClassesFromSettings)) {
+                $ignoredClassesConfiguration = Arrays::arrayMergeRecursiveOverrule($ignoredClassesConfiguration, $ignoredClassesFromSettings);
             }
         }
 
@@ -639,11 +639,9 @@ public static function getRecursionLimit(): int
 
         if (self::$objectManager instanceof ObjectManagerInterface) {
             $configurationManager = self::$objectManager->get(ConfigurationManager::class);
-            if ($configurationManager instanceof ConfigurationManager) {
-                $recursionLimitFromSettings = $configurationManager->getConfiguration('Settings', 'Neos.Flow.error.debugger.recursionLimit');
-                if (is_int($recursionLimitFromSettings)) {
-                    self::$recursionLimit = $recursionLimitFromSettings;
-                }
+            $recursionLimitFromSettings = $configurationManager->getConfiguration('Settings', 'Neos.Flow.error.debugger.recursionLimit');
+            if (is_int($recursionLimitFromSettings)) {
+                self::$recursionLimit = $recursionLimitFromSettings;
             }
         }
 
@@ -668,7 +666,9 @@ public static function getRecursionLimit(): int
 function var_dump($variable, ?string $title = null, bool $return = false, ?bool $plaintext = null)
 {
     if ($plaintext === null) {
+        /** @phpstan-ignore identical.alwaysTrue (FLOW_SAPITYPE can also be "Web") */
         $plaintext = (FLOW_SAPITYPE === 'CLI');
+        /** @phpstan-ignore booleanAnd.leftAlwaysTrue (no, this can be false) */
         $ansiColors = $plaintext && DIRECTORY_SEPARATOR === '/';
     } else {
         $ansiColors = false;
diff --git a/Neos.Flow/Classes/Error/ErrorHandler.php b/Neos.Flow/Classes/Error/ErrorHandler.php
index 1bb8b32eb1..fb7005f582 100644
--- a/Neos.Flow/Classes/Error/ErrorHandler.php
+++ b/Neos.Flow/Classes/Error/ErrorHandler.php
@@ -22,7 +22,7 @@
 class ErrorHandler
 {
     /**
-     * @var array
+     * @var array<int>
      */
     protected $exceptionalErrors = [];
 
@@ -32,13 +32,15 @@ class ErrorHandler
      */
     public function __construct()
     {
-        set_error_handler([$this, 'handleError']);
+        /** @var callable $callback */
+        $callback = [$this, 'handleError'];
+        set_error_handler($callback);
     }
 
     /**
      * Defines which error levels result should result in an exception thrown.
      *
-     * @param array $exceptionalErrors An array of E_* error levels
+     * @param array<int> $exceptionalErrors An array of E_* error levels
      * @return void
      */
     public function setExceptionalErrors(array $exceptionalErrors)
diff --git a/Neos.Flow/Classes/Error/ExceptionHandlerInterface.php b/Neos.Flow/Classes/Error/ExceptionHandlerInterface.php
index ce8faeff9c..f1d1005b1c 100644
--- a/Neos.Flow/Classes/Error/ExceptionHandlerInterface.php
+++ b/Neos.Flow/Classes/Error/ExceptionHandlerInterface.php
@@ -27,7 +27,7 @@ public function handleException($exception);
     /**
      * Sets options of this exception handler
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      * @return void
      */
     public function setOptions(array $options);
diff --git a/Neos.Flow/Classes/Error/ProductionExceptionHandler.php b/Neos.Flow/Classes/Error/ProductionExceptionHandler.php
index a637f90e0e..a629a31997 100644
--- a/Neos.Flow/Classes/Error/ProductionExceptionHandler.php
+++ b/Neos.Flow/Classes/Error/ProductionExceptionHandler.php
@@ -56,8 +56,10 @@ protected function echoExceptionWeb($exception)
                 echo $this->renderStatically($statusCode, $referenceCode);
             }
         } catch (\Exception $innerException) {
-            $message = $this->throwableStorage->logThrowable($innerException);
-            $this->logger->critical($message);
+            $message = $this->throwableStorage?->logThrowable($innerException);
+            if ($message) {
+                $this->logger?->critical($message);
+            }
         }
     }
 
diff --git a/Neos.Flow/Classes/Exception.php b/Neos.Flow/Classes/Exception.php
index 0029184a32..7cdfc97152 100644
--- a/Neos.Flow/Classes/Exception.php
+++ b/Neos.Flow/Classes/Exception.php
@@ -22,7 +22,7 @@
 class Exception extends \Exception implements WithReferenceCodeInterface, WithHttpStatusInterface
 {
     /**
-     * @var string
+     * @var ?string
      */
     protected $referenceCode;
 
@@ -41,7 +41,7 @@ class Exception extends \Exception implements WithReferenceCodeInterface, WithHt
     public function getReferenceCode()
     {
         if (!isset($this->referenceCode)) {
-            $this->referenceCode = date('YmdHis', $_SERVER['REQUEST_TIME']) . substr(md5(rand()), 0, 6);
+            $this->referenceCode = date('YmdHis', $_SERVER['REQUEST_TIME']) . substr(md5((string)rand()), 0, 6);
         }
         return $this->referenceCode;
     }
diff --git a/Neos.Flow/Classes/Http/CacheControlDirectives.php b/Neos.Flow/Classes/Http/CacheControlDirectives.php
index 4c6bda2bd3..f3fefe8544 100644
--- a/Neos.Flow/Classes/Http/CacheControlDirectives.php
+++ b/Neos.Flow/Classes/Http/CacheControlDirectives.php
@@ -19,7 +19,7 @@
 class CacheControlDirectives
 {
     /**
-     * @var array
+     * @var array<string,string>
      */
     protected $cacheDirectives = [
         'visibility' => '',
@@ -170,7 +170,7 @@ public function getDirective(string $name)
     }
 
     /**
-     * @return array
+     * @return array<int,string>
      */
     public function getDirectives(): array
     {
diff --git a/Neos.Flow/Classes/Http/Client/Browser.php b/Neos.Flow/Classes/Http/Client/Browser.php
index 50c1112480..f71b854c20 100644
--- a/Neos.Flow/Classes/Http/Client/Browser.php
+++ b/Neos.Flow/Classes/Http/Client/Browser.php
@@ -62,7 +62,7 @@ class Browser implements ClientInterface
      * A simple string array that keeps track of occurred "Location" header
      * redirections to avoid infinite loops if the same redirection happens
      *
-     * @var array
+     * @var array<int,string>
      */
     protected $redirectionStack = [];
 
@@ -112,7 +112,7 @@ public function setRequestEngine(RequestEngineInterface $requestEngine)
      * Allows to add headers to be sent with every request the browser executes.
      *
      * @param string $name Name of the header, for example "Location", "Content-Description" etc.
-     * @param array|string|\DateTime $values An array of values or a single value for the specified header field
+     * @param array<mixed>|string|\DateTime|\DateTimeImmutable $values An array of values or a single value for the specified header field
      * @return void
      * @see Message::setHeader()
      */
@@ -139,23 +139,20 @@ public function removeAutomaticRequestHeader($name)
      *
      * @param string|UriInterface $uri
      * @param string $method Request method, for example "GET"
-     * @param array $arguments Arguments to send in the request body
+     * @param array<mixed> $arguments Arguments to send in the request body
      * @param UploadedFileInterface[]|mixed[][] $files A (deep) array of UploadedFile or an untangled $_FILES array
-     * @param array $server
+     * @param array<mixed> $server
      * @param string $content
      * @return ResponseInterface The HTTP response
      * @throws \InvalidArgumentException
      * @throws InfiniteRedirectionException
      * @api
      */
-    public function request($uri, $method = 'GET', array $arguments = [], array $files = [], array $server = [], $content = null): ResponseInterface
+    public function request(string|UriInterface $uri, $method = 'GET', array $arguments = [], array $files = [], array $server = [], $content = null): ResponseInterface
     {
         if (is_string($uri)) {
             $uri = new Uri($uri);
         }
-        if (!$uri instanceof UriInterface) {
-            throw new \InvalidArgumentException('$uri must be a URI object or a valid string representation of a URI.', 1333443624);
-        }
         $request = $this->serverRequestFactory->createServerRequest($method, $uri, $server);
         if ($content) {
             $request = $request->withBody($this->contentStreamFactory->createStream($content));
diff --git a/Neos.Flow/Classes/Http/Client/CurlEngine.php b/Neos.Flow/Classes/Http/Client/CurlEngine.php
index f831902812..5b82b3903b 100644
--- a/Neos.Flow/Classes/Http/Client/CurlEngine.php
+++ b/Neos.Flow/Classes/Http/Client/CurlEngine.php
@@ -25,7 +25,7 @@
 class CurlEngine implements RequestEngineInterface
 {
     /**
-     * @var array
+     * @var array<int,mixed>
      */
     protected $options = [
         CURLOPT_RETURNTRANSFER => true,
@@ -42,9 +42,9 @@ class CurlEngine implements RequestEngineInterface
      *
      * @param integer $optionName One of the CURLOPT_* constants
      * @param mixed $value The value to set
-     * @throws \InvalidArgumentException
+     * @throws InvalidArgumentException
      */
-    public function setOption($optionName, $value)
+    public function setOption($optionName, $value): void
     {
         if ($optionName === CURLOPT_HTTPHEADER) {
             throw new InvalidArgumentException("Setting CURL headers is only possible via the request object and not by using the setOption method.", 1633334307);
@@ -95,6 +95,9 @@ public function sendRequest(RequestInterface $request): ResponseInterface
                 curl_setopt($curlHandle, CURLOPT_PUT, true);
                 if ($content !== '') {
                     $inFileHandler = fopen('php://temp', 'r+');
+                    if ($inFileHandler === false) {
+                        throw new \RuntimeException('Failed to open php://temp', 1744451653);
+                    }
                     fwrite($inFileHandler, $content);
                     rewind($inFileHandler);
                     curl_setopt_array($curlHandle, [
@@ -111,7 +114,8 @@ public function sendRequest(RequestInterface $request): ResponseInterface
             default:
                 $body = $content !== '' ? $content : $request->getUri()->getQuery();
                 curl_setopt($curlHandle, CURLOPT_POSTFIELDS, $body);
-                curl_setopt($curlHandle, CURLOPT_CUSTOMREQUEST, $request->getMethod());
+                $method = $request->getMethod();
+                curl_setopt($curlHandle, CURLOPT_CUSTOMREQUEST, $method === '' ? null : $method);
         }
 
         $preparedHeaders = [];
@@ -134,7 +138,7 @@ public function sendRequest(RequestInterface $request): ResponseInterface
         }
 
         $curlResult = curl_exec($curlHandle);
-        if ($curlResult === false) {
+        if (!is_string($curlResult)) {
             throw new CurlEngineException(sprintf('cURL reported error code %s with message "%s". Last requested URL was "%s" (%s).', curl_errno($curlHandle), curl_error($curlHandle), curl_getinfo($curlHandle, CURLINFO_EFFECTIVE_URL), $request->getMethod()), 1338906040);
         }
 
diff --git a/Neos.Flow/Classes/Http/Client/InternalRequestEngine.php b/Neos.Flow/Classes/Http/Client/InternalRequestEngine.php
index efe9b87913..65e5260214 100644
--- a/Neos.Flow/Classes/Http/Client/InternalRequestEngine.php
+++ b/Neos.Flow/Classes/Http/Client/InternalRequestEngine.php
@@ -174,7 +174,7 @@ public function getRouter(): RouterInterface
     /**
      * Prepare a response in case an error occurred.
      *
-     * @param object $exception \Exception or \Throwable
+     * @param \Throwable $exception
      * @param ResponseInterface $response
      * @return ResponseInterface
      */
@@ -197,7 +197,7 @@ protected function prepareErrorResponse($exception, ResponseInterface $response)
         return $response
             ->withStatus($statusCode)
             ->withBody($this->contentFactory->createStream($content))
-            ->withHeader('X-Flow-ExceptionCode', $exception->getCode())
+            ->withHeader('X-Flow-ExceptionCode', (string)$exception->getCode())
             ->withHeader('X-Flow-ExceptionMessage', base64_encode($exception->getMessage()));
     }
 }
diff --git a/Neos.Flow/Classes/Http/ContentStream.php b/Neos.Flow/Classes/Http/ContentStream.php
index b502c8da61..3e6d229e76 100644
--- a/Neos.Flow/Classes/Http/ContentStream.php
+++ b/Neos.Flow/Classes/Http/ContentStream.php
@@ -59,6 +59,9 @@ public function __construct($stream, $mode = 'r')
     public static function fromContents(string $contents): self
     {
         $handle = fopen('php://memory', 'r+');
+        if ($handle === false) {
+            throw new \RuntimeException('Failed to open php://memory', 1744451485);
+        }
         fwrite($handle, $contents);
         rewind($handle);
         return new static($handle);
@@ -71,12 +74,14 @@ public static function fromContents(string $contents): self
      */
     public function close()
     {
-        if (!$this->resource) {
+        if ($this->resource === null) {
             return;
         }
 
         $resource = $this->detach();
-        fclose($resource);
+        if ($resource !== null) {
+            fclose($resource);
+        }
     }
 
     /**
@@ -100,10 +105,10 @@ public function detach()
      * @param string|resource $stream
      * @param string $mode
      */
-    public function replace($stream, $mode = 'r')
+    public function replace(mixed $stream, $mode = 'r'): void
     {
         $this->close();
-        if (!is_resource($stream)) {
+        if (is_string($stream)) {
             $stream = @fopen($stream, $mode);
         }
 
@@ -127,6 +132,7 @@ public function getSize()
 
         $stats = fstat($this->resource);
 
+        /** @phpstan-ignore offsetAccess.nonOffsetAccessible (size is available in fstat) */
         return $stats['size'];
     }
 
@@ -218,7 +224,7 @@ public function seek($offset, $whence = SEEK_SET)
      * @link http://www.php.net/manual/en/function.fseek.php
      * @throws \RuntimeException on failure.
      */
-    public function rewind()
+    public function rewind(): bool
     {
         return $this->seek(0);
     }
@@ -227,6 +233,7 @@ public function rewind()
      * Returns whether or not the stream is writable.
      *
      * @return bool
+     * @phpstan-assert-if-true resource $this->resource
      */
     public function isWritable()
     {
@@ -272,6 +279,7 @@ public function write($string)
      * Returns whether or not the stream is readable.
      *
      * @return bool
+     * @phpstan-assert-if-true resource $this->resource
      */
     public function isReadable()
     {
@@ -288,14 +296,14 @@ public function isReadable()
     /**
      * Read data from the stream.
      *
-     * @param int $length Read up to $length bytes from the object and return
+     * @param int<1, max> $length Read up to $length bytes from the object and return
      *     them. Fewer than $length bytes may be returned if underlying stream
      *     call returns fewer bytes.
      * @return string Returns the data read from the stream, or an empty string
      *     if no bytes are available.
      * @throws \RuntimeException if an error occurs.
      */
-    public function read($length)
+    public function read(int $length)
     {
         $this->ensureResourceReadable();
 
@@ -341,6 +349,9 @@ public function getContents()
      */
     public function getMetadata($key = null)
     {
+        if (!$this->resource) {
+            return null;
+        }
         if ($key === null) {
             return stream_get_meta_data($this->resource);
         }
@@ -355,8 +366,9 @@ public function getMetadata($key = null)
 
     /**
      * Throw an exception if the current resource is not readable.
+     * @phpstan-assert resource $this->resource
      */
-    protected function ensureResourceReadable()
+    protected function ensureResourceReadable(): void
     {
         if ($this->isReadable() === false) {
             throw new \RuntimeException('Stream is not readable.', 1453892039);
@@ -365,8 +377,9 @@ protected function ensureResourceReadable()
 
     /**
      * Throw an exception if the current resource is not valid.
+     * @phpstan-assert resource $this->resource
      */
-    protected function ensureResourceOpen()
+    protected function ensureResourceOpen(): void
     {
         if (!$this->isValidResource($this->resource)) {
             throw new \RuntimeException('No resource available to apply operation', 1453891806);
@@ -374,7 +387,9 @@ protected function ensureResourceOpen()
     }
 
     /**
+     * @param mixed $resource
      * @return boolean
+     * @phpstan-assert-if-true resource $resource
      */
     protected function isValidResource($resource)
     {
@@ -406,9 +421,7 @@ public function __toString()
 
             return $this->getContents();
         } catch (\Exception $e) {
-            if ($this->logger instanceof LoggerInterface) {
-                $this->logger->error(sprintf('Tried to convert a http content stream to a string but an exception occured: [%s] - %s', $e->getCode(), $e->getMessage()), ['exception' => $e] + LogEnvironment::fromMethodName(__METHOD__));
-            }
+            $this->logger->error(sprintf('Tried to convert a http content stream to a string but an exception occured: [%s] - %s', $e->getCode(), $e->getMessage()), ['exception' => $e] + LogEnvironment::fromMethodName(__METHOD__));
             return '';
         }
     }
diff --git a/Neos.Flow/Classes/Http/Cookie.php b/Neos.Flow/Classes/Http/Cookie.php
index d1a06e59f0..8bd3882779 100644
--- a/Neos.Flow/Classes/Http/Cookie.php
+++ b/Neos.Flow/Classes/Http/Cookie.php
@@ -54,7 +54,7 @@ class Cookie
     protected $name;
 
     /**
-     * @var string
+     * @var mixed
      */
     protected $value;
 
@@ -66,18 +66,18 @@ class Cookie
 
     /**
      * Number of seconds until the cookie expires (RFC 6265, 4.1.2.2)
-     * @var integer
+     * @var ?integer
      */
     protected $maximumAge;
 
     /**
      * Hosts to which this cookie will be sent (RFC 6265, 4.1.2.3)
-     * @var string
+     * @var ?string
      */
     protected $domain;
 
     /**
-     * @var string
+     * @var ?string
      */
     protected $path;
 
@@ -113,30 +113,24 @@ class Cookie
      *
      * @param string $name The cookie name as a valid token (RFC 2616)
      * @param mixed $value The value to store in the cookie. Must be possible to cast into a string.
-     * @param integer|\DateTime $expires Date and time after which this cookie expires.
-     * @param integer $maximumAge Number of seconds until the cookie expires.
-     * @param string $domain The host to which the user agent will send this cookie
-     * @param string $path The path describing the scope of this cookie
+     * @param integer|\DateTimeInterface $expires Date and time after which this cookie expires.
+     * @param ?integer $maximumAge Number of seconds until the cookie expires.
+     * @param ?string $domain The host to which the user agent will send this cookie
+     * @param ?string $path The path describing the scope of this cookie
      * @param boolean $secure If this cookie should only be sent through a "secure" channel by the user agent
      * @param boolean $httpOnly If this cookie should only be used through the HTTP protocol
      * @param string $sameSite If this cookie should restricted to a first-party or top-level navigation or third-party context
      * @api
      * @throws \InvalidArgumentException
      */
-    public function __construct($name, $value = null, $expires = 0, $maximumAge = null, $domain = null, $path = '/', $secure = false, $httpOnly = true, $sameSite = null)
+    public function __construct($name, $value = null, int|\DateTimeInterface $expires = 0, ?int $maximumAge = null, $domain = null, ?string $path = '/', $secure = false, $httpOnly = true, $sameSite = null)
     {
         if (preg_match(self::PATTERN_TOKEN, $name) !== 1) {
             throw new \InvalidArgumentException('The parameter "name" passed to the Cookie constructor must be a valid token as per RFC 2616, Section 2.2.', 1345101977);
         }
-        if ($expires instanceof \Datetime) {
+        if ($expires instanceof \DateTimeInterface) {
             $expires = $expires->getTimestamp();
         }
-        if (!is_int($expires)) {
-            throw new \InvalidArgumentException('The parameter "expires" passed to the Cookie constructor must be a unix timestamp or a DateTime object.', 1345108785);
-        }
-        if ($maximumAge !== null && !is_int($maximumAge)) {
-            throw new \InvalidArgumentException('The parameter "maximumAge" passed to the Cookie constructor must be an integer value.', 1345108786);
-        }
         if ($domain !== null && preg_match(self::PATTERN_DOMAIN, $domain) !== 1) {
             throw new \InvalidArgumentException('The parameter "domain" passed to the Cookie constructor must be a valid domain as per RFC 6265, Section 4.1.2.3.', 1345116246);
         }
@@ -329,7 +323,7 @@ public function getMaximumAge()
     /**
      * Returns the domain this cookie is valid for.
      *
-     * @return string The domain name
+     * @return ?string The domain name
      * @api
      */
     public function getDomain()
@@ -340,7 +334,7 @@ public function getDomain()
     /**
      * Returns the path this cookie is valid for.
      *
-     * @return string The path
+     * @return ?string The path
      * @api
      */
     public function getPath()
diff --git a/Neos.Flow/Classes/Http/Headers.php b/Neos.Flow/Classes/Http/Headers.php
index 6f12190574..661cce0c41 100644
--- a/Neos.Flow/Classes/Http/Headers.php
+++ b/Neos.Flow/Classes/Http/Headers.php
@@ -18,17 +18,18 @@
  *
  * @deprecated Headers will be only accessed via request in the future, if this class stays, then as internal implementation detail.
  * @Flow\Proxy(false)
+ * @implements \Iterator<string,mixed>
  * TODO: case-insensitive header name matching
  */
 class Headers implements \Iterator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected array $fields = ['Cache-Control' => []];
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected array $cookies = [];
 
@@ -40,7 +41,7 @@ class Headers implements \Iterator
     /**
      * Constructs a new Headers object.
      *
-     * @param array $fields Field names and their values (either as single value or array of values)
+     * @param array<string, mixed> $fields Field names and their values (either as single value or array of values)
      */
     public function __construct(array $fields = [])
     {
@@ -53,7 +54,7 @@ public function __construct(array $fields = [])
     /**
      * Creates a new Headers instance from the given $_SERVER-superglobal-like array.
      *
-     * @param array $server An array similar or equal to $_SERVER, containing headers in the form of "HTTP_FOO_BAR"
+     * @param array<string,mixed> $server An array similar or equal to $_SERVER, containing headers in the form of "HTTP_FOO_BAR"
      * @return Headers
      */
     public static function createFromServer(array $server)
@@ -88,7 +89,7 @@ public static function createFromServer(array $server)
      * GMT previously. GMT is used synonymously with UTC as per RFC 2616 3.3.1.
      *
      * @param string $name Name of the header, for example "Location", "Content-Description" etc.
-     * @param array|string|\DateTime $values An array of values or a single value for the specified header field
+     * @param array<mixed>|string|\DateTime|\DateTimeImmutable $values An array of values or a single value for the specified header field
      * @param boolean $replaceExistingHeader If a header with the same name should be replaced. Default is true.
      * @return void
      * @throws \InvalidArgumentException
@@ -96,10 +97,13 @@ public static function createFromServer(array $server)
      */
     public function set($name, $values, $replaceExistingHeader = true)
     {
-        if ($values instanceof \DateTimeInterface) {
+        if ($values instanceof \DateTime) {
             $date = clone $values;
             $date->setTimezone(new \DateTimeZone('GMT'));
             $values = [$date->format('D, d M Y H:i:s') . ' GMT'];
+        } elseif ($values instanceof \DateTimeImmutable) {
+            $date = $values->setTimezone(new \DateTimeZone('GMT'));
+            $values = [$date->format('D, d M Y H:i:s') . ' GMT'];
         } else {
             $values = (array) $values;
         }
@@ -161,7 +165,7 @@ public function getRaw(string $name): array
      * Dates are returned as DateTime objects with the timezone set to GMT.
      *
      * @param string $name Name of the header, for example "Location", "Content-Description" etc.
-     * @return array|string|null An array of field values if multiple headers of that name exist, a string value if only one value exists and NULL if there is no such header.
+     * @return array<mixed>|string|null An array of field values if multiple headers of that name exist, a string value if only one value exists and NULL if there is no such header.
      * @api
      */
     public function get($name)
@@ -200,7 +204,7 @@ public function get($name)
      * Note that even for those header fields which exist only one time, the value is
      * returned as an array (with a single item).
      *
-     * @return array
+     * @return array<string,mixed>
      * @api
      */
     public function getAll()
@@ -384,7 +388,7 @@ protected function setCookiesFromRawHeader($rawFieldValue)
     /**
      * Get all header lines prepared as "name: value" strings.
      *
-     * @return array
+     * @return array<mixed>
      */
     public function getPreparedValues()
     {
@@ -398,8 +402,8 @@ public function getPreparedValues()
 
     /**
      * @param string $headerName
-     * @param array $values
-     * @return array
+     * @param array<mixed> $values
+     * @return array<mixed>
      */
     private function prepareValues($headerName, array $values)
     {
@@ -413,7 +417,7 @@ private function prepareValues($headerName, array $values)
 
     /**
      * @param string $headerName
-     * @param array $values
+     * @param array<mixed> $values
      * @return string
      */
     private function renderValuesFor($headerName, array $values)
diff --git a/Neos.Flow/Classes/Http/Helper/ArgumentsHelper.php b/Neos.Flow/Classes/Http/Helper/ArgumentsHelper.php
index 331c146c24..01df53c157 100644
--- a/Neos.Flow/Classes/Http/Helper/ArgumentsHelper.php
+++ b/Neos.Flow/Classes/Http/Helper/ArgumentsHelper.php
@@ -25,10 +25,10 @@ abstract class ArgumentsHelper
      *
      * The order of merging is GET, POST, FILES, with later items overriding earlier ones.
      *
-     * @param array $getArguments Arguments as found in $_GET
-     * @param array $postArguments Arguments as found in $_POST
-     * @param array $untangledFiles Untangled $_FILES as provided by \Neos\Flow\Http\Helper\UploadedFilesHelper::untangleFilesArray
-     * @return array the unified arguments
+     * @param array<mixed> $getArguments Arguments as found in $_GET
+     * @param array<mixed> $postArguments Arguments as found in $_POST
+     * @param array<mixed> $untangledFiles Untangled $_FILES as provided by \Neos\Flow\Http\Helper\UploadedFilesHelper::untangleFilesArray
+     * @return array<mixed> the unified arguments
      * @see \Neos\Flow\Http\Helper\UploadedFilesHelper::untangleFilesArray
      */
     public static function buildUnifiedArguments(array $getArguments, array $postArguments, array $untangledFiles): array
@@ -40,8 +40,9 @@ public static function buildUnifiedArguments(array $getArguments, array $postArg
     }
 
     /**
-     * @param array ...$argumentArrays
-     * @return array
+     * @param array<mixed> $arguments
+     * @param array<mixed> ...$argumentArrays
+     * @return array<mixed>
      */
     public static function mergeArgumentArrays(array $arguments, array ...$argumentArrays): array
     {
diff --git a/Neos.Flow/Classes/Http/Helper/MediaTypeHelper.php b/Neos.Flow/Classes/Http/Helper/MediaTypeHelper.php
index 67cbf296e8..9eb5b5d50d 100644
--- a/Neos.Flow/Classes/Http/Helper/MediaTypeHelper.php
+++ b/Neos.Flow/Classes/Http/Helper/MediaTypeHelper.php
@@ -24,12 +24,12 @@ abstract class MediaTypeHelper
      * If no "Accept" header was found all media types are acceptable.
      *
      * @param RequestInterface $request
-     * @return array
+     * @return array<mixed>
      */
     public static function determineAcceptedMediaTypes(RequestInterface $request): array
     {
         $rawValues = $request->getHeaderLine('Accept');
-        if (empty($rawValues) || !is_string($rawValues)) {
+        if (empty($rawValues)) {
             return ['*/*'];
         }
         $acceptedMediaTypes = self::parseContentNegotiationQualityValues($rawValues);
@@ -41,8 +41,8 @@ public static function determineAcceptedMediaTypes(RequestInterface $request): a
      * Returns the best fitting IANA media type after applying the content negotiation
      * rules on the accepted media types.
      *
-     * @param array $acceptedMediaTypes A list of accepted media types according to a request.
-     * @param array $supportedMediaTypes A list of media types which are supported by the application / controller
+     * @param array<string> $acceptedMediaTypes A list of accepted media types according to a request.
+     * @param array<string> $supportedMediaTypes A list of media types which are supported by the application / controller
      * @param bool $trim If TRUE, only the type/subtype of the media type is returned. If FALSE, the full original media type string is returned.
      * @return string The media type and sub type which matched, NULL if none matched
      */
@@ -66,17 +66,20 @@ public static function negotiateMediaType(array $acceptedMediaTypes, array $supp
      * Values and splitting the options into an array list, ordered by user preference.
      *
      * @param string $rawValues The raw Accept* Header field value
-     * @return array The parsed list of field values, ordered by user preference
+     * @return array<mixed> The parsed list of field values, ordered by user preference
      */
     public static function parseContentNegotiationQualityValues(string $rawValues): array
     {
         $acceptedTypes = array_map(
             function ($acceptType) {
                 $typeAndQuality = preg_split('/;\s*q=/', $acceptType);
+                if ($typeAndQuality === false) {
+                    throw new \InvalidArgumentException('Invalid accept type ' . $acceptType, 1744449962);
+                }
 
                 return [$typeAndQuality[0], (isset($typeAndQuality[1]) ? (float)$typeAndQuality[1] : '')];
             },
-            preg_split('/,\s*/', $rawValues)
+            preg_split('/,\s*/', $rawValues) ?: []
         );
 
         $flattenedAcceptedTypes = [];
diff --git a/Neos.Flow/Classes/Http/Helper/RequestInformationHelper.php b/Neos.Flow/Classes/Http/Helper/RequestInformationHelper.php
index db7733b833..59f13bd083 100644
--- a/Neos.Flow/Classes/Http/Helper/RequestInformationHelper.php
+++ b/Neos.Flow/Classes/Http/Helper/RequestInformationHelper.php
@@ -159,8 +159,8 @@ public static function getContentCharset(RequestInterface $request): string
     /**
      * Extract header key/value pairs from a $_SERVER array.
      *
-     * @param array $server
-     * @return array
+     * @param array<string,mixed> $server
+     * @return array<string,mixed>
      */
     public static function extractHeadersFromServerVariables(array $server): array
     {
diff --git a/Neos.Flow/Classes/Http/Helper/ResponseInformationHelper.php b/Neos.Flow/Classes/Http/Helper/ResponseInformationHelper.php
index f120eba029..3b89f09a56 100644
--- a/Neos.Flow/Classes/Http/Helper/ResponseInformationHelper.php
+++ b/Neos.Flow/Classes/Http/Helper/ResponseInformationHelper.php
@@ -141,7 +141,7 @@ public static function generateStatusLine(ResponseInterface $response): string
      * Prepare array of header lines for this response
      *
      * @param ResponseInterface $response
-     * @return array
+     * @return array<int,string>
      */
     public static function prepareHeaders(ResponseInterface $response): array
     {
@@ -230,7 +230,7 @@ public static function makeStandardsCompliant(ResponseInterface $response, Reque
         }
 
         if (!$response->hasHeader('Content-Length') && $response->getBody()->getSize() !== null) {
-            $response = $response->withHeader('Content-Length', $response->getBody()->getSize());
+            $response = $response->withHeader('Content-Length', (string)$response->getBody()->getSize());
         }
 
         if ($request->getMethod() === 'HEAD') {
diff --git a/Neos.Flow/Classes/Http/Helper/UploadedFilesHelper.php b/Neos.Flow/Classes/Http/Helper/UploadedFilesHelper.php
index 7473fbe76b..f1693789eb 100644
--- a/Neos.Flow/Classes/Http/Helper/UploadedFilesHelper.php
+++ b/Neos.Flow/Classes/Http/Helper/UploadedFilesHelper.php
@@ -24,9 +24,9 @@ abstract class UploadedFilesHelper
 {
     /**
      * @param UploadedFileInterface[]|mixed[][] $uploadedFiles A (deep) array of UploadedFile or an untangled $_FILES array
-     * @param array $arguments
-     * @param array $currentPath internal argument for recursion
-     * @return array The nested array of paths and uploaded files
+     * @param array<mixed> $arguments
+     * @param array<mixed> $currentPath internal argument for recursion
+     * @return array<mixed> The nested array of paths and uploaded files
      */
     public static function upcastUploadedFiles(array $uploadedFiles, array $arguments, array $currentPath = []): array
     {
@@ -64,7 +64,7 @@ public static function upcastUploadedFiles(array $uploadedFiles, array $argument
 
     /**
      * @param UploadedFileInterface $uploadedFile
-     * @param string|array $originallySubmittedResource
+     * @param string|array{__identity: string} $originallySubmittedResource
      * @param string $collectionName
      * @return FlowUploadedFile
      */
@@ -87,8 +87,8 @@ protected static function upcastUploadedFile(UploadedFileInterface $uploadedFile
     /**
      * Transforms the convoluted _FILES superglobal into a manageable form.
      *
-     * @param array $convolutedFiles The _FILES superglobal or something with the same structure
-     * @return array Untangled files
+     * @param array<mixed> $convolutedFiles The _FILES superglobal or something with the same structure
+     * @return array<mixed> Untangled files
      */
     public static function untangleFilesArray(array $convolutedFiles): array
     {
@@ -124,9 +124,9 @@ public static function untangleFilesArray(array $convolutedFiles): array
     /**
      * Returns an array of all possible "field paths" for the given array.
      *
-     * @param array $structure The array to walk through
+     * @param array<mixed> $structure The array to walk through
      * @param string $firstLevelFieldName
-     * @return array An array of paths (as arrays) in the format ["key1", "key2", "key3"] ...
+     * @return array<mixed> An array of paths (as arrays) in the format ["key1", "key2", "key3"] ...
      */
     protected static function calculateFieldPathsAsArray(array $structure, ?string $firstLevelFieldName = null): array
     {
diff --git a/Neos.Flow/Classes/Http/Middleware/MethodOverrideMiddleware.php b/Neos.Flow/Classes/Http/Middleware/MethodOverrideMiddleware.php
index 2aa13861b8..27cb74444a 100644
--- a/Neos.Flow/Classes/Http/Middleware/MethodOverrideMiddleware.php
+++ b/Neos.Flow/Classes/Http/Middleware/MethodOverrideMiddleware.php
@@ -25,7 +25,7 @@ public function process(ServerRequestInterface $request, RequestHandlerInterface
     {
         if ($request->getMethod() === 'POST') {
             $parsedBody = $request->getParsedBody();
-            if (isset($parsedBody['__method'])) {
+            if (is_array($parsedBody) && isset($parsedBody['__method'])) {
                 $request = $request->withMethod($parsedBody['__method']);
             } elseif ($request->hasHeader('X-Http-Method-Override')) {
                 $request = $request->withMethod($request->getHeaderLine('X-Http-Method-Override'));
diff --git a/Neos.Flow/Classes/Http/Middleware/MiddlewaresChain.php b/Neos.Flow/Classes/Http/Middleware/MiddlewaresChain.php
index 97cc908f09..cf7e7dbdc4 100644
--- a/Neos.Flow/Classes/Http/Middleware/MiddlewaresChain.php
+++ b/Neos.Flow/Classes/Http/Middleware/MiddlewaresChain.php
@@ -31,13 +31,8 @@ final class MiddlewaresChain implements RequestHandlerInterface
      */
     private $stepCallbacks = [];
 
-    public function __construct(array $middlewaresChain)
+    public function __construct(MiddlewareInterface ...$middlewaresChain)
     {
-        array_walk($middlewaresChain, static function ($middleware) {
-            if (!$middleware instanceof MiddlewareInterface) {
-                throw new Exception(sprintf('Invalid element "%s" in middleware chain. Must implement %s.', is_object($middleware) ? get_class($middleware) : gettype($middleware), MiddlewareInterface::class));
-            }
-        });
         $this->chain = $middlewaresChain;
     }
 
diff --git a/Neos.Flow/Classes/Http/Middleware/MiddlewaresChainFactory.php b/Neos.Flow/Classes/Http/Middleware/MiddlewaresChainFactory.php
index b85e51de3a..37a387fe59 100644
--- a/Neos.Flow/Classes/Http/Middleware/MiddlewaresChainFactory.php
+++ b/Neos.Flow/Classes/Http/Middleware/MiddlewaresChainFactory.php
@@ -32,7 +32,7 @@ class MiddlewaresChainFactory
     protected $objectManager;
 
     /**
-     * @param array $chainConfiguration
+     * @param array<mixed> $chainConfiguration
      * @return MiddlewaresChain
      * @throws Exception
      */
@@ -53,6 +53,6 @@ public function create(array $chainConfiguration): MiddlewaresChain
             $middlewaresChain[] = $middleware;
         }
 
-        return new MiddlewaresChain($middlewaresChain);
+        return new MiddlewaresChain(...$middlewaresChain);
     }
 }
diff --git a/Neos.Flow/Classes/Http/Middleware/RequestBodyParsingMiddleware.php b/Neos.Flow/Classes/Http/Middleware/RequestBodyParsingMiddleware.php
index 748372fdc2..86e3c28f6b 100644
--- a/Neos.Flow/Classes/Http/Middleware/RequestBodyParsingMiddleware.php
+++ b/Neos.Flow/Classes/Http/Middleware/RequestBodyParsingMiddleware.php
@@ -33,26 +33,26 @@ class RequestBodyParsingMiddleware implements MiddlewareInterface
     /**
      * @inheritDoc
      */
-    public function process(ServerRequestInterface $request, RequestHandlerInterface $next): ResponseInterface
+    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
     {
         if (!empty($request->getParsedBody())) {
-            return $next->handle($request);
+            return $handler->handle($request);
         }
         $parsedBody = $this->parseRequestBody($request);
-        return $next->handle($request->withParsedBody($parsedBody));
+        return $handler->handle($request->withParsedBody($parsedBody));
     }
 
     /**
      * Parses the request body according to the media type.
      *
      * @param ServerRequestInterface $httpRequest
-     * @return null|array|string|integer
+     * @return null|array<mixed>
      */
     protected function parseRequestBody(ServerRequestInterface $httpRequest)
     {
         $requestBody = $httpRequest->getBody()->getContents();
-        if ($requestBody === null || $requestBody === '') {
-            return $requestBody;
+        if ($requestBody === '') {
+            return null;
         }
 
         /** @var MediaTypeConverterInterface $mediaTypeConverter */
@@ -62,6 +62,9 @@ protected function parseRequestBody(ServerRequestInterface $httpRequest)
         $requestedContentType = $httpRequest->getHeaderLine('Content-Type');
         $propertyMappingConfiguration->setTypeConverterOption(MediaTypeConverterInterface::class, MediaTypeConverterInterface::CONFIGURATION_MEDIA_TYPE, $requestedContentType);
         // FIXME: The MediaTypeConverter returns an empty array for "error cases", which might be unintended
-        return $this->propertyMapper->convert($requestBody, 'array', $propertyMappingConfiguration);
+        /** @var array<mixed> $array */
+        $array = $this->propertyMapper->convert($requestBody, 'array', $propertyMappingConfiguration);
+
+        return $array;
     }
 }
diff --git a/Neos.Flow/Classes/Http/Middleware/SecurityEntryPointMiddleware.php b/Neos.Flow/Classes/Http/Middleware/SecurityEntryPointMiddleware.php
index 0f82567b99..8bfcb76bd5 100644
--- a/Neos.Flow/Classes/Http/Middleware/SecurityEntryPointMiddleware.php
+++ b/Neos.Flow/Classes/Http/Middleware/SecurityEntryPointMiddleware.php
@@ -8,6 +8,7 @@
 use Neos\Flow\Http\ServerRequestAttributes;
 use Neos\Flow\Log\Utility\LogEnvironment;
 use Neos\Flow\Mvc\ActionRequestFactory;
+use Neos\Flow\Security\Authentication\EntryPointInterface;
 use Neos\Flow\Security\Authentication\Token\SessionlessTokenInterface;
 use Neos\Flow\Security\Authentication\TokenInterface;
 use Neos\Flow\Security\Context;
@@ -55,7 +56,6 @@ public function process(ServerRequestInterface $request, RequestHandlerInterface
         try {
             return $next->handle($request->withAttribute(ServerRequestAttributes::ACTION_REQUEST, $actionRequest));
         } catch (AuthenticationRequiredException $authenticationException) {
-            /** @var TokenInterface[] $tokensWithEntryPoint */
             $tokensWithEntryPoint = array_filter($this->securityContext->getAuthenticationTokens(), static function (TokenInterface $token) {
                 return $token->getAuthenticationEntryPoint() !== null;
             });
@@ -72,6 +72,7 @@ public function process(ServerRequestInterface $request, RequestHandlerInterface
                 }
 
                 $entryPoint = $token->getAuthenticationEntryPoint();
+                assert($entryPoint instanceof EntryPointInterface);
                 $this->securityLogger->debug(sprintf('Starting authentication with entry point of type "%s"', \get_class($entryPoint)), LogEnvironment::fromMethodName(__METHOD__));
 
                 // Only store the intercepted request if it is a GET request (otherwise it can't be resumed properly)
diff --git a/Neos.Flow/Classes/Http/Middleware/SessionMiddleware.php b/Neos.Flow/Classes/Http/Middleware/SessionMiddleware.php
index d143b52c08..824188e29b 100644
--- a/Neos.Flow/Classes/Http/Middleware/SessionMiddleware.php
+++ b/Neos.Flow/Classes/Http/Middleware/SessionMiddleware.php
@@ -31,7 +31,8 @@ class SessionMiddleware implements MiddlewareInterface
 {
     /**
      * @Flow\InjectConfiguration(package="Neos.Flow", path="session")
-     * @var array
+     * @todo enforce with extractor
+     * @var array{name: string, cookie: array{lifetime: int, domain: string, path: string, secure: bool, httponly: true, samesite: string}}
      */
     protected $sessionSettings;
 
@@ -41,20 +42,19 @@ class SessionMiddleware implements MiddlewareInterface
      */
     protected $sessionManager;
 
-    public function process(ServerRequestInterface $request, RequestHandlerInterface $next): ResponseInterface
+    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
     {
         if (!$this->sessionManager instanceof SessionManager) {
-            return $next->handle($request);
+            return $handler->handle($request);
         }
 
         $sessionCookieName = $this->sessionSettings['name'];
-        /** @var ServerRequestInterface $request */
         $cookies = $request->getCookieParams();
 
         if (!isset($cookies[$sessionCookieName])) {
             $sessionCookie = $this->prepareCookie($sessionCookieName, Algorithms::generateRandomString(32));
             $this->sessionManager->createCurrentSessionFromCookie($sessionCookie);
-            return $this->handleSetCookie($next->handle($request));
+            return $this->handleSetCookie($handler->handle($request));
         }
 
         $sessionIdentifier = $cookies[$sessionCookieName];
@@ -62,7 +62,7 @@ public function process(ServerRequestInterface $request, RequestHandlerInterface
         $this->sessionManager->initializeCurrentSessionFromCookie($sessionCookie);
         $this->sessionManager->getCurrentSession()->resume();
 
-        return $this->handleSetCookie($next->handle($request));
+        return $this->handleSetCookie($handler->handle($request));
     }
 
     /**
diff --git a/Neos.Flow/Classes/Http/Middleware/StandardsComplianceMiddleware.php b/Neos.Flow/Classes/Http/Middleware/StandardsComplianceMiddleware.php
index 75e445663e..f0199ec064 100644
--- a/Neos.Flow/Classes/Http/Middleware/StandardsComplianceMiddleware.php
+++ b/Neos.Flow/Classes/Http/Middleware/StandardsComplianceMiddleware.php
@@ -26,12 +26,12 @@
 class StandardsComplianceMiddleware implements MiddlewareInterface
 {
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $options;
 
     /**
-     * @param array $options
+     * @param array<mixed> $options
      */
     public function __construct(array $options = [])
     {
diff --git a/Neos.Flow/Classes/Http/Middleware/TrustedProxiesMiddleware.php b/Neos.Flow/Classes/Http/Middleware/TrustedProxiesMiddleware.php
index b70ab143a1..7a8f26603e 100644
--- a/Neos.Flow/Classes/Http/Middleware/TrustedProxiesMiddleware.php
+++ b/Neos.Flow/Classes/Http/Middleware/TrustedProxiesMiddleware.php
@@ -38,14 +38,15 @@ class TrustedProxiesMiddleware implements MiddlewareInterface
     const HOST_PATTERN = '(?:host=(?<host>"[^"]+"|[0-9a-z_\.:\-]+))';
 
     /**
-     * @var array
+     * @var array{proxies: "*"|array<string>, headers?: string|array<string,string>}
      */
     protected $settings;
 
     /**
      * Injects the configuration settings
      *
-     * @param array $settings
+     * @todo enforce with extractor
+     * @param array<mixed> $settings
      * @return void
      * @throws InvalidConfigurationException
      */
@@ -113,8 +114,8 @@ public function process(ServerRequestInterface $request, RequestHandlerInterface
     }
 
     /**
-     * @param array $array
-     * @return array
+     * @param array<string> $array
+     * @return array<int,string>
      */
     protected function unquoteArray($array): array
     {
@@ -125,8 +126,8 @@ protected function unquoteArray($array): array
 
     /**
      * @param string $type The header value type to retrieve from the Forwarded header value. One of the HEADER_* constants.
-     * @param array $headerValues The Forwarded header value, e.g. "for=192.168.178.5; host=www.acme.org:8080"
-     * @return array|null The array of values for the header type or null if the header
+     * @param array<string> $headerValues The Forwarded header value, e.g. "for=192.168.178.5; host=www.acme.org:8080"
+     * @return array<mixed>|null The array of values for the header type or null if the header
      */
     protected function getForwardedHeader($type, array $headerValues)
     {
@@ -139,6 +140,9 @@ protected function getForwardedHeader($type, array $headerValues)
             return null;
         }
         $headerValue = reset($headerValues);
+        if (!$headerValue) {
+            return null;
+        }
         preg_match_all('/' . $patterns[$type] . '/i', $headerValue, $matches);
         $matchedHeader = $this->unquoteArray($matches[1]);
         if ($matchedHeader === []) {
@@ -152,7 +156,7 @@ protected function getForwardedHeader($type, array $headerValues)
      *
      * @param string $type One of the HEADER_* constants
      * @param ServerRequestInterface $request The request to get the trusted proxy header from
-     * @return \Generator<array|null> Yields the array of the values for this header type or yields NULL if this header type should not be trusted
+     * @return \Generator<array<mixed>|null> Yields the array of the values for this header type or yields NULL if this header type should not be trusted
      */
     protected function getTrustedProxyHeaderValues($type, ServerRequestInterface $request)
     {
diff --git a/Neos.Flow/Classes/Http/RequestHandler.php b/Neos.Flow/Classes/Http/RequestHandler.php
index 58255533ab..eb8561ad5b 100644
--- a/Neos.Flow/Classes/Http/RequestHandler.php
+++ b/Neos.Flow/Classes/Http/RequestHandler.php
@@ -36,7 +36,7 @@ class RequestHandler implements HttpRequestHandlerInterface
     protected $middlewaresChain;
 
     /**
-     * @var ServerRequestInterface
+     * @var ?ServerRequestInterface
      */
     protected $httpRequest;
 
@@ -89,6 +89,7 @@ public function getPriority()
     /**
      * Handles a HTTP request
      *
+     * @phpstan-assert ServerRequest $this->httpRequest
      * @return void
      */
     public function handleRequest()
@@ -102,6 +103,7 @@ public function handleRequest()
         $this->middlewaresChain->onStep(function (ServerRequestInterface $request) {
             $this->httpRequest = $request;
         });
+        assert($this->httpRequest instanceof ServerRequestInterface);
         $this->httpResponse = $this->middlewaresChain->handle($this->httpRequest);
 
         $this->sendResponse($this->httpResponse);
@@ -112,7 +114,7 @@ public function handleRequest()
     /**
      * Returns the currently handled HTTP request
      *
-     * @return ServerRequestInterface
+     * @return ?ServerRequestInterface
      * @api
      */
     public function getHttpRequest()
@@ -148,7 +150,7 @@ protected function resolveDependencies()
      * Send the HttpResponse of the component context to the browser and flush all output buffers.
      * @param ResponseInterface $response
      */
-    protected function sendResponse(ResponseInterface $response)
+    protected function sendResponse(ResponseInterface $response): void
     {
         ob_implicit_flush();
         foreach (ResponseInformationHelper::prepareHeaders($response) as $prepareHeader) {
diff --git a/Neos.Flow/Classes/Http/UploadedFile.php b/Neos.Flow/Classes/Http/UploadedFile.php
index 90d9139dff..399116c800 100644
--- a/Neos.Flow/Classes/Http/UploadedFile.php
+++ b/Neos.Flow/Classes/Http/UploadedFile.php
@@ -16,12 +16,12 @@
 class UploadedFile implements UploadedFileInterface
 {
     /**
-     * @var string
+     * @var ?string
      */
     protected $clientFilename;
 
     /**
-     * @var string
+     * @var ?string
      */
     protected $clientMediaType;
 
@@ -75,7 +75,7 @@ public function __construct($streamOrFile, $size, $errorStatus, $clientFilename
      * @param string|StreamInterface|resource $streamOrFile
      * @throws InvalidArgumentException
      */
-    protected function setStreamOrFile($streamOrFile)
+    protected function setStreamOrFile($streamOrFile): void
     {
         if (is_string($streamOrFile)) {
             $this->file = $streamOrFile;
@@ -135,7 +135,14 @@ public function getStream()
             return $this->stream;
         }
 
-        return new Stream(fopen($this->file, 'rb+'));
+        if (!$this->file) {
+            throw new \RuntimeException('Missing file ' . $this->file, 1744443740);
+        }
+        $resource = fopen($this->file, 'rb+');
+        if (!$resource) {
+            throw new \RuntimeException('Failed to open file ' . $this->file, 1744442831);
+        }
+        return new Stream($resource);
     }
 
     /**
@@ -172,18 +179,20 @@ public function getStream()
      *     the second or subsequent call to the method.
      * @api PSR-7
      */
-    public function moveTo($targetPath)
+    public function moveTo(string $targetPath): void
     {
         $this->throwExceptionIfNotAccessible();
 
-        if (!is_string($targetPath) || empty($targetPath)) {
+        if (empty($targetPath)) {
             throw new InvalidArgumentException('Invalid path provided to move uploaded file to. Must be a non-empty string', 1479747624);
         }
 
+        /** @phpstan-ignore identical.alwaysTrue (FLOW_SAPITYPE can also be "Web") */
         if ($this->stream !== null || ($this->file !== null && FLOW_SAPITYPE === 'CLI')) {
             $this->moved = $this->writeFile($targetPath);
         }
 
+        /** @phpstan-ignore notIdentical.alwaysFalse, booleanAnd.alwaysFalse (FLOW_SAPITYPE can also be "Web", thus this can be true) */
         if ($this->file !== null && FLOW_SAPITYPE !== 'CLI') {
             $this->moved = move_uploaded_file($this->file, $targetPath);
         }
@@ -267,7 +276,7 @@ public function getClientMediaType()
     /**
      * @throws RuntimeException if is moved or not ok
      */
-    protected function throwExceptionIfNotAccessible()
+    protected function throwExceptionIfNotAccessible(): void
     {
         if (!$this->isOk()) {
             throw new RuntimeException('UploadedFile has the following error: ' . Files::getUploadErrorMessage($this->error), 1479743608);
diff --git a/Neos.Flow/Classes/Http/UriTemplate.php b/Neos.Flow/Classes/Http/UriTemplate.php
index 085fe134b7..1d7598518f 100644
--- a/Neos.Flow/Classes/Http/UriTemplate.php
+++ b/Neos.Flow/Classes/Http/UriTemplate.php
@@ -22,24 +22,24 @@
 class UriTemplate
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected static $variables;
 
     /**
-     * @var array
+     * @var array<string,true>
      */
     protected static $operators = [
         '+' => true, '#' => true, '.' => true, '/' => true, ';' => true, '?' => true, '&' => true
     ];
 
     /**
-     * @var array
+     * @var array<int,string>
      */
     protected static $delimiters = [':', '/', '?', '#', '[', ']', '@', '!', '$', '&', '\'', '(', ')', '*', '+', ',', ';', '='];
 
     /**
-     * @var array
+     * @var array<int,string>
      */
     protected static $encodedDelimiters = ['%3A', '%2F', '%3F', '%23', '%5B', '%5D', '%40', '%21', '%24', '%26', '%27', '%28', '%29', '%2A', '%2B', '%2C', '%3B', '%3D'];
 
@@ -47,7 +47,7 @@ class UriTemplate
      * Expand the template string using the supplied variables
      *
      * @param string $template URI template to expand
-     * @param array $variables variables to use with the expansion
+     * @param array<string,mixed> $variables variables to use with the expansion
      * @return string
      */
     public static function expand($template, array $variables)
@@ -58,13 +58,13 @@ public static function expand($template, array $variables)
 
         self::$variables = $variables;
 
-        return preg_replace_callback('/\{([^\}]+)\}/', [UriTemplate::class, 'expandMatch'], $template);
+        return preg_replace_callback('/\{([^\}]+)\}/', [UriTemplate::class, 'expandMatch'], $template) ?: '';
     }
 
     /**
      * Process an expansion
      *
-     * @param array $matches matches found in preg_replace_callback
+     * @param array{1: string} $matches matches found in preg_replace_callback
      * @return string replacement string
      */
     protected static function expandMatch(array $matches)
@@ -98,7 +98,6 @@ protected static function expandMatch(array $matches)
             if (!array_key_exists($value['value'], self::$variables) || self::$variables[$value['value']] === null) {
                 continue;
             }
-
             $variable = self::$variables[$value['value']];
             $useQueryString = $queryStringShouldBeUsed;
 
@@ -106,7 +105,7 @@ protected static function expandMatch(array $matches)
                 $expanded = self::encodeArrayVariable($variable, $value, $parsed['operator'], $separator, $useQueryString);
             } else {
                 if ($value['modifier'] === ':') {
-                    $variable = substr($variable, 0, $value['position']);
+                    $variable = substr($variable, 0, $value['position'] ?? 0);
                 }
                 $expanded = rawurlencode($variable);
                 if ($parsed['operator'] === '+' || $parsed['operator'] === '#') {
@@ -137,7 +136,7 @@ protected static function expandMatch(array $matches)
      * Parse an expression into parts
      *
      * @param string $expression Expression to parse
-     * @return array associative array of parts
+     * @return array{operator: string, values: array<int,array{value: string, modifier: string, position?: int}>} associative array of parts
      */
     protected static function parseExpression($expression)
     {
@@ -169,6 +168,7 @@ protected static function parseExpression($expression)
             $expressionPart = $configuration;
         }
 
+        /** @phpstan-ignore return.type (values resolved by reference) */
         return [
             'operator' => $operator,
             'values' => $explodedExpression
@@ -178,8 +178,8 @@ protected static function parseExpression($expression)
     /**
      * Encode arrays for use in the expanded URI string
      *
-     * @param array $variable
-     * @param array $value
+     * @param array<mixed> $variable
+     * @param array<mixed> $value
      * @param string $operator
      * @param string $separator
      * @param bool $useQueryString
@@ -247,7 +247,7 @@ protected static function encodeArrayVariable(array $variable, array $value, $op
     /**
      * Determines if an array is associative, i.e. contains at least one key that is a string.
      *
-     * @param array $array
+     * @param array<mixed> $array
      * @return boolean
      */
     protected static function isAssociative(array $array)
diff --git a/Neos.Flow/Classes/I18n/AbstractXmlParser.php b/Neos.Flow/Classes/I18n/AbstractXmlParser.php
index 597f531284..8e64778f2d 100644
--- a/Neos.Flow/Classes/I18n/AbstractXmlParser.php
+++ b/Neos.Flow/Classes/I18n/AbstractXmlParser.php
@@ -23,7 +23,7 @@ abstract class AbstractXmlParser
     /**
      * Associative array of "filename => parsed data" pairs.
      *
-     * @var array
+     * @var array<string,array<mixed>>
      */
     protected $parsedFiles;
 
@@ -33,7 +33,7 @@ abstract class AbstractXmlParser
      * Parses XML if it wasn't done before. Caches parsed data.
      *
      * @param string $sourcePath An absolute path to XML file
-     * @return array Parsed XML file
+     * @return array<mixed> Parsed XML file
      */
     public function getParsedData(string $sourcePath)
     {
@@ -56,7 +56,7 @@ protected function getRootNode(string $sourcePath): \SimpleXMLElement
         }
         libxml_use_internal_errors(true);
         // Use of simplexml_load_string/file_get_contents ia a workaround for https://bugs.php.net/bug.php?id=62577
-        $rootXmlNode = simplexml_load_string(file_get_contents($sourcePath), 'SimpleXmlElement', \LIBXML_NOWARNING);
+        $rootXmlNode = simplexml_load_string(file_get_contents($sourcePath) ?: '', 'SimpleXmlElement', \LIBXML_NOWARNING);
         if ($rootXmlNode === false) {
             $errors = [];
             foreach (libxml_get_errors() as $error) {
@@ -76,7 +76,7 @@ protected function getRootNode(string $sourcePath): \SimpleXMLElement
      * Reads and parses XML file and returns internal representation of data.
      *
      * @param string $sourcePath An absolute path to XML file
-     * @return array Parsed XML file
+     * @return array<mixed> Parsed XML file
      */
     protected function parseXmlFile(string $sourcePath)
     {
@@ -89,7 +89,7 @@ protected function parseXmlFile(string $sourcePath)
      * Returns array representation of XML data, starting from a root node.
      *
      * @param \SimpleXMLElement $root A root node
-     * @return array An array representing parsed XML file (structure depends on concrete parser)
+     * @return array<mixed> An array representing parsed XML file (structure depends on concrete parser)
      */
     abstract protected function doParsingFromRoot(\SimpleXMLElement $root);
 }
diff --git a/Neos.Flow/Classes/I18n/Cldr/CldrModel.php b/Neos.Flow/Classes/I18n/Cldr/CldrModel.php
index 5e4a6ab33b..ecd32cdc73 100644
--- a/Neos.Flow/Classes/I18n/Cldr/CldrModel.php
+++ b/Neos.Flow/Classes/I18n/Cldr/CldrModel.php
@@ -56,7 +56,7 @@ class CldrModel
     protected $sourcePaths;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $parsedData;
 
@@ -276,7 +276,7 @@ public static function getAttributeValue(string $nodeString, string $attributeNa
      * Merging is done with inheritance in mind, as defined in CLDR specification.
      *
      * @param array<string> $sourcePaths Absolute paths to CLDR files (can be one file)
-     * @return array Parsed and merged data
+     * @return array<mixed> Parsed and merged data
      */
     protected function parseFiles(array $sourcePaths): array
     {
@@ -304,7 +304,7 @@ protected function parseFiles(array $sourcePaths): array
      *
      * @param mixed $firstParsedData Part of data from first file (either array or string)
      * @param mixed $secondParsedData Part of data from second file (either array or string)
-     * @return array Data merged from two files
+     * @return array<mixed> Data merged from two files
      */
     protected function mergeTwoParsedFiles($firstParsedData, $secondParsedData)
     {
@@ -351,6 +351,9 @@ protected function resolveAliases($data, string $currentPath)
                 }
 
                 $sourcePath = self::getAttributeValue($nodeString, 'path');
+                if (!is_string($sourcePath)) {
+                    throw new \Exception('source path must be string', 1744412220);
+                }
 
                 // Change relative path to absolute one
                 $sourcePath = str_replace('../', '', $sourcePath, $countOfJumpsToParentNode);
diff --git a/Neos.Flow/Classes/I18n/Cldr/CldrParser.php b/Neos.Flow/Classes/I18n/Cldr/CldrParser.php
index 5a7ec6bb2f..bf2fe58844 100644
--- a/Neos.Flow/Classes/I18n/Cldr/CldrParser.php
+++ b/Neos.Flow/Classes/I18n/Cldr/CldrParser.php
@@ -56,7 +56,7 @@ class CldrParser extends AbstractXmlParser
      * Returns array representation of XML data, starting from a root node.
      *
      * @param \SimpleXMLElement $root A root node
-     * @return array An array representing parsed CLDR File
+     * @return array<mixed> An array representing parsed CLDR File
      * @see AbstractXmlParser::doParsingFromRoot()
      */
     protected function doParsingFromRoot(\SimpleXMLElement $root)
diff --git a/Neos.Flow/Classes/I18n/Cldr/CldrRepository.php b/Neos.Flow/Classes/I18n/Cldr/CldrRepository.php
index 54403980c0..b14dc6d8c8 100644
--- a/Neos.Flow/Classes/I18n/Cldr/CldrRepository.php
+++ b/Neos.Flow/Classes/I18n/Cldr/CldrRepository.php
@@ -51,7 +51,7 @@ class CldrRepository
      * reside and 'locale' is used to define which files are included in the
      * relation (e.g. for locale 'en_GB' files would be: root + en + en_GB).
      *
-     * @var array<CldrModel>
+     * @var array<string,CldrModel|array<string,CldrModel>>
      */
     protected $models;
 
@@ -73,13 +73,13 @@ public function injectLocalizationService(I18n\Service $localizationService)
      * file.
      *
      * @param string $filename Relative (from CLDR root) path to existing CLDR file
-     * @return CldrModel|false A CldrModel instance or false on failure
+     * @return CldrModel|false An array of CldrModel instances indexed by Locale or false on failure
      */
     public function getModel($filename)
     {
         $filename = Files::concatenatePaths([$this->cldrBasePath, $filename . '.xml']);
 
-        if (isset($this->models[$filename])) {
+        if (isset($this->models[$filename]) && $this->models[$filename] instanceof CldrModel) {
             return $this->models[$filename];
         }
 
@@ -110,7 +110,7 @@ public function getModelForLocale(I18n\Locale $locale, $directoryPath = 'main')
     {
         $directoryPath = Files::concatenatePaths([$this->cldrBasePath, $directoryPath]);
 
-        if (isset($this->models[$directoryPath][(string)$locale])) {
+        if (is_array($this->models[$directoryPath]) && isset($this->models[$directoryPath][(string)$locale])) {
             return $this->models[$directoryPath][(string)$locale];
         }
 
@@ -120,6 +120,11 @@ public function getModelForLocale(I18n\Locale $locale, $directoryPath = 'main')
 
         $filesInHierarchy = $this->findLocaleChain($locale, $directoryPath);
 
+        if (($this->models[$directoryPath] ?? null) instanceof CldrModel) {
+            throw new \Exception('Directory path ' . $directoryPath . ' is already occupied', 1744414384);
+        }
+
+        /** @phpstan-ignore offsetAccess.nonOffsetAccessible (we already checked that above. also @todo separate the arrays) */
         return $this->models[$directoryPath][(string)$locale] = new CldrModel($filesInHierarchy);
     }
 
diff --git a/Neos.Flow/Classes/I18n/Cldr/Reader/CurrencyReader.php b/Neos.Flow/Classes/I18n/Cldr/Reader/CurrencyReader.php
index 37d7351262..5f761fad05 100644
--- a/Neos.Flow/Classes/I18n/Cldr/Reader/CurrencyReader.php
+++ b/Neos.Flow/Classes/I18n/Cldr/Reader/CurrencyReader.php
@@ -37,7 +37,7 @@ class CurrencyReader
     /**
      * An array of fractions data, indexed by currency code.
      *
-     * @var array
+     * @var array<string,array{digits: int, rounding: int}>
      */
     protected $fractions;
 
@@ -81,7 +81,7 @@ public function initializeObject()
      * Returns an array with keys "digits" and "rounding", each an integer.
      *
      * @param string $currencyCode
-     * @return array ['digits' => int, 'rounding => int]
+     * @return array{digits: int, rounding: int}
      */
     public function getFraction(string $currencyCode): array
     {
@@ -102,6 +102,9 @@ public function getFraction(string $currencyCode): array
     protected function generateFractions(): void
     {
         $model = $this->cldrRepository->getModel('supplemental/supplementalData');
+        if (!$model) {
+            throw new \Exception('Missing model for supplemental/supplementalData', 1744411964);
+        }
         $currencyData = $model->getRawArray('currencyData');
 
         foreach ($currencyData['fractions'] as $fractionString) {
diff --git a/Neos.Flow/Classes/I18n/Cldr/Reader/DatesReader.php b/Neos.Flow/Classes/I18n/Cldr/Reader/DatesReader.php
index cc62041fb5..379ee695a0 100644
--- a/Neos.Flow/Classes/I18n/Cldr/Reader/DatesReader.php
+++ b/Neos.Flow/Classes/I18n/Cldr/Reader/DatesReader.php
@@ -108,7 +108,7 @@ class DatesReader
      * When length is set to zero, it means that corresponding format has no
      * maximal length.
      *
-     * @var array
+     * @var array<string,int>
      */
     protected static $maxLengthOfSubformats = [
         'G' => 5,
@@ -163,7 +163,7 @@ class DatesReader
      * are stored as one-element arrays in the same array. Order of elements
      * in array is important.
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $parsedFormats;
 
@@ -184,7 +184,7 @@ class DatesReader
      *     ...
      * );
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $parsedFormatsIndices;
 
@@ -194,7 +194,7 @@ class DatesReader
      * Locale tags are keys for this array. Values are arrays of literals, i.e.
      * names defined in months, days, quarters etc tags.
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $localizedLiterals;
 
@@ -255,7 +255,7 @@ public function shutdownObject()
      * @param Locale $locale
      * @param string $formatType A type of format (one of constant values)
      * @param string $formatLength A length of format (one of constant values)
-     * @return array An array representing parsed format
+     * @return array<mixed> An array representing parsed format
      * @throws Exception\InvalidDateTimeFormatException
      * @throws Exception\InvalidFormatLengthException
      * @throws Exception\InvalidFormatTypeException
@@ -273,6 +273,9 @@ public function parseFormatFromCldr(Locale $locale, string $formatType, string $
         }
 
         $model = $this->cldrRepository->getModelForLocale($locale);
+        if (!$model) {
+            throw new \Exception('Missing model for locale ' . $locale, 1744411881);
+        }
         $realFormatLength = $formatLength === '' || $formatLength === 'default' ? 'medium' : $formatLength;
 
         $format = $model->getElement('dates/calendars/calendar[@type="gregorian"]/' . $formatType . 'Formats/' . $formatType . 'FormatLength[@type="' . $realFormatLength . '"]/' . $formatType . 'Format/pattern');
@@ -301,7 +304,7 @@ public function parseFormatFromCldr(Locale $locale, string $formatType, string $
      * Returns parsed date or time format string provided as parameter.
      *
      * @param string $format Format string to parse
-     * @return array An array representing parsed format
+     * @return array<mixed> An array representing parsed format
      * @throws Exception\InvalidDateTimeFormatException
      */
     public function parseCustomFormat(string $format): array
@@ -319,7 +322,7 @@ public function parseCustomFormat(string $format): array
      * If array was not generated earlier, it will be generated and cached.
      *
      * @param Locale $locale
-     * @return array An array with localized literals
+     * @return array<mixed> An array with localized literals
      */
     public function getLocalizedLiteralsForLocale(Locale $locale): array
     {
@@ -328,6 +331,9 @@ public function getLocalizedLiteralsForLocale(Locale $locale): array
         }
 
         $model = $this->cldrRepository->getModelForLocale($locale);
+        if (!$model) {
+            throw new \Exception('Missing model for locale ' . $locale, 1744411830);
+        }
 
         $localizedLiterals['months'] = $this->parseLocalizedLiterals($model, 'month');
         $localizedLiterals['days'] = $this->parseLocalizedLiterals($model, 'day');
@@ -375,7 +381,7 @@ public static function validateFormatLength(string $formatLength): void
      * documentation for this class for details what is missing.
      *
      * @param string $format
-     * @return array Parsed format
+     * @return array<mixed> Parsed format
      * @throws Exception\InvalidDateTimeFormatException When subformat is longer than maximal value defined in $maxLengthOfSubformats property
      * @see DatesReader::$parsedFormats
      */
@@ -448,7 +454,7 @@ protected function parseFormat(string $format): array
      *
      * @param CldrModel $model CldrModel to read data from
      * @param string $literalType One of: month, day, quarter, dayPeriod
-     * @return array An array with localized literals for given type
+     * @return array<mixed> An array with localized literals for given type
      * @todo the two array checks should go away - but that needs clean input data
      */
     protected function parseLocalizedLiterals(CldrModel $model, string $literalType): array
@@ -481,7 +487,7 @@ protected function parseLocalizedLiterals(CldrModel $model, string $literalType)
      * Parses "eras" child of "dates" node and returns it's array representation.
      *
      * @param CldrModel $model CldrModel to read data from
-     * @return array An array with localized literals for "eras" node
+     * @return array<mixed> An array with localized literals for "eras" node
      */
     protected function parseLocalizedEras(CldrModel $model): array
     {
@@ -508,7 +514,7 @@ protected function parseLocalizedEras(CldrModel $model): array
      * @param string $format DateTime format
      * @param Locale $locale Locale to use
      * @param string $formatLength A length of format (full, long, medium, short) or 'default' to use default one from CLDR
-     * @return array Merged formats of date and time
+     * @return array<mixed> Merged formats of date and time
      * @throws Exception\InvalidDateTimeFormatException
      * @throws Exception\InvalidFormatLengthException
      * @throws Exception\InvalidFormatTypeException
@@ -538,7 +544,7 @@ protected function prepareDateAndTimeFormat(string $format, Locale $locale, stri
 
         if ($positionOfFirstPlaceholder !== 0) {
             // Add everything before placeholder as literal
-            $parsedFormat[] = [substr($format, 0, $positionOfFirstPlaceholder)];
+            $parsedFormat[] = [substr($format, 0, $positionOfFirstPlaceholder ?: 0)];
         }
 
         $parsedFormat = array_merge($parsedFormat, $firstParsedFormat);
diff --git a/Neos.Flow/Classes/I18n/Cldr/Reader/NumbersReader.php b/Neos.Flow/Classes/I18n/Cldr/Reader/NumbersReader.php
index 86bd26f4da..e38fe70cbb 100644
--- a/Neos.Flow/Classes/I18n/Cldr/Reader/NumbersReader.php
+++ b/Neos.Flow/Classes/I18n/Cldr/Reader/NumbersReader.php
@@ -33,6 +33,19 @@
  * - formatting numbers in other number systems than "latn"
  * - currency symbol substitution is simplified
  *
+ * @phpstan-type ParsedFormat array{
+ *     positivePrefix: string,
+ *     positiveSuffix: string,
+ *     negativePrefix: string,
+ *     negativeSuffix: string,
+ *     multiplier: int,
+ *     minDecimalDigits: int,
+ *     maxDecimalDigits: int,
+ *     minIntegerDigits: int,
+ *     primaryGroupingSize: int,
+ *     secondaryGroupingSize: int,
+ *     rounding: float
+ * }
  * @Flow\Scope("singleton")
  * @see http://www.unicode.org/reports/tr35/#Number_Elements
  * @see http://www.unicode.org/reports/tr35/#Number_Format_Patterns
@@ -126,7 +139,7 @@ class NumbersReader
      * localized during formatting (eg minus sign, percent etc), or other chars
      * which will be used as-is.
      *
-     * @var array
+     * @var array<string,ParsedFormat>
      */
     protected $parsedFormats;
 
@@ -147,7 +160,7 @@ class NumbersReader
      *     ...
      * );
      *
-     * @var array
+     * @var array<string,array<string,array<string,string>>>
      */
     protected $parsedFormatsIndices;
 
@@ -157,7 +170,7 @@ class NumbersReader
      * Locale identifiers are keys for this array. Values are arrays of symbols,
      * as defined in /ldml/numbers/symbols path in CLDR files.
      *
-     * @var array
+     * @var array<string,array<mixed>>
      */
     protected $localizedSymbols;
 
@@ -218,7 +231,7 @@ public function shutdownObject(): void
      * @param Locale $locale
      * @param string $formatType A type of format (one of constant values)
      * @param string $formatLength A length of format (one of constant values)
-     * @return array An array representing parsed format
+     * @return ParsedFormat An array representing parsed format
      * @throws Exception\InvalidFormatLengthException
      * @throws Exception\InvalidFormatTypeException
      * @throws Exception\UnableToFindFormatException When there is no proper format string in CLDR
@@ -245,6 +258,9 @@ public function parseFormatFromCldr(Locale $locale, string $formatType, string $
         }
 
         $model = $this->cldrRepository->getModelForLocale($locale);
+        if (!$model) {
+            throw new \Exception('Missing model for locale ' . $locale, 1744411694);
+        }
         $format = $model->getElement($formatPath);
 
         if (empty($format)) {
@@ -264,6 +280,9 @@ public function parseFormatFromCldr(Locale $locale, string $formatType, string $
     public function getDefaultNumberingSystem(Locale $locale): string
     {
         $model = $this->cldrRepository->getModelForLocale($locale);
+        if (!$model) {
+            throw new \Exception('Missing model for locale '. $locale, 1744411670);
+        }
         $result = $model->findNodesWithinPath('numbers', 'defaultNumberingSystem');
         return $result['defaultNumberingSystem'] ?? 'latn';
     }
@@ -272,7 +291,7 @@ public function getDefaultNumberingSystem(Locale $locale): string
      * Returns parsed date or time format string provided as parameter.
      *
      * @param string $format Format string to parse
-     * @return array An array representing parsed format
+     * @return ParsedFormat An array representing parsed format
      * @throws Exception\UnsupportedNumberFormatException
      */
     public function parseCustomFormat(string $format): array
@@ -294,15 +313,19 @@ public function parseCustomFormat(string $format): array
      * Symbols arrays for every requested locale are cached.
      *
      * @param Locale $locale
-     * @return array Symbols array
+     * @return array{decimal: string} Symbols array
      */
     public function getLocalizedSymbolsForLocale(Locale $locale): array
     {
         if (isset($this->localizedSymbols[(string)$locale])) {
+            /** @phpstan-ignore return.type (@todo enforce with extractor) */
             return $this->localizedSymbols[(string)$locale];
         }
 
         $model = $this->cldrRepository->getModelForLocale($locale);
+        if (!$model) {
+            throw new \Exception('missing model for locale ' . $locale, 1744411617);
+        }
         return $this->localizedSymbols[(string)$locale] = $model->getRawArray('numbers/symbols');
     }
 
@@ -343,7 +366,7 @@ public static function validateFormatLength(string $formatLength): void
      * documentation for this class for details what is missing.
      *
      * @param string $format
-     * @return array Parsed format
+     * @return ParsedFormat Parsed format
      * @throws Exception\UnsupportedNumberFormatException When unsupported format characters encountered
      * @see NumbersReader::$parsedFormats
      */
@@ -403,7 +426,7 @@ protected function parseFormat(string $format): array
 
         if (preg_match(self::PATTERN_MATCH_ROUNDING, $format, $matches) === 1) {
             $parsedFormat['rounding'] = (float)$matches[1];
-            $format = preg_replace('/[1-9]/', '0', $format);
+            $format = preg_replace('/[1-9]/', '0', $format) ?: '';
         }
 
         if (($positionOfDecimalSeparator = strpos($format, '.')) !== false) {
diff --git a/Neos.Flow/Classes/I18n/Cldr/Reader/PluralsReader.php b/Neos.Flow/Classes/I18n/Cldr/Reader/PluralsReader.php
index f33289ff5b..41feb1adb1 100644
--- a/Neos.Flow/Classes/I18n/Cldr/Reader/PluralsReader.php
+++ b/Neos.Flow/Classes/I18n/Cldr/Reader/PluralsReader.php
@@ -16,6 +16,7 @@
 use Neos\Flow\Annotations as Flow;
 use Neos\Cache\Frontend\VariableFrontend;
 use Neos\Flow\I18n\Cldr\CldrRepository;
+use Neos\Flow\I18n\Cldr\Reader\Exception\InvalidPluralRuleException;
 use Neos\Flow\I18n\Locale;
 
 /**
@@ -86,7 +87,7 @@ class PluralsReader
      *   subrule in chain. If current subrule is a last one (or only one), this
      *   element is set to false.
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $rulesets;
 
@@ -94,7 +95,7 @@ class PluralsReader
      * An associative array holding information which ruleset is used by given
      * locale. One or more locales can use the same ruleset.
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $rulesetsIndices;
 
@@ -223,7 +224,7 @@ public function getPluralForm($quantity, Locale $locale): string
      * Returns array of plural forms available for particular locale.
      *
      * @param Locale $locale Locale to return plural forms for
-     * @return array Plural forms' names (one, zero, two, few, many, other) available for language set in this model
+     * @return array<mixed> Plural forms' names (one, zero, two, few, many, other) available for language set in this model
      */
     public function getPluralForms(Locale $locale): array
     {
@@ -254,6 +255,9 @@ public function getPluralForms(Locale $locale): array
     protected function generateRulesets(): void
     {
         $model = $this->cldrRepository->getModel('supplemental/plurals');
+        if (!$model) {
+            throw new InvalidPluralRuleException('Missing plural rule model for supplemental/plurals', 1744411434);
+        }
         $pluralRulesSet = $model->getRawArray('plurals');
 
         $index = 0;
@@ -300,7 +304,7 @@ protected function generateRulesets(): void
      * $rulesets property for details).
      *
      * @param string $rule
-     * @return array Parsed rule
+     * @return array<mixed> Parsed rule
      * @throws Exception\InvalidPluralRuleException When plural rule does not match regexp pattern
      */
     protected function parseRule(string $rule): array
@@ -319,12 +323,12 @@ protected function parseRule(string $rule): array
 
                 $condition = [$matchedSubrule[3], (int)$matchedSubrule[4]];
                 if (!in_array($matchedSubrule[3], ['is', 'isnot'], true)) {
-                    $condition[2] = (int)$matchedSubrule[5];
+                    $condition[2] = (int)($matchedSubrule[5] ?? 0);
                 }
 
                 $subrule['condition'] = $condition;
 
-                if (isset($matchedSubrule[6]) && ($matchedSubrule[6] === 'and' || $matchedSubrule[6] === 'or')) {
+                if (isset($matchedSubrule[6])) {
                     $subrule['logicalOperator'] = $matchedSubrule[6];
                 } else {
                     $subrule['logicalOperator'] = false;
diff --git a/Neos.Flow/Classes/I18n/Configuration.php b/Neos.Flow/Classes/I18n/Configuration.php
index 5a8352c26e..d30ffc5e6a 100644
--- a/Neos.Flow/Classes/I18n/Configuration.php
+++ b/Neos.Flow/Classes/I18n/Configuration.php
@@ -24,12 +24,12 @@ class Configuration
     protected $defaultLocale;
 
     /**
-     * @var Locale
+     * @var ?Locale
      */
     protected $currentLocale;
 
     /**
-     * @var array
+     * @var array{strict: bool, order: array<int,string>}
      */
     protected $fallbackRule = ['strict' => false, 'order' => []];
 
@@ -103,9 +103,9 @@ public function getCurrentLocale()
      * Here is an example:
      *   array('strict' => false, 'order' => array('dk', 'za'))
      *
-     * @param array $fallbackRule
+     * @param array{strict?: bool, order?: array<int,string>} $fallbackRule
      */
-    public function setFallbackRule(array $fallbackRule)
+    public function setFallbackRule(array $fallbackRule): void
     {
         if (!array_key_exists('order', $fallbackRule)) {
             throw new \InvalidArgumentException('The given fallback rule did not contain an order element.', 1406710671);
@@ -119,7 +119,7 @@ public function setFallbackRule(array $fallbackRule)
     /**
      * Returns the current fallback rule.
      *
-     * @return array
+     * @return array<mixed>
      * @see setFallbackRule()
      */
     public function getFallbackRule()
diff --git a/Neos.Flow/Classes/I18n/EelHelper/TranslationHelper.php b/Neos.Flow/Classes/I18n/EelHelper/TranslationHelper.php
index dc71fa5b4c..2d14e01764 100644
--- a/Neos.Flow/Classes/I18n/EelHelper/TranslationHelper.php
+++ b/Neos.Flow/Classes/I18n/EelHelper/TranslationHelper.php
@@ -34,7 +34,7 @@ class TranslationHelper implements ProtectedContextAwareInterface
      *
      * @param string $id Id to use for finding translation (trans-unit id in XLIFF)
      * @param string $originalLabel The original translation value (the untranslated source string).
-     * @param array $arguments Array of numerically indexed or named values to be inserted into placeholders. Have a look at the internationalization documentation in the definitive guide for details.
+     * @param array<mixed> $arguments Array of numerically indexed or named values to be inserted into placeholders. Have a look at the internationalization documentation in the definitive guide for details.
      * @param string $source Name of file with translations
      * @param string $package Target package key. If not set, the current package key will be used
      * @param mixed $quantity A number to find plural form for (float or int), NULL to not use plural forms
@@ -98,10 +98,10 @@ public function allowsCallOfMethod($methodName)
      * translated label.
      *
      * @param string $id Id to use for finding translation (trans-unit id in XLIFF)
-     * @param string $originalLabel The original translation value (the untranslated source string).
-     * @param array $arguments Numerically indexed array of values to be inserted into placeholders
+     * @param ?string $originalLabel The original translation value (the untranslated source string).
+     * @param array<mixed> $arguments Numerically indexed array of values to be inserted into placeholders
      * @param string|null $source Name of file with translations, defaults to 'Main'
-     * @param string $package Target package key. If not set, the current package key will be used
+     * @param ?string $package Target package key. If not set, the current package key will be used
      * @param mixed $quantity A number to find plural form for (float or int), NULL to not use plural forms
      * @param string $locale An identifier of locale to use (NULL for use the default locale)
      * @return string|null Translated label or source label / ID key
@@ -111,11 +111,15 @@ protected function translateByExplicitlyPassedOrderedArguments($id, $originalLab
         $translationParameterToken = $this->createTranslationParameterToken($id);
         $source = $source === null ? 'Main' : str_replace('.', '/', $source);
         $translationParameterToken
-            ->value($originalLabel)
             ->arguments($arguments)
             ->source($source)
-            ->package($package)
             ->quantity($quantity);
+        if ($originalLabel) {
+            $translationParameterToken->value($originalLabel);
+        }
+        if ($package) {
+            $translationParameterToken->package($package);
+        }
 
         if ($locale !== null) {
             $translationParameterToken->locale($locale);
diff --git a/Neos.Flow/Classes/I18n/EelHelper/TranslationParameterToken.php b/Neos.Flow/Classes/I18n/EelHelper/TranslationParameterToken.php
index 71db0f3f0a..d43dd117bb 100644
--- a/Neos.Flow/Classes/I18n/EelHelper/TranslationParameterToken.php
+++ b/Neos.Flow/Classes/I18n/EelHelper/TranslationParameterToken.php
@@ -36,7 +36,7 @@ class TranslationParameterToken implements ProtectedContextAwareInterface
     /**
      * Key/Value store to keep the collected parameters
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $parameters = [];
 
@@ -61,7 +61,7 @@ public function __construct($id = null, $value = null)
      *
      * @param Translator $translator
      */
-    public function injectTranslator(Translator $translator)
+    public function injectTranslator(Translator $translator): void
     {
         $this->translator = $translator;
     }
@@ -93,7 +93,7 @@ public function value($value)
     /**
      * Set the arguments.
      *
-     * @param array $arguments Numerically indexed array of values to be inserted into placeholders
+     * @param array<mixed> $arguments Numerically indexed array of values to be inserted into placeholders
      * @return TranslationParameterToken
      */
     public function arguments(array $arguments)
@@ -160,13 +160,14 @@ public function locale($locale)
     /**
      * Translate according to currently collected parameters
      *
-     * @param array $overrides An associative array to override the collected parameters
+     * @param array<mixed> $overrides An associative array to override the collected parameters
      * @return string|null
      * @throws IndexOutOfBoundsException
      * @throws InvalidFormatPlaceholderException
      */
     public function translate(array $overrides = [])
     {
+        /** @phpstan-ignore function.resultUnused (whatever, @todo fixme) */
         array_replace_recursive($this->parameters, $overrides);
 
         $id = $this->parameters['id'] ?? null;
@@ -182,7 +183,7 @@ public function translate(array $overrides = [])
         }
 
         $translation = $this->translator->translateById($id, $arguments, $quantity, $locale, $source, $package);
-        if ($translation === null && $value !== null) {
+        if ($translation === null) {
             return $this->translator->translateByOriginalLabel($value, $arguments, $quantity, $locale, $source, $package);
         }
 
diff --git a/Neos.Flow/Classes/I18n/FormatResolver.php b/Neos.Flow/Classes/I18n/FormatResolver.php
index c9ab23df2b..010f0324c1 100644
--- a/Neos.Flow/Classes/I18n/FormatResolver.php
+++ b/Neos.Flow/Classes/I18n/FormatResolver.php
@@ -58,7 +58,7 @@ class FormatResolver
     /**
      * Array of concrete formatters used by this class.
      *
-     * @var array<FormatterInterface>
+     * @var array<string,FormatterInterface>
      */
     protected $formatters;
 
@@ -91,7 +91,7 @@ public function injectLocalizationService(I18n\Service $localizationService)
      * specific and they are directly passed to the formatter class.
      *
      * @param string $textWithPlaceholders String message with placeholder(s)
-     * @param array $arguments An array of values to replace placeholders with
+     * @param array<string,mixed> $arguments An array of values to replace placeholders with
      * @param Locale $locale Locale to use (NULL for default one)
      * @return string The $text with placeholders resolved
      * @throws Exception\InvalidFormatPlaceholderException When encountered incorrectly formatted placeholder
@@ -169,8 +169,14 @@ protected function getFormatter($formatterType)
         if ($foundFormatter === false) {
             if ($this->objectManager->isRegistered($formatterType)) {
                 $possibleClassName = $formatterType;
+                if (!class_exists($possibleClassName)) {
+                    throw new \Exception('Invalid formatter ' . $possibleClassName, 1744413028);
+                }
             } else {
                 $possibleClassName = sprintf('Neos\Flow\I18n\Formatter\%sFormatter', ucfirst($formatterType));
+                if (!class_exists($possibleClassName)) {
+                    throw new \Exception('Invalid formatter ' . $possibleClassName, 1744413028);
+                }
                 if (!$this->objectManager->isRegistered($possibleClassName)) {
                     throw new Exception\UnknownFormatterException('Could not find formatter for "' . $formatterType . '".', 1278057791);
                 }
@@ -180,6 +186,9 @@ protected function getFormatter($formatterType)
             }
             $foundFormatter = $this->objectManager->get($possibleClassName);
         }
+        if (!$foundFormatter instanceof FormatterInterface) {
+            throw new \Exception('No valid formatter found, got ' . get_class($foundFormatter), 1744412948);
+        }
 
         $this->formatters[$formatterType] = $foundFormatter;
         return $foundFormatter;
diff --git a/Neos.Flow/Classes/I18n/Formatter/DatetimeFormatter.php b/Neos.Flow/Classes/I18n/Formatter/DatetimeFormatter.php
index 2cb876c528..27346332f1 100644
--- a/Neos.Flow/Classes/I18n/Formatter/DatetimeFormatter.php
+++ b/Neos.Flow/Classes/I18n/Formatter/DatetimeFormatter.php
@@ -48,7 +48,7 @@ public function injectDatesReader(DatesReader $datesReader)
      *
      * @param mixed $value Formatter-specific variable to format (can be integer, \DateTime, etc)
      * @param Locale $locale Locale to use
-     * @param array $styleProperties Integer-indexed array of formatter-specific style properties (can be empty)
+     * @param array<mixed> $styleProperties Integer-indexed array of formatter-specific style properties (can be empty)
      * @return string String representation of $value provided, or (string)$value
      * @api
      */
@@ -157,8 +157,8 @@ public function formatDateTime(\DateTimeInterface $dateTime, Locale $locale, $fo
      * are replaced with elements from $localizedLiterals array.
      *
      * @param \DateTimeInterface $dateTime PHP object representing particular point in time
-     * @param array $parsedFormat An array describing format (as in $parsedFormats property)
-     * @param array $localizedLiterals An array with literals to use (as in $localizedLiterals property)
+     * @param array<mixed> $parsedFormat An array describing format (as in $parsedFormats property)
+     * @param array<mixed> $localizedLiterals An array with literals to use (as in $localizedLiterals property)
      * @return string Formatted date / time
      */
     protected function doFormattingWithParsedFormat(\DateTimeInterface $dateTime, array $parsedFormat, array $localizedLiterals)
@@ -191,7 +191,7 @@ protected function doFormattingWithParsedFormat(\DateTimeInterface $dateTime, ar
      *
      * @param \DateTimeInterface $dateTime PHP object representing particular point in time
      * @param string $subformat One element of format string (e.g., 'yyyy', 'mm', etc)
-     * @param array $localizedLiterals Array of date / time literals from CLDR
+     * @param array<string,mixed> $localizedLiterals Array of date / time literals from CLDR
      * @return string Formatted part of date / time
      * @throws InvalidArgumentException When $subformat use symbol that is not recognized
      * @see \Neos\Flow\I18n\Cldr\Reader\DatesReader
@@ -210,25 +210,25 @@ protected function doFormattingForSubpattern(\DateTimeInterface $dateTime, $subf
                 if ($hour === 12) {
                     $hour = 0;
                 }
-                return $this->padString($hour, $formatLengthOfSubformat);
+                return $this->padString((string)$hour, $formatLengthOfSubformat);
             case 'k':
                 $hour = (int)($dateTime->format('G'));
                 if ($hour === 0) {
                     $hour = 24;
                 }
-                return $this->padString($hour, $formatLengthOfSubformat);
+                return $this->padString((string)$hour, $formatLengthOfSubformat);
             case 'a':
                 return $localizedLiterals['dayPeriods']['format']['wide'][$dateTime->format('a')];
             case 'm':
-                return $this->padString((int)($dateTime->format('i')), $formatLengthOfSubformat);
+                return $this->padString($dateTime->format('i'), $formatLengthOfSubformat);
             case 's':
-                return $this->padString((int)($dateTime->format('s')), $formatLengthOfSubformat);
+                return $this->padString($dateTime->format('s'), $formatLengthOfSubformat);
             case 'S':
-                return (string)round($dateTime->format('u'), $formatLengthOfSubformat);
+                return (string)round((int)$dateTime->format('u'), $formatLengthOfSubformat);
             case 'd':
                 return $this->padString($dateTime->format('j'), $formatLengthOfSubformat);
             case 'D':
-                return $this->padString(((int)$dateTime->format('z') + 1), $formatLengthOfSubformat);
+                return $this->padString((string)((int)$dateTime->format('z') + 1), $formatLengthOfSubformat);
             case 'F':
                 return (string)(int)(((int)$dateTime->format('j') + 6) / 7);
             case 'M':
@@ -236,7 +236,7 @@ protected function doFormattingForSubpattern(\DateTimeInterface $dateTime, $subf
                 $month = (int)$dateTime->format('n');
                 $formatType = ($subformat[0] === 'L') ? 'stand-alone' : 'format';
                 if ($formatLengthOfSubformat <= 2) {
-                    return $this->padString($month, $formatLengthOfSubformat);
+                    return $this->padString((string)$month, $formatLengthOfSubformat);
                 } elseif ($formatLengthOfSubformat === 3) {
                     return $localizedLiterals['months'][$formatType]['abbreviated'][$month];
                 } elseif ($formatLengthOfSubformat === 4) {
@@ -250,7 +250,7 @@ protected function doFormattingForSubpattern(\DateTimeInterface $dateTime, $subf
                 if ($formatLengthOfSubformat === 2) {
                     $year %= 100;
                 }
-                return $this->padString($year, $formatLengthOfSubformat);
+                return $this->padString((string)$year, $formatLengthOfSubformat);
             case 'E':
                 $day = strtolower($dateTime->format('D'));
                 if ($formatLengthOfSubformat <= 3) {
@@ -270,7 +270,7 @@ protected function doFormattingForSubpattern(\DateTimeInterface $dateTime, $subf
                 $quarter = (int)($dateTime->format('n') / 3.1) + 1;
                 $formatType = ($subformat[0] === 'q') ? 'stand-alone' : 'format';
                 if ($formatLengthOfSubformat <= 2) {
-                    return $this->padString($quarter, $formatLengthOfSubformat);
+                    return $this->padString((string)$quarter, $formatLengthOfSubformat);
                 } elseif ($formatLengthOfSubformat === 3) {
                     return $localizedLiterals['quarters'][$formatType]['abbreviated'][$quarter];
                 } else {
diff --git a/Neos.Flow/Classes/I18n/Formatter/FormatterInterface.php b/Neos.Flow/Classes/I18n/Formatter/FormatterInterface.php
index 608cce9ab3..a03ceee643 100644
--- a/Neos.Flow/Classes/I18n/Formatter/FormatterInterface.php
+++ b/Neos.Flow/Classes/I18n/Formatter/FormatterInterface.php
@@ -24,7 +24,7 @@ interface FormatterInterface
      *
      * @param mixed $value Formatter-specific variable to format (can be integer, \DateTime, etc)
      * @param Locale $locale Locale to use
-     * @param array $styleProperties Integer-indexed array of formatter-specific style properties (can be empty)
+     * @param array<mixed> $styleProperties Integer-indexed array of formatter-specific style properties (can be empty)
      * @return string String representation of $value provided, or (string)$value
      * @api
      */
diff --git a/Neos.Flow/Classes/I18n/Formatter/NumberFormatter.php b/Neos.Flow/Classes/I18n/Formatter/NumberFormatter.php
index a70ea6688e..69a411f1df 100644
--- a/Neos.Flow/Classes/I18n/Formatter/NumberFormatter.php
+++ b/Neos.Flow/Classes/I18n/Formatter/NumberFormatter.php
@@ -58,7 +58,7 @@ public function injectCurrencyReader(CurrencyReader $currencyReader)
      *
      * @param mixed $value Formatter-specific variable to format (can be integer, \DateTime, etc)
      * @param Locale $locale Locale to use
-     * @param array $styleProperties Integer-indexed array of formatter-specific style properties (can be empty)
+     * @param array<mixed> $styleProperties Integer-indexed array of formatter-specific style properties (can be empty)
      * @return string String representation of $value provided, or (string)$value
      * @api
      */
@@ -181,12 +181,12 @@ public function formatCurrencyNumber($number, Locale $locale, $currency, $format
      * as defined in CLDR specification.
      *
      * @param mixed $number Float or int, can be negative, can be NaN or infinite
-     * @param array $parsedFormat An array describing format (as in $parsedFormats property)
-     * @param array $symbols An array with symbols to use (as in $localeSymbols property)
+     * @param array<mixed>|false $parsedFormat An array describing format (as in $parsedFormats property)
+     * @param array<mixed> $symbols An array with symbols to use (as in $localeSymbols property)
      * @param string $currency Currency symbol to be inserted into formatted number (if applicable)
      * @return string Formatted number. Will return string-casted version of $number if pattern is false
      */
-    protected function doFormattingWithParsedFormat($number, array $parsedFormat, array $symbols, $currency = null)
+    protected function doFormattingWithParsedFormat($number, array|false $parsedFormat, array $symbols, $currency = null)
     {
         if ($parsedFormat === false) {
             return (string)$number;
@@ -232,8 +232,8 @@ protected function doFormattingWithParsedFormat($number, array $parsedFormat, ar
         $integerPart = str_pad($integerPart, $parsedFormat['minIntegerDigits'], '0', STR_PAD_LEFT);
 
         if ($parsedFormat['primaryGroupingSize'] > 0 && strlen($integerPart) > $parsedFormat['primaryGroupingSize']) {
-            $primaryGroupOfIntegerPart = substr($integerPart, - $parsedFormat['primaryGroupingSize']);
-            $restOfIntegerPart = substr($integerPart, 0, - $parsedFormat['primaryGroupingSize']);
+            $primaryGroupOfIntegerPart = substr($integerPart, - (int)$parsedFormat['primaryGroupingSize']);
+            $restOfIntegerPart = substr($integerPart, 0, - (int)$parsedFormat['primaryGroupingSize']);
 
             // Pad the numbers with spaces from the left, so the length of the string is a multiply of secondaryGroupingSize (and str_split() can split on equal parts)
             $padLengthToGetEvenSize = (int)((strlen($restOfIntegerPart) + $parsedFormat['secondaryGroupingSize'] - 1) / $parsedFormat['secondaryGroupingSize']) * $parsedFormat['secondaryGroupingSize'];
diff --git a/Neos.Flow/Classes/I18n/Locale.php b/Neos.Flow/Classes/I18n/Locale.php
index 8f67d4371b..11b7a237fc 100644
--- a/Neos.Flow/Classes/I18n/Locale.php
+++ b/Neos.Flow/Classes/I18n/Locale.php
@@ -89,11 +89,8 @@ class Locale
      * @throws Exception\InvalidLocaleIdentifierException If the locale identifier is not valid
      * @api
      */
-    public function __construct($localeIdentifier)
+    public function __construct(string $localeIdentifier)
     {
-        if (!is_string($localeIdentifier)) {
-            throw new \InvalidArgumentException('A locale identifier must be of type string, ' . gettype($localeIdentifier) . ' given.', 1221216120);
-        }
         if (preg_match(self::PATTERN_MATCH_LOCALEIDENTIFIER, $localeIdentifier, $matches) !== 1) {
             throw new Exception\InvalidLocaleIdentifierException('"' . $localeIdentifier . '" is not a valid locale identifier.', 1221137814);
         }
diff --git a/Neos.Flow/Classes/I18n/LocaleTypeConverter.php b/Neos.Flow/Classes/I18n/LocaleTypeConverter.php
index 7c938a0126..0df231151f 100644
--- a/Neos.Flow/Classes/I18n/LocaleTypeConverter.php
+++ b/Neos.Flow/Classes/I18n/LocaleTypeConverter.php
@@ -43,7 +43,7 @@ class LocaleTypeConverter extends AbstractTypeConverter
      *
      * @param string $source the locale string
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface $configuration
      * @return Locale
      * @api
diff --git a/Neos.Flow/Classes/I18n/Parser/DatetimeParser.php b/Neos.Flow/Classes/I18n/Parser/DatetimeParser.php
index 7b3a6fad52..0c2d3a4aa8 100644
--- a/Neos.Flow/Classes/I18n/Parser/DatetimeParser.php
+++ b/Neos.Flow/Classes/I18n/Parser/DatetimeParser.php
@@ -127,10 +127,10 @@ public function parseDateAndTime($dateAndTimeToParse, I18n\Locale $locale, $form
      * Parses date and / or time using parsed format, in strict or lenient mode.
      *
      * @param string $datetimeToParse Date/time to be parsed
-     * @param array $parsedFormat Parsed format (from DatesReader)
-     * @param array $localizedLiterals Array of date / time literals from CLDR
+     * @param array<mixed> $parsedFormat Parsed format (from DatesReader)
+     * @param array<mixed> $localizedLiterals Array of date / time literals from CLDR
      * @param boolean $strictMode Work mode (strict when true, lenient when false)
-     * @return mixed Array of parsed date and / or time elements, false on failure
+     * @return array<string,mixed>|false Array of parsed date and / or time elements, false on failure
      */
     protected function doParsingWithParsedFormat($datetimeToParse, array $parsedFormat, array $localizedLiterals, $strictMode)
     {
@@ -141,9 +141,9 @@ protected function doParsingWithParsedFormat($datetimeToParse, array $parsedForm
      * Parses date and / or time in strict mode.
      *
      * @param string $datetimeToParse Date/time to be parsed
-     * @param array $parsedFormat Format parsed by DatesReader
-     * @param array $localizedLiterals Array of date / time literals from CLDR
-     * @return array|false Array of parsed date and / or time elements, false on failure
+     * @param array<mixed> $parsedFormat Format parsed by DatesReader
+     * @param array<mixed> $localizedLiterals Array of date / time literals from CLDR
+     * @return array<string,mixed>|false Array of parsed date and / or time elements, false on failure
      * @throws InvalidArgumentException When unexpected symbol found in format
      * @see DatesReader
      */
@@ -341,10 +341,9 @@ protected function doParsingInStrictMode($datetimeToParse, array $parsedFormat,
      * - some format fallback substitutions can be done (eg. 'Jan' for 'January')
      *
      * @param string $datetimeToParse Date/time to be parsed
-     * @param array $parsedFormat Format parsed by DatesReader
-     * @param array $localizedLiterals Array of date / time literals from CLDR
-     * @return array Array of parsed date and / or time elements (can be array of NULLs if nothing was parsed)
-     * @throws Exception\InvalidParseStringException
+     * @param array<mixed> $parsedFormat Format parsed by DatesReader
+     * @param array<mixed> $localizedLiterals Array of date / time literals from CLDR
+     * @return array<string,mixed> Array of parsed date and / or time elements (can be array of NULLs if nothing was parsed)
      * @throws InvalidArgumentException When unexpected symbol found in format
      * @see DatesReader
      */
@@ -403,7 +402,7 @@ protected function doParsingInLenientMode($datetimeToParse, array $parsedFormat,
                             $hour = $this->extractNumberAndGetPosition($datetimeToParse, $position);
                         }
                         if ($hour >= 0 && $hour <= 23) {
-                            $numberOfCharactersToRemove = $position + strlen($hour);
+                            $numberOfCharactersToRemove = $position + strlen((string)$hour);
                             $datetimeElements['hour'] = (int)$hour;
                             break;
                         }
@@ -533,9 +532,10 @@ protected function doParsingInLenientMode($datetimeToParse, array $parsedFormat,
                             }
                         }
 
-                        $timezone = $matches[0];
+                        /** @var string $timezone */
+                        $timezone = $matches[0] ?? null;
                         $numberOfCharactersToRemove = strpos($datetimeToParse, $timezone) + strlen($timezone);
-                        $datetimeElements['timezone'] = $matches[0];
+                        $datetimeElements['timezone'] = $timezone;
                         break;
                     case 'D':
                     case 'F':
diff --git a/Neos.Flow/Classes/I18n/Parser/NumberParser.php b/Neos.Flow/Classes/I18n/Parser/NumberParser.php
index dae3ef6be1..fee40f5298 100644
--- a/Neos.Flow/Classes/I18n/Parser/NumberParser.php
+++ b/Neos.Flow/Classes/I18n/Parser/NumberParser.php
@@ -66,7 +66,12 @@ public function injectNumbersReader(NumbersReader $numbersReader)
      */
     public function parseNumberWithCustomPattern($numberToParse, $format, Locale $locale, $strictMode = true)
     {
-        return $this->doParsingWithParsedFormat($numberToParse, $this->numbersReader->parseCustomFormat($format), $this->numbersReader->getLocalizedSymbolsForLocale($locale), $strictMode);
+        return $this->doParsingWithParsedFormat(
+            $numberToParse,
+            $this->numbersReader->parseCustomFormat($format),
+            $this->numbersReader->getLocalizedSymbolsForLocale($locale),
+            $strictMode
+        );
     }
 
     /**
@@ -82,7 +87,16 @@ public function parseNumberWithCustomPattern($numberToParse, $format, Locale $lo
     public function parseDecimalNumber($numberToParse, Locale $locale, $formatLength = NumbersReader::FORMAT_LENGTH_DEFAULT, $strictMode = true)
     {
         NumbersReader::validateFormatLength($formatLength);
-        return $this->doParsingWithParsedFormat($numberToParse, $this->numbersReader->parseFormatFromCldr($locale, NumbersReader::FORMAT_TYPE_DECIMAL, $formatLength), $this->numbersReader->getLocalizedSymbolsForLocale($locale), $strictMode);
+        return $this->doParsingWithParsedFormat(
+            $numberToParse,
+            $this->numbersReader->parseFormatFromCldr(
+                $locale,
+                NumbersReader::FORMAT_TYPE_DECIMAL,
+                $formatLength
+            ),
+            $this->numbersReader->getLocalizedSymbolsForLocale($locale),
+            $strictMode
+        );
     }
 
     /**
@@ -98,15 +112,24 @@ public function parseDecimalNumber($numberToParse, Locale $locale, $formatLength
     public function parsePercentNumber($numberToParse, Locale $locale, $formatLength = NumbersReader::FORMAT_LENGTH_DEFAULT, $strictMode = true)
     {
         NumbersReader::validateFormatLength($formatLength);
-        return $this->doParsingWithParsedFormat($numberToParse, $this->numbersReader->parseFormatFromCldr($locale, NumbersReader::FORMAT_TYPE_PERCENT, $formatLength), $this->numbersReader->getLocalizedSymbolsForLocale($locale), $strictMode);
+        return $this->doParsingWithParsedFormat(
+            $numberToParse,
+            $this->numbersReader->parseFormatFromCldr(
+                $locale,
+                NumbersReader::FORMAT_TYPE_PERCENT,
+                $formatLength
+            ),
+            $this->numbersReader->getLocalizedSymbolsForLocale($locale),
+            $strictMode
+        );
     }
 
     /**
      * Parses number using parsed format, in strict or lenient mode.
      *
      * @param string $numberToParse Number to be parsed
-     * @param array $parsedFormat Parsed format (from NumbersReader)
-     * @param array $localizedSymbols An array with symbols to use
+     * @param array{negativePrefix?: string, negativeSuffix?: string, multiplier: int} $parsedFormat Parsed format (from NumbersReader)
+     * @param array{decimal: string} $localizedSymbols An array with symbols to use
      * @param boolean $strictMode Work mode (strict when true, lenient when false)
      * @return mixed Parsed float number or false on failure
      */
@@ -122,8 +145,8 @@ protected function doParsingWithParsedFormat($numberToParse, array $parsedFormat
      * and if any of them is not fullfiled, parsing fails (false is returned).
      *
      * @param string $numberToParse Number to be parsed
-     * @param array $parsedFormat Parsed format (from NumbersReader)
-     * @param array $localizedSymbols An array with symbols to use
+     * @param array<string,mixed> $parsedFormat Parsed format (from NumbersReader)
+     * @param array<string,mixed> $localizedSymbols An array with symbols to use
      * @return mixed Parsed float number or false on failure
      */
     protected function doParsingInStrictMode($numberToParse, array $parsedFormat, array $localizedSymbols)
@@ -184,7 +207,7 @@ protected function doParsingInStrictMode($numberToParse, array $parsedFormat, ar
 
             $numberToParse = str_replace([$localizedSymbols['group'], $localizedSymbols['decimal']], ['', '.'], $numberToParse);
 
-            $positionOfDecimalSeparator = strpos($numberToParse, '.');
+            $positionOfDecimalSeparator = strpos($numberToParse, '.') ?: 0;
             $integerPart = substr($numberToParse, 0, $positionOfDecimalSeparator);
             $decimalPart = substr($numberToParse, $positionOfDecimalSeparator + 1);
         }
@@ -239,8 +262,8 @@ protected function doParsingInStrictMode($numberToParse, array $parsedFormat, ar
      * 7. Try to match negative suffix after last digit
      *
      * @param string $numberToParse Number to be parsed
-     * @param array $parsedFormat Parsed format (from NumbersReader)
-     * @param array $localizedSymbols An array with symbols to use
+     * @param array{negativePrefix?: string, negativeSuffix?: string, multiplier: int} $parsedFormat Parsed format (from NumbersReader)
+     * @param array{decimal: string} $localizedSymbols An array with symbols to use
      * @return mixed Parsed float number or false on failure
      */
     protected function doParsingInLenientMode($numberToParse, array $parsedFormat, array $localizedSymbols)
diff --git a/Neos.Flow/Classes/I18n/Service.php b/Neos.Flow/Classes/I18n/Service.php
index c4aa342a3e..a00fc841a9 100644
--- a/Neos.Flow/Classes/I18n/Service.php
+++ b/Neos.Flow/Classes/I18n/Service.php
@@ -27,7 +27,7 @@
 class Service
 {
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $settings;
 
@@ -65,7 +65,7 @@ class Service
     protected $localeBasePath = 'resource://';
 
     /**
-     * @param array $settings
+     * @param array<string,mixed> $settings
      * @return void
      */
     public function injectSettings(array $settings)
@@ -120,9 +120,9 @@ public function getConfiguration()
      * any change.
      *
      * @param string $pathAndFilename Path to the file
-     * @param Locale $locale Desired locale of localized file
+     * @param ?Locale $locale Desired locale of localized file
      * @param boolean $strict Whether to match only provided locale (true) or search for best-matching locale (false)
-     * @return array Path to the localized file (or $filename when no localized file was found) and the matched locale
+     * @return array{0: string, 1: Locale} Path to the localized file (or $filename when no localized file was found) and the matched locale
      * @see Configuration::setFallbackRule()
      * @api
      */
@@ -134,7 +134,7 @@ public function getLocalizedFilename($pathAndFilename, ?Locale $locale = null, $
 
         $filename = basename($pathAndFilename);
         if ((strpos($filename, '.')) !== false) {
-            $dotPosition = strrpos($pathAndFilename, '.');
+            $dotPosition = strrpos($pathAndFilename, '.') ?: 0;
             $pathAndFilenameWithoutExtension = substr($pathAndFilename, 0, $dotPosition);
             $extension = substr($pathAndFilename, $dotPosition);
         } else {
@@ -175,7 +175,7 @@ public function getLocalizedFilename($pathAndFilename, ?Locale $locale = null, $
      * @param string $path Base directory to the translation files
      * @param string $sourceName name of the translation source
      * @param Locale $locale Desired locale of XLIFF file
-     * @return array Path to the localized file (or $filename when no localized file was found) and the matched locale
+     * @return array{0: string|false, 1: Locale} Path to the localized file (or $filename when no localized file was found) and the matched locale
      * @see Configuration::setFallbackRule()
      * @api
      */
@@ -198,7 +198,7 @@ public function getXliffFilenameAndPath($path, $sourceName, ?Locale $locale = nu
      * Build a chain of locale objects according to the fallback rule and
      * the available locales.
      * @param Locale $locale
-     * @return array
+     * @return array<string,Locale>
      */
     public function getLocaleChain(Locale $locale)
     {
diff --git a/Neos.Flow/Classes/I18n/Translator.php b/Neos.Flow/Classes/I18n/Translator.php
index c4938afddd..94bd7be90b 100644
--- a/Neos.Flow/Classes/I18n/Translator.php
+++ b/Neos.Flow/Classes/I18n/Translator.php
@@ -113,7 +113,7 @@ public function injectPluralsReader(Cldr\Reader\PluralsReader $pluralsReader)
      * If no $locale is provided, default system locale will be used.
      *
      * @param string $originalLabel Untranslated message
-     * @param array $arguments An array of values to replace placeholders with
+     * @param array<string,mixed> $arguments An array of values to replace placeholders with
      * @param mixed $quantity A number to find plural form for (float or int), NULL to not use plural forms
      * @param Locale $locale Locale to use (NULL for default one)
      * @param string $sourceName Name of file with translations, base path is $packageKey/Resources/Private/Locale/Translations/
@@ -170,7 +170,7 @@ public function translateByOriginalLabel($originalLabel, array $arguments = [],
      * be chosen and used to choose correct translation variant.
      *
      * @param string $labelId Key to use for finding translation
-     * @param array $arguments An array of values to replace placeholders with
+     * @param array<mixed> $arguments An array of values to replace placeholders with
      * @param mixed $quantity A number to find plural form for (float or int), NULL to not use plural forms
      * @param Locale $locale Locale to use (NULL for default one)
      * @param string $sourceName Name of file with translations, base path is $packageKey/Resources/Private/Locale/Translations/
diff --git a/Neos.Flow/Classes/I18n/Utility.php b/Neos.Flow/Classes/I18n/Utility.php
index be8ada326b..33ba019a42 100644
--- a/Neos.Flow/Classes/I18n/Utility.php
+++ b/Neos.Flow/Classes/I18n/Utility.php
@@ -123,7 +123,9 @@ public static function extractLocaleTagFromDirectory($directory)
         $directoryParts = explode('/', rtrim($directory, '/'));
         $lastDirectoryPart = array_pop($directoryParts);
 
-        if ($lastDirectoryPart !== null && preg_match(Locale::PATTERN_MATCH_LOCALEIDENTIFIER, $lastDirectoryPart) === 1) {
+        if (
+            preg_match(Locale::PATTERN_MATCH_LOCALEIDENTIFIER, $lastDirectoryPart) === 1
+        ) {
             return $lastDirectoryPart;
         }
 
diff --git a/Neos.Flow/Classes/I18n/Xliff/Model/FileAdapter.php b/Neos.Flow/Classes/I18n/Xliff/Model/FileAdapter.php
index ce650b0ead..1ea3d0fea6 100644
--- a/Neos.Flow/Classes/I18n/Xliff/Model/FileAdapter.php
+++ b/Neos.Flow/Classes/I18n/Xliff/Model/FileAdapter.php
@@ -29,6 +29,8 @@
  * numbers. Leaving it this way in .xlf files, makes it possible to easily convert
  * them to .po (e.g. using xliff2po from Translation Toolkit), edit with Poedit,
  * and convert back to .xlf without any information loss (using po2xliff).
+ *
+ * @phpstan-type XliffRecord array{fileIdentifier: string, sourceLocale?: Locale, translationUnits?: array<string,array<int,array{source: string, target: string}>>}
  */
 class FileAdapter
 {
@@ -39,9 +41,9 @@ class FileAdapter
     protected $i18nLogger;
 
     /**
-     * @var array
+     * @var XliffRecord
      */
-    protected $fileData = [];
+    protected array $fileData;
 
     /**
      * @var Locale
@@ -50,7 +52,7 @@ class FileAdapter
 
 
     /**
-     * @param array $fileData
+     * @param XliffRecord $fileData
      * @param Locale $requestedLocale
      */
     public function __construct(array $fileData, Locale $requestedLocale)
@@ -69,7 +71,7 @@ public function __construct(array $fileData, Locale $requestedLocale)
      *
      * @param string $source Label in original language ("source" tag in XLIFF)
      * @param integer $pluralFormIndex Index of plural form to use (starts with 0)
-     * @return mixed Translated label or false on failure
+     * @return string|false Translated label or false on failure
      */
     public function getTargetBySource($source, $pluralFormIndex = 0)
     {
@@ -117,21 +119,14 @@ public function getTargetByTransUnitId($transUnitId, $pluralFormIndex = 0)
             return false;
         }
 
-        if (!isset($this->fileData['translationUnits'][$transUnitId][$pluralFormIndex]['target'])) {
-            $this->i18nLogger->log(
-                'The target translation was empty for the trans-unit element with the id "' . $transUnitId . '" and the plural form index "' . $pluralFormIndex . '" in ' . $this->fileData['fileIdentifier'],
-                LOG_DEBUG
-            );
-        }
-
         return $this->fileData['translationUnits'][$transUnitId][$pluralFormIndex]['target'];
     }
 
     /**
-     * @return array
+     * @return array<string,array<int,array{source: string, target: string}>>
      */
     public function getTranslationUnits(): array
     {
-        return $this->fileData['translationUnits'];
+        return $this->fileData['translationUnits'] ?? [];
     }
 }
diff --git a/Neos.Flow/Classes/I18n/Xliff/Service/XliffFileProvider.php b/Neos.Flow/Classes/I18n/Xliff/Service/XliffFileProvider.php
index 771f57bdbd..9a35c94174 100644
--- a/Neos.Flow/Classes/I18n/Xliff/Service/XliffFileProvider.php
+++ b/Neos.Flow/Classes/I18n/Xliff/Service/XliffFileProvider.php
@@ -25,6 +25,7 @@
  * A provider service for XLIFF file objects within the application
  *
  * @Flow\Scope("singleton")
+ * @phpstan-import-type XliffRecord from FileAdapter
  */
 class XliffFileProvider
 {
@@ -65,7 +66,7 @@ class XliffFileProvider
     protected $xliffBasePath = 'Private/Translations/';
 
     /**
-     * @var array
+     * @var array<string,array<string,XliffRecord>>
      */
     protected $files = [];
 
@@ -94,7 +95,7 @@ public function initializeObject()
     /**
      * @param string $fileId
      * @param Locale $locale
-     * @return array
+     * @return XliffRecord
      * @todo Add XLIFF 2.0 support
      */
     public function getMergedFileData($fileId, Locale $locale): array
@@ -126,7 +127,7 @@ public function getMergedFileData($fileId, Locale $locale): array
 
     /**
      * @param string $translationPath
-     * @param array $parsedData
+     * @param array{fileIdentifier: string, sourceLocale?: Locale, translationUnits?: array<string,array<int,array{source: string, target: string}>>} $parsedData
      * @param string $fileId
      * @param string $defaultPackageName
      * @return void
@@ -135,7 +136,7 @@ protected function readDirectoryRecursively(string $translationPath, array & $pa
     {
         foreach (Files::readDirectoryRecursively($translationPath) as $filePath) {
             $defaultSource = trim(str_replace($translationPath, '', $filePath), '/');
-            $defaultSource = substr($defaultSource, 0, strrpos($defaultSource, '.'));
+            $defaultSource = substr($defaultSource, 0, strrpos($defaultSource, '.') ?: 0);
 
             $relevantOffset = null;
             $documentVersion = null;
@@ -161,7 +162,8 @@ function (\XMLReader $file, $offset, $version) use ($fileId, &$documentVersion,
                 $xliffParser = $this->getParser($documentVersion);
                 if ($xliffParser) {
                     $fileData = $xliffParser->getFileDataFromDocument($filePath, $relevantOffset);
-                    $parsedData = Arrays::arrayMergeRecursiveOverrule($parsedData, $fileData);
+                    /** @phpstan-ignore parameterByRef.type (arrayMergeRecursiveOverrule will not reduce the array shape) */
+                    $parsedData = Arrays::arrayMergeRecursiveOverrule($parsedData, $fileData ?: []);
                 }
             }
         }
@@ -186,7 +188,6 @@ public function getParser($documentVersion)
         switch ($documentVersion) {
             case '1.2':
                 return new V12XliffParser();
-                break;
             default:
                 return null;
         }
diff --git a/Neos.Flow/Classes/I18n/Xliff/V12/XliffParser.php b/Neos.Flow/Classes/I18n/Xliff/V12/XliffParser.php
index 092686bbfb..30d18a4691 100644
--- a/Neos.Flow/Classes/I18n/Xliff/V12/XliffParser.php
+++ b/Neos.Flow/Classes/I18n/Xliff/V12/XliffParser.php
@@ -37,7 +37,7 @@ class XliffParser extends AbstractXmlParser
      * Returns array representation of XLIFF data, starting from a root node.
      *
      * @param \SimpleXMLElement $root A root node
-     * @return array An array representing parsed XLIFF
+     * @return array<int,array{sourceLocale: Locale, translationUnits?: array<string,array<int,array{source: string, target: string}>>}> An array representing parsed XLIFF
      * @throws InvalidXliffDataException
      * @todo Support "approved" attribute
      */
@@ -54,7 +54,7 @@ protected function doParsingFromRoot(\SimpleXMLElement $root): array
 
     /**
      * @param \SimpleXMLElement $file
-     * @return array
+     * @return array{sourceLocale: Locale, translationUnits?: array<string,array<int,array{source: string, target: string}>>}
      * @throws InvalidXliffDataException
      */
     protected function getFileData(\SimpleXMLElement $file): array
@@ -110,7 +110,7 @@ protected function getFileData(\SimpleXMLElement $file): array
                         if (!empty($parsedTranslationElement)) {
                             if (isset($translationElement->{'trans-unit'}[0]['id'])) {
                                 $id = (string)$translationElement->{'trans-unit'}[0]['id'];
-                                $id = substr($id, 0, strpos($id, '['));
+                                $id = substr($id, 0, strpos($id, '[') ?: 0);
                             } else {
                                 throw new InvalidXliffDataException('A trans-unit tag without id attribute was found, validate your XLIFF files.', 1329399258);
                             }
@@ -128,7 +128,7 @@ protected function getFileData(\SimpleXMLElement $file): array
     /**
      * @param string $sourcePath
      * @param mixed $fileOffset
-     * @return array|null
+     * @return array{sourceLocale: Locale, translationUnits?: array<string,array<int,array{source: string, target: string}>>}|null
      * @throws InvalidXliffDataException
      * @throws InvalidXmlFileException
      */
diff --git a/Neos.Flow/Classes/Log/PsrLoggerFactory.php b/Neos.Flow/Classes/Log/PsrLoggerFactory.php
index 5825f0300c..0d473677a1 100644
--- a/Neos.Flow/Classes/Log/PsrLoggerFactory.php
+++ b/Neos.Flow/Classes/Log/PsrLoggerFactory.php
@@ -23,14 +23,14 @@ class PsrLoggerFactory implements PsrLoggerFactoryInterface
     protected $instances = [];
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $configuration = [];
 
     /**
      * PsrLoggerFactory constructor.
      *
-     * @param array $configuration
+     * @param array<mixed> $configuration
      */
     public function __construct(array $configuration = [])
     {
@@ -69,7 +69,7 @@ public function get(string $identifier): \Psr\Log\LoggerInterface
     /**
      * Create a new instance of this PsrLoggerFactory
      *
-     * @param array $configuration
+     * @param array<mixed> $configuration
      * @return PsrLoggerFactory
      * @api
      */
@@ -81,7 +81,7 @@ public static function create(array $configuration): PsrLoggerFactory
     /**
      * Instantiate all configured backends
      *
-     * @param array $configuration
+     * @param array<mixed> $configuration
      * @return BackendInterface[]
      * @throws \Exception
      */
@@ -101,7 +101,7 @@ protected function instantiateBackends(array $configuration): array
      * Instantiate a backend based on configuration.
      *
      * @param string $class
-     * @param array $options
+     * @param array<mixed> $options
      * @return BackendInterface
      * @throws \Exception
      */
diff --git a/Neos.Flow/Classes/Log/PsrLoggerFactoryInterface.php b/Neos.Flow/Classes/Log/PsrLoggerFactoryInterface.php
index 2c16210fe9..6599925cab 100644
--- a/Neos.Flow/Classes/Log/PsrLoggerFactoryInterface.php
+++ b/Neos.Flow/Classes/Log/PsrLoggerFactoryInterface.php
@@ -30,7 +30,7 @@ public function get(string $identifier);
      * Reminder for super low level things like this, the Bootstrap class has
      * some static properties for you.
      *
-     * @param array $configuration
+     * @param array<mixed> $configuration
      * @return static
      * @api
      */
diff --git a/Neos.Flow/Classes/Log/ThrowableStorage/FileStorage.php b/Neos.Flow/Classes/Log/ThrowableStorage/FileStorage.php
index 4fe0cd53a4..4d28b91c6c 100644
--- a/Neos.Flow/Classes/Log/ThrowableStorage/FileStorage.php
+++ b/Neos.Flow/Classes/Log/ThrowableStorage/FileStorage.php
@@ -10,7 +10,6 @@
 use Neos\Flow\Log\ThrowableStorageInterface;
 use Neos\Flow\ObjectManagement\ObjectManagerInterface;
 use Neos\Utility\Files;
-use Psr\Http\Message\RequestInterface;
 
 /**
  * Stores detailed information about throwables into files.
@@ -53,7 +52,7 @@ class FileStorage implements ThrowableStorageInterface
     /**
      * Factory method to get an instance.
      *
-     * @param array $options
+     * @param array{storagePath?: string, maximumThrowableDumpAge?: int, maximumThrowableDumpCount: ?int} $options
      * @return ThrowableStorageInterface
      */
     public static function createWithOptions(array $options): ThrowableStorageInterface
@@ -88,14 +87,13 @@ public function __construct(string $storagePath, int $maximumThrowableDumpAge, i
             }
 
             $bootstrap = Bootstrap::$staticObjectManager->get(Bootstrap::class);
-            /* @var Bootstrap $bootstrap */
             $requestHandler = $bootstrap->getActiveRequestHandler();
             if (!$requestHandler instanceof HttpRequestHandlerInterface) {
                 return $output;
             }
 
             $request = $requestHandler->getHttpRequest();
-            $output .= PHP_EOL . 'HTTP REQUEST:' . PHP_EOL . ($request instanceof RequestInterface ? RequestInformationHelper::renderRequestInformation($request) : '[request was empty]') . PHP_EOL;
+            $output .= PHP_EOL . 'HTTP REQUEST:' . PHP_EOL . RequestInformationHelper::renderRequestInformation($request) . PHP_EOL;
             $output .= PHP_EOL . 'PHP PROCESS:' . PHP_EOL . 'Inode: ' . getmyinode() . PHP_EOL . 'PID: ' . getmypid() . PHP_EOL . 'UID: ' . getmyuid() . PHP_EOL . 'GID: ' . getmygid() . PHP_EOL . 'User: ' . get_current_user() . PHP_EOL;
 
             return $output;
@@ -137,7 +135,7 @@ public function setBacktraceRenderer(\Closure $backtraceRenderer)
      * Exception #<code> in <line> of <file>: <message> - See also: <dumpFilename>
      *
      * @param \Throwable $throwable
-     * @param array $additionalData
+     * @param array<mixed> $additionalData
      * @return string Informational message about the stored throwable
      */
     public function logThrowable(\Throwable $throwable, array $additionalData = [])
@@ -177,14 +175,14 @@ public function logThrowable(\Throwable $throwable, array $additionalData = [])
     protected function generateUniqueReferenceCode()
     {
         $timestamp = $_SERVER['REQUEST_TIME'] ?? time();
-        return date('YmdHis', $timestamp) . substr(md5(rand()), 0, 6);
+        return date('YmdHis', $timestamp) . substr(md5((string)rand()), 0, 6);
     }
 
     /**
      * Get current error post mortem informations with support for error chaining
      *
      * @param \Throwable $error
-     * @param array $additionalData
+     * @param array<mixed> $additionalData
      * @return string
      */
     protected function renderErrorInfo(\Throwable $error, array $additionalData = [])
@@ -226,7 +224,7 @@ protected function getErrorLogMessage(\Throwable $error)
             $errorCodeString = ' [' . $error->getCode() . ']';
         }
         $backTrace = $error->getTrace();
-        $line = isset($backTrace[0]['line']) ? ' in line ' . $backTrace[0]['line'] . ' of ' . $backTrace[0]['file'] : '';
+        $line = isset($backTrace[0]['line']) ? ' in line ' . $backTrace[0]['line'] . ' of ' . ($backTrace[0]['file'] ?? 'unknown') : '';
 
         return 'Exception' . $errorCodeString . $line . ': ' . $error->getMessage();
     }
@@ -234,7 +232,7 @@ protected function getErrorLogMessage(\Throwable $error)
     /**
      * Renders background information about the circumstances of the exception.
      *
-     * @param array $backtrace
+     * @param array<mixed> $backtrace
      * @return string
      */
     protected function renderBacktrace($backtrace)
@@ -281,7 +279,7 @@ protected function cleanupThrowableDumps(): void
 
         if ($this->maximumThrowableDumpCount > 0) {
             // this returns alphabetically ordered, so oldest first, as we have a date/time in the name
-            $existingDumps = glob(Files::concatenatePaths([$this->storagePath, '*']));
+            $existingDumps = glob(Files::concatenatePaths([$this->storagePath, '*'])) ?: [];
             $existingDumpsCount = count($existingDumps);
             if ($existingDumpsCount > $this->maximumThrowableDumpCount) {
                 $dumpsToRemove = array_slice($existingDumps, 0, $existingDumpsCount - $this->maximumThrowableDumpCount);
diff --git a/Neos.Flow/Classes/Log/ThrowableStorageInterface.php b/Neos.Flow/Classes/Log/ThrowableStorageInterface.php
index 747d20e055..3fb6a2763d 100644
--- a/Neos.Flow/Classes/Log/ThrowableStorageInterface.php
+++ b/Neos.Flow/Classes/Log/ThrowableStorageInterface.php
@@ -13,7 +13,7 @@ interface ThrowableStorageInterface
      *
      * Note that throwable storages must work without proxy so all dependencies need to be resolved manually or via options.
      *
-     * @param array $options
+     * @param array<mixed> $options
      * @return ThrowableStorageInterface
      */
     public static function createWithOptions(array $options): ThrowableStorageInterface;
@@ -25,7 +25,7 @@ public static function createWithOptions(array $options): ThrowableStorageInterf
      * can be logged or displayed as needed.
      *
      * @param \Throwable $throwable The throwable to log
-     * @param array $additionalData Additional data to log
+     * @param array<mixed> $additionalData Additional data to log
      * @return string Informational message about the stored throwable
      * @api
      */
diff --git a/Neos.Flow/Classes/Log/Utility/LogEnvironment.php b/Neos.Flow/Classes/Log/Utility/LogEnvironment.php
index 8d3dec8c52..38e19301a3 100644
--- a/Neos.Flow/Classes/Log/Utility/LogEnvironment.php
+++ b/Neos.Flow/Classes/Log/Utility/LogEnvironment.php
@@ -23,7 +23,7 @@
 abstract class LogEnvironment
 {
     /**
-     * @var array
+     * @var array<string,true>
      */
     protected static $packageKeys = [];
 
@@ -38,7 +38,7 @@ abstract class LogEnvironment
      * in an log method call.
      *
      * @param string $methodName
-     * @return array
+     * @return array<string,array{packageKey: ?string, className: string, methodName: string}>
      */
     public static function fromMethodName(string $methodName): array
     {
@@ -62,9 +62,9 @@ public static function fromMethodName(string $methodName): array
 
     /**
      * @param string $className
-     * @return string
+     * @return ?string
      */
-    protected static function getPackageKeyFromClassName(string $className): string
+    protected static function getPackageKeyFromClassName(string $className): ?string
     {
         $packageKeys = static::getPackageKeys();
         $classPathArray = explode('\\', $className);
@@ -86,7 +86,7 @@ protected static function getPackageKeyFromClassName(string $className): string
     }
 
     /**
-     * @return array
+     * @return array<string,true>
      * @Flow\CompileStatic
      */
     protected static function getPackageKeys(): array
diff --git a/Neos.Flow/Classes/Monitor/ChangeDetectionStrategy/ModificationTimeStrategy.php b/Neos.Flow/Classes/Monitor/ChangeDetectionStrategy/ModificationTimeStrategy.php
index 39a239c735..70f3e46746 100644
--- a/Neos.Flow/Classes/Monitor/ChangeDetectionStrategy/ModificationTimeStrategy.php
+++ b/Neos.Flow/Classes/Monitor/ChangeDetectionStrategy/ModificationTimeStrategy.php
@@ -31,7 +31,7 @@ class ModificationTimeStrategy implements ChangeDetectionStrategyInterface, Stra
     protected $cache;
 
     /**
-     * @var array
+     * @var array<string,int>
      */
     protected $filesAndModificationTimes = [];
 
@@ -61,7 +61,7 @@ public function injectCache(StringFrontend $cache)
     public function setFileMonitor(FileMonitor $fileMonitor)
     {
         $this->fileMonitor = $fileMonitor;
-        $this->filesAndModificationTimes = json_decode($this->cache->get($this->fileMonitor->getIdentifier() . '_filesAndModificationTimes'), true);
+        $this->filesAndModificationTimes = json_decode($this->cache->get($this->fileMonitor->getIdentifier() . '_filesAndModificationTimes') ?: '', true);
     }
 
     /**
@@ -120,7 +120,7 @@ public function setFileDeleted($pathAndFilename)
     public function shutdownObject()
     {
         if ($this->modificationTimesChanged === true) {
-            $this->cache->set($this->fileMonitor->getIdentifier() . '_filesAndModificationTimes', json_encode($this->filesAndModificationTimes));
+            $this->cache->set($this->fileMonitor->getIdentifier() . '_filesAndModificationTimes', json_encode($this->filesAndModificationTimes, JSON_THROW_ON_ERROR));
         }
     }
 }
diff --git a/Neos.Flow/Classes/Monitor/FileMonitor.php b/Neos.Flow/Classes/Monitor/FileMonitor.php
index 948e8ce772..883f37a753 100644
--- a/Neos.Flow/Classes/Monitor/FileMonitor.php
+++ b/Neos.Flow/Classes/Monitor/FileMonitor.php
@@ -55,33 +55,33 @@ class FileMonitor
     protected $cache;
 
     /**
-     * @var array
+     * @var array<int,string>
      */
     protected $monitoredFiles = [];
 
     /**
-     * @var array
+     * @var array<string,?string>
      */
     protected $monitoredDirectories = [];
 
     /**
      * Changed files for this monitor
      *
-     * @var array
+     * @var array<string,int>|null
      */
     protected $changedFiles = null;
 
     /**
      * The changed paths for this monitor
      *
-     * @var array
+     * @var array<string,int>|null
      */
     protected $changedPaths = null;
 
     /**
      * Array of directories and files that were cached on the last run.
      *
-     * @var array|null
+     * @var array<string,array<string,int>>|null
      */
     protected $directoriesAndFiles = null;
 
@@ -106,6 +106,9 @@ public function __construct($identifier)
     public static function createFileMonitorAtBoot($identifier, Bootstrap $bootstrap)
     {
         $fileMonitorCache = $bootstrap->getEarlyInstance(CacheManager::class)->getCache('Flow_Monitor');
+        if (!$fileMonitorCache instanceof StringFrontend) {
+            throw new \Exception('The file monitor cache must have a string frontend', 1744387394);
+        }
 
         // The change detector needs to be instantiated and registered manually because
         // it has a complex dependency (cache) but still needs to be a singleton.
@@ -135,7 +138,7 @@ public function injectChangeDetectionStrategy(ChangeDetectionStrategyInterface $
     }
 
     /**
-     * Injects the Singal Slot Dispatcher because classes of the Monitor subpackage cannot be proxied by the AOP
+     * Injects the Signal Slot Dispatcher because classes of the Monitor subpackage cannot be proxied by the AOP
      * framework because it is not initialized at the time the monitoring is used.
      *
      * @param Dispatcher $signalDispatcher The Signal Slot Dispatcher
@@ -187,11 +190,8 @@ public function getIdentifier()
      * @throws \InvalidArgumentException
      * @api
      */
-    public function monitorFile($pathAndFilename)
+    public function monitorFile(string $pathAndFilename)
     {
-        if (!is_string($pathAndFilename)) {
-            throw new \InvalidArgumentException('String expected, ' . gettype($pathAndFilename), ' given.', 1231171809);
-        }
         $pathAndFilename = Files::getUnixStylePath($pathAndFilename);
         if (array_search($pathAndFilename, $this->monitoredFiles) === false) {
             $this->monitoredFiles[] = $pathAndFilename;
@@ -203,16 +203,13 @@ public function monitorFile($pathAndFilename)
      * All files in these directories will be monitored too.
      *
      * @param string $path Absolute path of the directory to monitor
-     * @param string $filenamePattern A pattern for filenames to consider for file monitoring (regular expression)
+     * @param ?string $filenamePattern A pattern for filenames to consider for file monitoring (regular expression)
      * @return void
      * @throws \InvalidArgumentException
      * @api
      */
-    public function monitorDirectory($path, $filenamePattern = null)
+    public function monitorDirectory(string $path, $filenamePattern = null)
     {
-        if (!is_string($path)) {
-            throw new \InvalidArgumentException('String expected, ' . gettype($path), ' given.', 1231171810);
-        }
         $path = Files::getNormalizedPath(Files::getUnixStylePath($path));
         if (!array_key_exists($path, $this->monitoredDirectories)) {
             $this->monitoredDirectories[$path] = $filenamePattern;
@@ -222,7 +219,7 @@ public function monitorDirectory($path, $filenamePattern = null)
     /**
      * Returns a list of all monitored files
      *
-     * @return array A list of paths and filenames of monitored files
+     * @return array<string> A list of paths and filenames of monitored files
      * @api
      */
     public function getMonitoredFiles()
@@ -233,7 +230,7 @@ public function getMonitoredFiles()
     /**
      * Returns a list of all monitored directories
      *
-     * @return array A list of paths of monitored directories
+     * @return array<string> A list of paths of monitored directories
      * @api
      */
     public function getMonitoredDirectories()
@@ -265,14 +262,17 @@ public function detectChanges()
             }
             $this->directoriesAndFiles = null;
         }
-
+        /** @phpstan-ignore argument.type (never null) */
         $changedFileCount = count($this->changedFiles);
+        /** @phpstan-ignore argument.type (never null) */
         $changedPathCount = count($this->changedPaths);
 
         if ($changedFileCount > 0) {
+            /** @phpstan-ignore argument.type (never null) */
             $this->emitFilesHaveChanged($this->identifier, $this->changedFiles);
         }
         if ($changedPathCount > 0) {
+            /** @phpstan-ignore argument.type (never null) */
             $this->emitDirectoriesHaveChanged($this->identifier, $this->changedPaths);
         }
         if ($changedFileCount > 0 || $changedPathCount) {
@@ -284,7 +284,7 @@ public function detectChanges()
      * Detect changes for one of the monitored paths.
      *
      * @param string $path
-     * @param string $filenamePattern
+     * @param ?string $filenamePattern
      * @return boolean true if any changes were detected in this path
      */
     protected function detectChangesOnPath($path, $filenamePattern)
@@ -341,7 +341,7 @@ protected function detectChangesOnPath($path, $filenamePattern)
      * Read a monitored directory recursively, taking into account filename patterns
      *
      * @param string $path The path of a monitored directory
-     * @param string $filenamePattern
+     * @param ?string $filenamePattern
      * @return \Generator<string> A generator returning filenames with full path
      */
     protected function readMonitoredDirectoryRecursively($path, $filenamePattern)
@@ -377,7 +377,7 @@ protected function readMonitoredDirectoryRecursively($path, $filenamePattern)
     protected function loadDetectedDirectoriesAndFiles()
     {
         if ($this->directoriesAndFiles === null) {
-            $this->directoriesAndFiles = json_decode($this->cache->get($this->identifier . '_directoriesAndFiles'), true);
+            $this->directoriesAndFiles = json_decode($this->cache->get($this->identifier . '_directoriesAndFiles') ?: '', true);
             if (!is_array($this->directoriesAndFiles)) {
                 $this->directoriesAndFiles = [];
             }
@@ -391,12 +391,12 @@ protected function loadDetectedDirectoriesAndFiles()
      */
     protected function saveDetectedDirectoriesAndFiles()
     {
-        $this->cache->set($this->identifier . '_directoriesAndFiles', json_encode($this->directoriesAndFiles));
+        $this->cache->set($this->identifier . '_directoriesAndFiles', json_encode($this->directoriesAndFiles, JSON_THROW_ON_ERROR));
     }
 
     /**
      * @param string $path
-     * @param array $files
+     * @param array<string,int> $files
      * @return void
      */
     protected function setDetectedFilesForPath($path, array $files)
@@ -407,8 +407,8 @@ protected function setDetectedFilesForPath($path, array $files)
     /**
      * Detects changes in the given list of files and emits signals if necessary.
      *
-     * @param array $pathAndFilenames A list of full path and filenames of files to check
-     * @return array An array of changed files (key = path and filenmae) and their status (value)
+     * @param array<int,string> $pathAndFilenames A list of full path and filenames of files to check
+     * @return array<string,int> An array of changed files (key = path and filenmae) and their status (value)
      */
     protected function detectChangedFiles(array $pathAndFilenames)
     {
@@ -426,7 +426,7 @@ protected function detectChangedFiles(array $pathAndFilenames)
      * Signalizes that the specified file has changed
      *
      * @param string $monitorIdentifier Name of the monitor which detected the change
-     * @param array $changedFiles An array of changed files (key = path and filename) and their status (value)
+     * @param array<string,int> $changedFiles An array of changed files (key = path and filename) and their status (value)
      * @return void
      * @api
      */
@@ -439,7 +439,7 @@ protected function emitFilesHaveChanged($monitorIdentifier, array $changedFiles)
      * Signalizes that the specified directory has changed
      *
      * @param string $monitorIdentifier Name of the monitor which detected the change
-     * @param array $changedDirectories An array of changed directories (key = path) and their status (value)
+     * @param array<string,int> $changedDirectories An array of changed directories (key = path) and their status (value)
      * @return void
      * @api
      */
diff --git a/Neos.Flow/Classes/Mvc/ActionRequest.php b/Neos.Flow/Classes/Mvc/ActionRequest.php
index d3fb98ff25..fb62ef4972 100644
--- a/Neos.Flow/Classes/Mvc/ActionRequest.php
+++ b/Neos.Flow/Classes/Mvc/ActionRequest.php
@@ -72,7 +72,7 @@ class ActionRequest
     /**
      * The arguments for this request. They must be only simple types, no
      * objects allowed.
-     * @var array
+     * @var array<mixed>
      */
     protected $arguments = [];
 
@@ -81,14 +81,14 @@ class ActionRequest
      * All framework-internal arguments start with double underscore (__),
      * and are only used from within the framework. Not for user consumption.
      * Internal Arguments can be objects, in contrast to public arguments.
-     * @var array
+     * @var array<mixed>
      */
     protected $internalArguments = [];
 
     /**
      * Arguments and configuration for plugins – including widgets – which are
      * sub controllers to the controller referred to by this request.
-     * @var array
+     * @var array<mixed>
      */
     protected $pluginArguments = [];
 
@@ -158,15 +158,10 @@ public function createSubRequest(): ActionRequest
     /**
      * Returns the parent request
      *
-     * @return ActionRequest
      * @api
      */
     public function getParentRequest(): ?ActionRequest
     {
-        if ($this->isMainRequest()) {
-            return null;
-        }
-
         return $this->parentRequest;
     }
 
@@ -205,7 +200,7 @@ public function getMainRequest(): ActionRequest
      * Checks if this request is the uppermost ActionRequest, just one below the
      * HTTP request.
      *
-     * @phpstan-assert-if-true null $this->getParentRequest()
+     * @phpstan-assert-if-true null $this->parentRequest
      * @return boolean
      * @api
      */
@@ -300,10 +295,14 @@ public function setControllerObjectName(string $unknownCasedControllerObjectName
             throw new UnknownObjectException('The object "' . $unknownCasedControllerObjectName . '" is not registered.', 1268844071);
         }
 
-        $this->controllerPackageKey = $this->objectManager->getPackageKeyByObjectName($controllerObjectName);
+        $controllerPackageKey = $this->objectManager->getPackageKeyByObjectName($controllerObjectName);
+        if (!$controllerPackageKey) {
+            throw new \Exception('Failed to resolve package key for controller ' . $controllerObjectName, 1744329205);
+        }
+        $this->controllerPackageKey = $controllerPackageKey;
 
         $matches = [];
-        $subject = substr($controllerObjectName, strlen($this->controllerPackageKey) + 1);
+        $subject = substr($controllerObjectName, strlen($controllerPackageKey) + 1);
         preg_match(
             '/
 			^(
@@ -318,7 +317,7 @@ public function setControllerObjectName(string $unknownCasedControllerObjectName
         );
 
         $this->controllerSubpackageKey = $matches['subpackageKey'] ?? null;
-        $this->controllerName = $matches['controllerName'];
+        $this->controllerName = $matches['controllerName'] ?? '';
     }
 
     /**
@@ -444,6 +443,9 @@ public function getControllerActionName(): string
         $controllerObjectName = $this->getControllerObjectName();
         if ($controllerObjectName !== '' && ($this->controllerActionName === strtolower($this->controllerActionName))) {
             $controllerClassName = $this->objectManager->getClassNameByObjectName($controllerObjectName);
+            if ($controllerClassName === false) {
+                throw new \Exception('Could not resolve controller class for ' . $controllerObjectName);
+            }
             $lowercaseActionMethodName = $this->controllerActionName . 'action';
             foreach (get_class_methods($controllerClassName) as $existingMethodName) {
                 if (strtolower($existingMethodName) === $lowercaseActionMethodName) {
@@ -512,7 +514,7 @@ public function setArgument(string $argumentName, $value): void
      * Returns the value of the specified argument
      *
      * @param string $argumentName Name of the argument
-     * @return string|array Value of the argument
+     * @return string|array<mixed> Value of the argument
      * @throws Exception\NoSuchArgumentException if such an argument does not exist
      * @api
      */
@@ -542,7 +544,7 @@ public function hasArgument(string $argumentName): bool
      * The arguments array will be reset therefore any arguments
      * which existed before will be overwritten!
      *
-     * @param array $arguments An array of argument names and their values
+     * @param array<mixed> $arguments An array of argument names and their values
      * @return void
      * @throws Exception\InvalidArgumentNameException if an argument name is not a string
      * @throws Exception\InvalidArgumentTypeException if an argument value is an object
@@ -560,7 +562,7 @@ public function setArguments(array $arguments): void
     /**
      * Returns an Array of arguments and their values
      *
-     * @return array Array of arguments and their values (which may be arguments and values as well)
+     * @return array<mixed> Array of arguments and their values (which may be arguments and values as well)
      * @api
      */
     public function getArguments(): array
@@ -586,7 +588,7 @@ public function getInternalArgument(string $argumentName)
      * Returns the internal arguments of the request, that is, all arguments whose
      * name starts with two underscores.
      *
-     * @return array
+     * @return array<mixed>
      */
     public function getInternalArguments(): array
     {
@@ -621,7 +623,7 @@ public function getArgumentNamespace(): string
     /**
      * Returns an array of plugin argument configurations
      *
-     * @return array
+     * @return array<mixed>
      */
     public function getPluginArguments(): array
     {
diff --git a/Neos.Flow/Classes/Mvc/ActionRequestFactory.php b/Neos.Flow/Classes/Mvc/ActionRequestFactory.php
index e09d7eda10..134b658836 100644
--- a/Neos.Flow/Classes/Mvc/ActionRequestFactory.php
+++ b/Neos.Flow/Classes/Mvc/ActionRequestFactory.php
@@ -12,7 +12,7 @@ class ActionRequestFactory
 {
     /**
      * @param ServerRequestInterface $httpRequest
-     * @param array $additionalArguments
+     * @param array<mixed> $additionalArguments
      * @return ActionRequest
      * @throws Exception\InvalidActionNameException
      * @throws Exception\InvalidArgumentNameException
@@ -33,7 +33,7 @@ public function createActionRequest(ServerRequestInterface $httpRequest, array $
 
     /**
      * @param ServerRequestInterface $httpRequest
-     * @return array
+     * @return array<mixed>
      */
     protected function mergeHttpRequestArguments(ServerRequestInterface $httpRequest): array
     {
@@ -50,9 +50,9 @@ protected function mergeHttpRequestArguments(ServerRequestInterface $httpRequest
     }
 
     /**
-     * @param array $arguments
-     * @param array $additionalArguments
-     * @return array
+     * @param array<mixed> $arguments
+     * @param array<mixed> $additionalArguments
+     * @return array<mixed>
      */
     protected function mergeHttpRequestArgumentsWithAdditionalArguments(array $arguments, array $additionalArguments): array
     {
diff --git a/Neos.Flow/Classes/Mvc/ActionResponse.php b/Neos.Flow/Classes/Mvc/ActionResponse.php
index 1600075a9f..29e80c6b51 100644
--- a/Neos.Flow/Classes/Mvc/ActionResponse.php
+++ b/Neos.Flow/Classes/Mvc/ActionResponse.php
@@ -80,7 +80,7 @@ final class ActionResponse
     protected $content;
 
     /**
-     * @var UriInterface
+     * @var ?UriInterface
      */
     protected $redirectUri;
 
@@ -95,7 +95,7 @@ final class ActionResponse
     protected $statusCode;
 
     /**
-     * @var string
+     * @var ?string
      */
     protected $contentType;
 
@@ -105,7 +105,7 @@ final class ActionResponse
     protected $cookies = [];
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $headers = [];
 
@@ -204,7 +204,7 @@ public function deleteCookie(string $cookieName): void
      * This behaviour is unsafe and partially unspecified: https://github.com/neos/flow-development-collection/issues/2492
      *
      * @param string $headerName The name of the header to set
-     * @param array|string|\DateTime $headerValue An array of values or a single value for the specified header field
+     * @param array<mixed>|string|\DateTime $headerValue An array of values or a single value for the specified header field
      * @return void
      */
     public function setHttpHeader(string $headerName, $headerValue): void
@@ -224,7 +224,7 @@ public function setHttpHeader(string $headerName, $headerValue): void
      * This behaviour is unsafe and partially unspecified: https://github.com/neos/flow-development-collection/issues/2492
      *
      * @param string $headerName The name of the header to set
-     * @param array|string|\DateTime $headerValue An array of values or a single value for the specified header field
+     * @param array<mixed>|string|\DateTime $headerValue An array of values or a single value for the specified header field
      * @return void
      */
     public function addHttpHeader(string $headerName, $headerValue): void
@@ -241,7 +241,7 @@ public function addHttpHeader(string $headerName, $headerValue): void
      * Return the specified HTTP header that was previously set.
      *
      * @param string $headerName The name of the header to get the value(s) for
-     * @return array|string|null An array of field values if multiple headers of that name exist, a string value if only one value exists and NULL if there is no such header.
+     * @return array<mixed>|string|null An array of field values if multiple headers of that name exist, a string value if only one value exists and NULL if there is no such header.
      */
     public function getHttpHeader(string $headerName)
     {
@@ -278,6 +278,9 @@ public function getStatusCode(): int
         return $this->statusCode ?? 200;
     }
 
+    /**
+     * @phpstan-assert-if-true non-empty-string $this->contentType
+     */
     public function hasContentType(): bool
     {
         return !empty($this->contentType);
diff --git a/Neos.Flow/Classes/Mvc/Controller/AbstractController.php b/Neos.Flow/Classes/Mvc/Controller/AbstractController.php
index 41cf4e1db7..a7f1b4fdf8 100644
--- a/Neos.Flow/Classes/Mvc/Controller/AbstractController.php
+++ b/Neos.Flow/Classes/Mvc/Controller/AbstractController.php
@@ -57,7 +57,7 @@ abstract class AbstractController implements ControllerInterface
 
     /**
      * The current action request directed to this controller
-     * @var ActionRequest
+     * @var ?ActionRequest
      * @api
      */
     protected $request;
@@ -101,7 +101,7 @@ abstract class AbstractController implements ControllerInterface
     /**
      * A list of IANA media types which are supported by this controller
      *
-     * @var array
+     * @var array<int,string>
      * @see http://www.iana.org/assignments/media-types/index.html
      */
     protected $supportedMediaTypes = ['text/html'];
@@ -121,7 +121,7 @@ abstract class AbstractController implements ControllerInterface
      * @param ActionRequest $request
      * @param ActionResponse $response
      */
-    protected function initializeController(ActionRequest $request, ActionResponse $response)
+    protected function initializeController(ActionRequest $request, ActionResponse $response): void
     {
         // make the current request and response "globally" available to everywhere in this controller.
         $this->request = $request;
@@ -163,18 +163,15 @@ public function getControllerContext()
      * @param string $messageBody text of the FlashMessage
      * @param string $messageTitle optional header of the FlashMessage
      * @param string $severity severity of the FlashMessage (one of the Message::SEVERITY_* constants)
-     * @param array $messageArguments arguments to be passed to the FlashMessage
+     * @param array<mixed> $messageArguments arguments to be passed to the FlashMessage
      * @param integer $messageCode
      * @return void
      * @throws \InvalidArgumentException if the message body is no string
      * @see Error\Message
      * @api
      */
-    public function addFlashMessage($messageBody, $messageTitle = '', $severity = Error\Message::SEVERITY_OK, array $messageArguments = [], $messageCode = null)
+    public function addFlashMessage(string $messageBody, $messageTitle = '', $severity = Error\Message::SEVERITY_OK, array $messageArguments = [], $messageCode = null)
     {
-        if (!is_string($messageBody)) {
-            throw new \InvalidArgumentException('The message body must be of type string, "' . gettype($messageBody) . '" given.', 1243258395);
-        }
         switch ($severity) {
             case Error\Message::SEVERITY_NOTICE:
                 $message = new Error\Notice($messageBody, $messageCode, $messageArguments, $messageTitle);
@@ -213,6 +210,9 @@ public function addFlashMessage($messageBody, $messageTitle = '', $severity = Er
      */
     protected function forward(string $actionName, ?string $controllerName = null, ?string $packageKey = null, array $arguments = []): never
     {
+        if (!$this->request) {
+            throw new \Exception('Cannot resolve request', 1744328653);
+        }
         $nextRequest = clone $this->request;
         $nextRequest->setControllerActionName($actionName);
 
@@ -290,7 +290,7 @@ protected function redirect(string $actionName, ?string $controllerName = null,
         }
         $this->uriBuilder->reset();
         if ($format === null) {
-            $this->uriBuilder->setFormat($this->request->getFormat());
+            $this->uriBuilder->setFormat($this->request?->getFormat());
         } else {
             $this->uriBuilder->setFormat($format);
         }
diff --git a/Neos.Flow/Classes/Mvc/Controller/ActionController.php b/Neos.Flow/Classes/Mvc/Controller/ActionController.php
index 1c933828b4..7ce9ca38f2 100644
--- a/Neos.Flow/Classes/Mvc/Controller/ActionController.php
+++ b/Neos.Flow/Classes/Mvc/Controller/ActionController.php
@@ -37,6 +37,7 @@
 use Neos\Flow\Reflection\ReflectionService;
 use Neos\Utility\TypeHandling;
 use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\StreamInterface;
 use Psr\Log\LoggerInterface;
 
 /**
@@ -110,7 +111,7 @@ class ActionController extends AbstractController
      *
      * array('html' => 'MyCompany\MyApp\MyHtmlView', 'json' => 'MyCompany\...
      *
-     * @var array
+     * @var array<string,array<string>>
      */
     protected $viewFormatToObjectNameMap = [];
 
@@ -145,7 +146,7 @@ class ActionController extends AbstractController
     protected $errorMethodName = 'errorAction';
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $settings;
 
@@ -168,7 +169,7 @@ class ActionController extends AbstractController
     protected $enableDynamicTypeValidation = false;
 
     /**
-     * @param array $settings
+     * @param array<mixed> $settings
      * @return void
      */
     public function injectSettings(array $settings)
@@ -228,8 +229,9 @@ public function processRequest(ActionRequest $request): ResponseInterface
 
         $this->initializeAction();
         $actionInitializationMethodName = 'initialize' . ucfirst($this->actionMethodName);
-        if (method_exists($this, $actionInitializationMethodName)) {
-            call_user_func([$this, $actionInitializationMethodName]);
+        $userFunc = [$this, $actionInitializationMethodName];
+        if (is_callable($userFunc)) {
+            call_user_func($userFunc);
         }
 
         $this->mvcPropertyMappingConfigurationService->initializePropertyMappingConfigurationFromRequest($request, $this->arguments);
@@ -330,7 +332,7 @@ protected function initializeActionMethodArguments(Arguments $arguments)
      * Returns a map of action method names and their parameters.
      *
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of method parameters by action name
+     * @return array<string,mixed> Array of method parameters by action name
      * @Flow\CompileStatic
      */
     public static function getActionMethodParameters($objectManager)
@@ -364,7 +366,7 @@ public static function getActionMethodParameters($objectManager)
      * This is a helper method purely used to make initializeActionMethodValidators()
      * testable without mocking static methods.
      *
-     * @return array
+     * @return array<mixed>
      */
     protected function getInformationNeededForInitializeActionMethodValidators()
     {
@@ -436,7 +438,7 @@ protected function initializeActionMethodValidators(Arguments $arguments)
      * Returns a map of action method names and their validation groups.
      *
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of validation groups by action method name
+     * @return array<string,array<string>> Array of validation groups by action method name
      * @Flow\CompileStatic
      */
     public static function getActionValidationGroups($objectManager)
@@ -463,7 +465,7 @@ public static function getActionValidationGroups($objectManager)
      * Returns a map of action method names and their validation parameters.
      *
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of validate annotation parameters by action method name
+     * @return array<string,array<array{type: ?string, options: array<mixed>, argumentName: string}>> Array of validate annotation parameters by action method name
      * @Flow\CompileStatic
      */
     public static function getActionValidateAnnotationData($objectManager)
@@ -562,6 +564,7 @@ protected function callActionMethod(ActionRequest $request, Arguments $arguments
             return $actionResult;
         }
 
+        /** @phpstan-ignore instanceof.alwaysTrue (fixme: weird initial null state) */
         if ($actionResult === null && $this->view instanceof ViewInterface) {
             $result = $this->view->render();
 
@@ -571,6 +574,10 @@ protected function callActionMethod(ActionRequest $request, Arguments $arguments
                 return $result;
             }
 
+            if (!$result instanceof StreamInterface) {
+                throw new \Exception('Cannot assign object of type ' . get_class($result) . ' to HTTP response body', 1744326907);
+            }
+
             return $httpResponse->withBody($result);
         }
 
@@ -579,7 +586,7 @@ protected function callActionMethod(ActionRequest $request, Arguments $arguments
 
     /**
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of argument names as key by action method name
+     * @return array<string,array<string,array{evaluate: bool}>> Array of argument names as key by action method name
      * @Flow\CompileStatic
      */
     public static function getActionIgnoredValidationArguments($objectManager)
@@ -610,7 +617,7 @@ public static function getActionIgnoredValidationArguments($objectManager)
 
     /**
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of all public action method names, indexed by method name
+     * @return array<string,true> Array of all public action method names, indexed by method name
      * @Flow\CompileStatic
      */
     public static function getPublicActionMethods($objectManager)
@@ -678,7 +685,7 @@ protected function resolveView(ActionRequest $request)
      * @param ViewInterface $view
      * @Flow\Signal
      */
-    protected function emitViewResolved(ViewInterface $view)
+    protected function emitViewResolved(ViewInterface $view): void
     {
     }
 
@@ -755,10 +762,11 @@ protected function errorAction()
      */
     protected function handleTargetNotFoundError()
     {
-        foreach (array_keys($this->request->getArguments()) as $argumentName) {
-            /** @var TargetNotFoundError $targetNotFoundError */
-            $targetNotFoundError = $this->arguments->getValidationResults()->forProperty($argumentName)->getFirstError(TargetNotFoundError::class);
-            if ($targetNotFoundError !== false) {
+        foreach (array_keys($this->request?->getArguments() ?: []) as $argumentName) {
+            $targetNotFoundError = $this->arguments->getValidationResults()
+                ->forProperty($argumentName)
+                ->getFirstError(TargetNotFoundError::class);
+            if ($targetNotFoundError instanceof TargetNotFoundError) {
                 throw new TargetNotFoundException($targetNotFoundError->getMessage(), $targetNotFoundError->getCode());
             }
         }
@@ -788,7 +796,7 @@ protected function addErrorFlashMessage()
      */
     protected function forwardToReferringRequest()
     {
-        $referringRequest = $this->request->getReferringRequest();
+        $referringRequest = $this->request?->getReferringRequest();
         if ($referringRequest === null) {
             return;
         }
@@ -798,7 +806,7 @@ protected function forwardToReferringRequest()
             $packageKey .= '\\' . $subpackageKey;
         }
         $argumentsForNextController = $referringRequest->getArguments();
-        $argumentsForNextController['__submittedArguments'] = $this->request->getArguments();
+        $argumentsForNextController['__submittedArguments'] = $this->request?->getArguments() ?: [];
         $argumentsForNextController['__submittedArgumentValidationResults'] = $this->arguments->getValidationResults();
 
         $this->forward($referringRequest->getControllerActionName(), $referringRequest->getControllerName(), $packageKey, $argumentsForNextController);
diff --git a/Neos.Flow/Classes/Mvc/Controller/Argument.php b/Neos.Flow/Classes/Mvc/Controller/Argument.php
index c125a2f564..dfdce6a42c 100644
--- a/Neos.Flow/Classes/Mvc/Controller/Argument.php
+++ b/Neos.Flow/Classes/Mvc/Controller/Argument.php
@@ -182,7 +182,7 @@ public function setValidator(ValidatorInterface $validator): Argument
     {
         $this->validator = $validator;
         // the validation should not be called on null values - for the cases where the value is required, the error will be thrown in Controller::mapRequestArgumentsToControllerArguments()
-        if ($validator !== null && $this->value !== null) {
+        if ($this->value !== null) {
             $this->validationResults = $this->propertyMapper->getMessages() ?? new Result();
             $validationMessages = $validator->validate($this->value);
             $this->validationResults->merge($validationMessages);
@@ -227,7 +227,7 @@ public function setValue($rawValue): Argument
             $this->dataType = $rawValue['__type'];
         }
         $this->value = $this->propertyMapper->convert($rawValue, $this->dataType, $this->getPropertyMappingConfiguration());
-        $this->validationResults = $this->propertyMapper->getMessages() ?? new Result();
+        $this->validationResults = $this->propertyMapper->getMessages();
         if ($this->validator !== null) {
             $validationMessages = $this->validator->validate($this->value);
             $this->validationResults->merge($validationMessages);
diff --git a/Neos.Flow/Classes/Mvc/Controller/Arguments.php b/Neos.Flow/Classes/Mvc/Controller/Arguments.php
index bae2153ffe..3e4a5d6c2c 100644
--- a/Neos.Flow/Classes/Mvc/Controller/Arguments.php
+++ b/Neos.Flow/Classes/Mvc/Controller/Arguments.php
@@ -24,7 +24,7 @@ class Arguments extends \ArrayObject
 {
     /**
      * Names of the arguments contained by this object
-     * @var array
+     * @var array<mixed>
      */
     protected array $argumentNames = [];
 
@@ -75,6 +75,9 @@ public function append($value): void
     public function offsetUnset($offset): void
     {
         $translatedOffset = $this->validateArgumentExistence($offset);
+        if ($translatedOffset === false) {
+            throw new \Exception('Missing argument', 1744326231);
+        }
         parent::offsetUnset($translatedOffset);
 
         unset($this->argumentNames[$translatedOffset]);
@@ -90,6 +93,9 @@ public function offsetUnset($offset): void
     public function offsetExists($offset): bool
     {
         $translatedOffset = $this->validateArgumentExistence($offset);
+        if ($translatedOffset === false) {
+            throw new \Exception('Missing argument', 1744326202);
+        }
         return parent::offsetExists($translatedOffset);
     }
 
@@ -97,7 +103,7 @@ public function offsetExists($offset): bool
      * Returns the value at the specified index
      *
      * @param mixed $offset Offset
-     * @return Argument The requested argument object
+     * @return ?Argument The requested argument object
      * @throws NoSuchArgumentException if the argument does not exist
      * @api
      */
@@ -154,7 +160,7 @@ public function addArgument(Argument $argument)
      * Returns an argument specified by name
      *
      * @param string $argumentName Name of the argument to retrieve
-     * @return Argument
+     * @return ?Argument
      * @throws NoSuchArgumentException
      * @api
      */
@@ -179,7 +185,7 @@ public function hasArgument($argumentName)
     /**
      * Returns the names of all arguments contained in this object
      *
-     * @return array Argument names
+     * @return array<mixed> Argument names
      * @api
      */
     public function getArgumentNames()
@@ -192,7 +198,7 @@ public function getArgumentNames()
      * value can be set by just calling the setArgumentName() method.
      *
      * @param string $methodName Name of the method
-     * @param array $arguments Method arguments
+     * @param array<mixed> $arguments Method arguments
      * @return void
      * @throws \LogicException
      */
@@ -202,14 +208,20 @@ public function __call($methodName, array $arguments)
             throw new \LogicException('Unknown method "' . $methodName . '".', 1210858451);
         }
         $firstLowerCaseArgumentName = $this->validateArgumentExistence(strtolower($methodName[3]) . substr($methodName, 4));
+        if ($firstLowerCaseArgumentName === false) {
+            throw new \Exception('Missing argument', 1744326132);
+        }
         $firstUpperCaseArgumentName = $this->validateArgumentExistence(ucfirst(substr($methodName, 3)));
+        if ($firstUpperCaseArgumentName === false) {
+            throw new \Exception('Missing argument', 1744326142);
+        }
 
         if (in_array($firstLowerCaseArgumentName, $this->getArgumentNames())) {
             $argument = parent::offsetGet($firstLowerCaseArgumentName);
-            $argument->setValue($arguments[0]);
+            $argument?->setValue($arguments[0]);
         } elseif (in_array($firstUpperCaseArgumentName, $this->getArgumentNames())) {
             $argument = parent::offsetGet($firstUpperCaseArgumentName);
-            $argument->setValue($arguments[0]);
+            $argument?->setValue($arguments[0]);
         }
     }
 
diff --git a/Neos.Flow/Classes/Mvc/Controller/MvcPropertyMappingConfigurationService.php b/Neos.Flow/Classes/Mvc/Controller/MvcPropertyMappingConfigurationService.php
index 2ad52daefe..c9ede36b8d 100644
--- a/Neos.Flow/Classes/Mvc/Controller/MvcPropertyMappingConfigurationService.php
+++ b/Neos.Flow/Classes/Mvc/Controller/MvcPropertyMappingConfigurationService.php
@@ -48,7 +48,7 @@ class MvcPropertyMappingConfigurationService
     /**
      * Generate a request hash for a list of form fields
      *
-     * @param array $formFieldNames Array of form fields
+     * @param array<mixed> $formFieldNames Array of form fields
      * @param string $fieldNamePrefix
      * @return string trusted properties token
      * @throws InvalidArgumentForHashGenerationException
@@ -69,6 +69,7 @@ public function generateTrustedPropertiesToken($formFieldNames, $fieldNamePrefix
                 }
 
                 if ($i === count($formFieldParts) - 1) {
+                    /** @phpstan-ignore booleanAnd.rightAlwaysFalse (not sure, though) */
                     if (isset($currentPosition[$formFieldPart]) && is_array($currentPosition[$formFieldPart])) {
                         throw new InvalidArgumentForHashGenerationException('The form field "' . $formField . '" is declared as string, but it collides with a previous form field of the same name which declared the field as array. This is an inconsistency you need to fix inside your generated form. (Array overridden by String)', 1255072587);
                     }
@@ -90,6 +91,7 @@ public function generateTrustedPropertiesToken($formFieldNames, $fieldNamePrefix
             }
         }
         if ($fieldNamePrefix !== '') {
+            /** @phpstan-ignore nullCoalesce.offset (set by reference) */
             $formFieldArray = $formFieldArray[$fieldNamePrefix] ?? [];
         }
         return $this->serializeAndHashFormFieldArray($formFieldArray);
@@ -98,7 +100,7 @@ public function generateTrustedPropertiesToken($formFieldNames, $fieldNamePrefix
     /**
      * Serialize and hash the form field array
      *
-     * @param array $formFieldArray form field array to be serialized and hashed
+     * @param array<mixed> $formFieldArray form field array to be serialized and hashed
      * @return string Hash
      */
     protected function serializeAndHashFormFieldArray($formFieldArray)
@@ -128,10 +130,11 @@ public function initializePropertyMappingConfigurationFromRequest(ActionRequest
 
         $trustedProperties = unserialize($serializedTrustedProperties);
         foreach ($trustedProperties as $propertyName => $propertyConfiguration) {
-            if (!$controllerArguments->hasArgument($propertyName)) {
+            $argument = $controllerArguments->getArgument($propertyName);
+            if (!$argument) {
                 continue;
             }
-            $propertyMappingConfiguration = $controllerArguments->getArgument($propertyName)->getPropertyMappingConfiguration();
+            $propertyMappingConfiguration = $argument->getPropertyMappingConfiguration();
             $this->modifyPropertyMappingConfiguration($propertyConfiguration, $propertyMappingConfiguration);
         }
     }
@@ -143,7 +146,7 @@ public function initializePropertyMappingConfigurationFromRequest(ActionRequest
      *
      * All other properties are specified as allowed properties.
      *
-     * @param array $propertyConfiguration
+     * @param mixed $propertyConfiguration
      * @param PropertyMappingConfiguration $propertyMappingConfiguration
      * @return void
      */
diff --git a/Neos.Flow/Classes/Mvc/Controller/RestController.php b/Neos.Flow/Classes/Mvc/Controller/RestController.php
index 849c637e94..122fd5cc1e 100644
--- a/Neos.Flow/Classes/Mvc/Controller/RestController.php
+++ b/Neos.Flow/Classes/Mvc/Controller/RestController.php
@@ -99,7 +99,10 @@ protected function resolveActionMethodName(ActionRequest $request): string
      */
     protected function initializeCreateAction()
     {
-        $propertyMappingConfiguration = $this->arguments[$this->resourceArgumentName]->getPropertyMappingConfiguration();
+        $propertyMappingConfiguration = $this->arguments[$this->resourceArgumentName]?->getPropertyMappingConfiguration();
+        if (!$propertyMappingConfiguration) {
+            throw new \Exception('Missing property mapping configuration for ' . $this->resourceArgumentName, 1744328226);
+        }
         $propertyMappingConfiguration->setTypeConverterOption(PersistentObjectConverter::class, PersistentObjectConverter::CONFIGURATION_CREATION_ALLOWED, true);
         $propertyMappingConfiguration->allowAllProperties();
     }
@@ -111,7 +114,10 @@ protected function initializeCreateAction()
      */
     protected function initializeUpdateAction()
     {
-        $propertyMappingConfiguration = $this->arguments[$this->resourceArgumentName]->getPropertyMappingConfiguration();
+        $propertyMappingConfiguration = $this->arguments[$this->resourceArgumentName]?->getPropertyMappingConfiguration();
+        if (!$propertyMappingConfiguration) {
+            throw new \Exception('Missing property mapping configuration for ' . $this->resourceArgumentName, 1744328226);
+        }
         $propertyMappingConfiguration->setTypeConverterOption(PersistentObjectConverter::class, PersistentObjectConverter::CONFIGURATION_MODIFICATION_ALLOWED, true);
         $propertyMappingConfiguration->allowAllProperties();
     }
diff --git a/Neos.Flow/Classes/Mvc/Dispatcher.php b/Neos.Flow/Classes/Mvc/Dispatcher.php
index 8d47161edf..715884cdca 100644
--- a/Neos.Flow/Classes/Mvc/Dispatcher.php
+++ b/Neos.Flow/Classes/Mvc/Dispatcher.php
@@ -68,7 +68,7 @@ public function injectObjectManager(ObjectManagerInterface $objectManager)
     /**
      * @param Context $context
      */
-    public function injectSecurityContext(Context $context)
+    public function injectSecurityContext(Context $context): void
     {
         $this->securityContext = $context;
     }
@@ -76,7 +76,7 @@ public function injectSecurityContext(Context $context)
     /**
      * @param FirewallInterface $firewall
      */
-    public function injectFirewall(FirewallInterface $firewall)
+    public function injectFirewall(FirewallInterface $firewall): void
     {
         $this->firewall = $firewall;
     }
@@ -193,7 +193,7 @@ protected function resolveController(ActionRequest $request): ControllerInterfac
 
         $controller = $this->objectManager->get($controllerObjectName);
         if (!$controller instanceof ControllerInterface) {
-            throw new Controller\Exception\InvalidControllerException('Invalid controller "' . $request->getControllerObjectName() . '". The controller must be a valid request handling controller, ' . (is_object($controller) ? get_class($controller) : gettype($controller)) . ' given.', 1202921619, null, $request);
+            throw new Controller\Exception\InvalidControllerException('Invalid controller "' . $request->getControllerObjectName() . '". The controller must be a valid request handling controller, ' . get_class($controller) . ' given.', 1202921619, null, $request);
         }
         return $controller;
     }
diff --git a/Neos.Flow/Classes/Mvc/FlashMessage/FlashMessageContainer.php b/Neos.Flow/Classes/Mvc/FlashMessage/FlashMessageContainer.php
index c8f274eedd..12ecadc80e 100644
--- a/Neos.Flow/Classes/Mvc/FlashMessage/FlashMessageContainer.php
+++ b/Neos.Flow/Classes/Mvc/FlashMessage/FlashMessageContainer.php
@@ -22,7 +22,7 @@
 class FlashMessageContainer
 {
     /**
-     * @var array
+     * @var array<int,Message>
      */
     protected $messages = [];
 
diff --git a/Neos.Flow/Classes/Mvc/FlashMessage/FlashMessageService.php b/Neos.Flow/Classes/Mvc/FlashMessage/FlashMessageService.php
index 48dad0da21..f7f0bb02e0 100644
--- a/Neos.Flow/Classes/Mvc/FlashMessage/FlashMessageService.php
+++ b/Neos.Flow/Classes/Mvc/FlashMessage/FlashMessageService.php
@@ -41,7 +41,7 @@ class FlashMessageService
 
     /**
      * @Flow\InjectConfiguration(path="mvc.flashMessages.containers")
-     * @var array
+     * @var array<mixed>
      */
     protected $flashMessageContainerConfiguration;
 
diff --git a/Neos.Flow/Classes/Mvc/FlashMessage/Storage/FlashMessageCookieStorage.php b/Neos.Flow/Classes/Mvc/FlashMessage/Storage/FlashMessageCookieStorage.php
index ee1da13493..b5b4f292f0 100644
--- a/Neos.Flow/Classes/Mvc/FlashMessage/Storage/FlashMessageCookieStorage.php
+++ b/Neos.Flow/Classes/Mvc/FlashMessage/Storage/FlashMessageCookieStorage.php
@@ -26,7 +26,7 @@ class FlashMessageCookieStorage implements FlashMessageStorageInterface
     const DEFAULT_COOKIE_NAME = 'Neos_Flow_FlashMessages';
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     private $options;
 
@@ -41,7 +41,7 @@ class FlashMessageCookieStorage implements FlashMessageStorageInterface
     private $flashMessageContainer;
 
     /**
-     * @param array $options
+     * @param array<mixed> $options
      */
     public function __construct(array $options = [])
     {
@@ -100,13 +100,13 @@ public function persist(HttpResponseInterface $response): HttpResponseInterface
         foreach ($this->flashMessageContainer->getMessagesAndFlush() as $flashMessage) {
             $serializedMessages[] = $this->serializeMessage($flashMessage);
         }
-        $cookie = new Cookie($this->cookieName, json_encode($serializedMessages), 0, null, null, '/', false, false);
+        $cookie = new Cookie($this->cookieName, json_encode($serializedMessages, JSON_THROW_ON_ERROR), 0, null, null, '/', false, false);
         return $response->withAddedHeader('Set-Cookie', (string)$cookie);
     }
 
     /**
      * @param Message $message
-     * @return array
+     * @return array<string,mixed>
      */
     private function serializeMessage(Message $message): array
     {
@@ -121,7 +121,7 @@ private function serializeMessage(Message $message): array
     }
 
     /**
-     * @param array $messageArray
+     * @param array<mixed> $messageArray
      * @return Message
      */
     private function deserializeMessage(array $messageArray): Message
diff --git a/Neos.Flow/Classes/Mvc/FlashMessage/Storage/FlashMessageSessionStorage.php b/Neos.Flow/Classes/Mvc/FlashMessage/Storage/FlashMessageSessionStorage.php
index e0ecc97a02..44cbf721da 100644
--- a/Neos.Flow/Classes/Mvc/FlashMessage/Storage/FlashMessageSessionStorage.php
+++ b/Neos.Flow/Classes/Mvc/FlashMessage/Storage/FlashMessageSessionStorage.php
@@ -29,7 +29,7 @@ class FlashMessageSessionStorage implements FlashMessageStorageInterface
     protected $session;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     private $options;
 
@@ -44,7 +44,7 @@ class FlashMessageSessionStorage implements FlashMessageStorageInterface
     private $flashMessageContainer;
 
     /**
-     * @param array $options
+     * @param array<mixed> $options
      */
     public function __construct(array $options = [])
     {
diff --git a/Neos.Flow/Classes/Mvc/RequestMatcher.php b/Neos.Flow/Classes/Mvc/RequestMatcher.php
index a82b8e5050..4ca759c9bd 100644
--- a/Neos.Flow/Classes/Mvc/RequestMatcher.php
+++ b/Neos.Flow/Classes/Mvc/RequestMatcher.php
@@ -30,7 +30,7 @@ class RequestMatcher
      * return false. This case is primarily needed
      * if no parentRequest exists.
      *
-     * @var ActionRequest
+     * @var ?ActionRequest
      */
     protected $request;
 
@@ -41,7 +41,7 @@ class RequestMatcher
      * and mainRequest Matchers through the addWeight
      * method
      *
-     * @var RequestMatcher
+     * @var ?RequestMatcher
      */
     protected $parentMatcher;
 
@@ -163,7 +163,7 @@ public function getParentRequest()
             return new RequestMatcher();
         }
         $this->addWeight(1000000);
-        return new RequestMatcher($this->request->getParentRequest(), $this);
+        return new RequestMatcher($this->request?->getParentRequest(), $this);
     }
 
     /**
@@ -175,7 +175,7 @@ public function getParentRequest()
     public function getMainRequest()
     {
         $this->addWeight(100000);
-        return new RequestMatcher($this->request->getMainRequest(), $this);
+        return new RequestMatcher($this->request?->getMainRequest(), $this);
     }
 
     /**
diff --git a/Neos.Flow/Classes/Mvc/Routing/AbstractRoutePart.php b/Neos.Flow/Classes/Mvc/Routing/AbstractRoutePart.php
index 18e7b8c60f..9b49add5ff 100644
--- a/Neos.Flow/Classes/Mvc/Routing/AbstractRoutePart.php
+++ b/Neos.Flow/Classes/Mvc/Routing/AbstractRoutePart.php
@@ -20,7 +20,7 @@ abstract class AbstractRoutePart implements RoutePartInterface
     /**
      * Name of the Route Part
      *
-     * @var string
+     * @var ?string
      */
     protected $name = null;
 
@@ -55,7 +55,7 @@ abstract class AbstractRoutePart implements RoutePartInterface
     /**
      * Contains options for this Route Part.
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $options = [];
 
@@ -73,7 +73,7 @@ public function setName($partName)
     /**
      * Returns name of the Route Part.
      *
-     * @return string
+     * @return ?string
      */
     public function getName()
     {
@@ -180,7 +180,7 @@ public function isLowerCase()
      * Defines options for this Route Part.
      * Options can be used to enrich a route part with parameters or settings like case sensivity.
      *
-     * @param array $options
+     * @param array<mixed> $options
      * @return void
      */
     public function setOptions(array $options)
@@ -189,7 +189,7 @@ public function setOptions(array $options)
     }
 
     /**
-     * @return array options of this Route Part.
+     * @return array<mixed> options of this Route Part.
      */
     public function getOptions()
     {
diff --git a/Neos.Flow/Classes/Mvc/Routing/AttributeRoutesProvider.php b/Neos.Flow/Classes/Mvc/Routing/AttributeRoutesProvider.php
index 039215da9c..b62128a9ee 100644
--- a/Neos.Flow/Classes/Mvc/Routing/AttributeRoutesProvider.php
+++ b/Neos.Flow/Classes/Mvc/Routing/AttributeRoutesProvider.php
@@ -92,13 +92,25 @@ public function getRoutes(): Routes
             $routes = [...$routes, ...$routesForClass];
         }
 
-        $routes = array_map(static fn (array $routeConfiguration): Route => Route::fromConfiguration($routeConfiguration), $routes);
+        $routes = array_map(
+            static fn (array $routeConfiguration): Route => Route::fromConfiguration($routeConfiguration),
+            $routes
+        );
         return Routes::create(...$routes);
     }
 
     /**
      * @param ObjectManagerInterface $objectManager
-     * @return array<string, array<int, mixed>>
+     * @return array<string,array<int,array{
+     *      name?: string,
+     *      uriPattern: string,
+     *      defaults?: array<mixed>,
+     *      routeParts?: array<mixed>,
+     *      toLowerCase?: bool,
+     *      appendExceedingArguments?: bool,
+     *      cache?: array{lifetime?: int, tags?: array<mixed>},
+     *      httpMethods?: list<string>
+     * }>>
      * @throws InvalidActionNameException
      * @throws InvalidControllerException
      * @throws \Neos\Flow\Utility\Exception
@@ -119,7 +131,10 @@ public static function compileRoutesConfiguration(ObjectManagerInterface $object
             }
 
             $controllerObjectName = $objectManager->getCaseSensitiveObjectName($className);
-            $controllerPackageKey = $objectManager->getPackageKeyByObjectName($controllerObjectName);
+            $controllerPackageKey = $controllerObjectName ? $objectManager->getPackageKeyByObjectName($controllerObjectName) : null;
+            if (!$controllerPackageKey) {
+                throw new \Exception('Could not resolve package key for class ' . $className);
+            }
             $controllerPackageNamespace = str_replace('.', '\\', $controllerPackageKey);
             if (!str_ends_with($className, 'Controller')) {
                 throw new InvalidControllerException('Only for controller classes');
@@ -144,26 +159,24 @@ public static function compileRoutesConfiguration(ObjectManagerInterface $object
                 }
                 $annotations = $reflectionService->getMethodAnnotations($className, $methodName, Flow\Route::class);
                 foreach ($annotations as $annotation) {
-                    if ($annotation instanceof Flow\Route) {
-                        $controller = substr($controllerName, 0, -10);
-                        $action = substr($methodName, 0, -6);
-                        $configuration = [
-                            'name' => $controllerPackageKey . ' :: ' . $controller . ' :: ' . ($annotation->name ?: $action),
-                            'uriPattern' => $annotation->uriPattern,
-                            'httpMethods' => $annotation->httpMethods,
-                            'defaults' => Arrays::arrayMergeRecursiveOverrule(
-                                [
-                                    '@package' => $controllerPackageKey,
-                                    '@subpackage' => $subPackage,
-                                    '@controller' => $controller,
-                                    '@action' => $action,
-                                    '@format' => 'html'
-                                ],
-                                $annotation->defaults ?? []
-                            )
-                        ];
-                        $routesByClassName[$className][] = $configuration;
-                    }
+                    $controller = substr($controllerName, 0, -10);
+                    $action = substr($methodName, 0, -6);
+                    $configuration = [
+                        'name' => $controllerPackageKey . ' :: ' . $controller . ' :: ' . ($annotation->name ?: $action),
+                        'uriPattern' => $annotation->uriPattern,
+                        'httpMethods' => $annotation->httpMethods,
+                        'defaults' => Arrays::arrayMergeRecursiveOverrule(
+                            [
+                                '@package' => $controllerPackageKey,
+                                '@subpackage' => $subPackage,
+                                '@controller' => $controller,
+                                '@action' => $action,
+                                '@format' => 'html'
+                            ],
+                            $annotation->defaults ?? []
+                        )
+                    ];
+                    $routesByClassName[$className][] = $configuration;
                 }
             }
         }
diff --git a/Neos.Flow/Classes/Mvc/Routing/Dto/ResolveContext.php b/Neos.Flow/Classes/Mvc/Routing/Dto/ResolveContext.php
index 64e8d11318..d488159562 100644
--- a/Neos.Flow/Classes/Mvc/Routing/Dto/ResolveContext.php
+++ b/Neos.Flow/Classes/Mvc/Routing/Dto/ResolveContext.php
@@ -31,7 +31,7 @@ final class ResolveContext
     /**
      * Route values to build the URI, for example ['@action' => 'index', 'someArgument' => 'foo', ...]
      *
-     * @var array
+     * @var array<mixed>
      */
     private $routeValues;
 
@@ -56,7 +56,7 @@ final class ResolveContext
 
     /**
      * @param UriInterface $baseUri The base URI, retrieved from the current request URI or from configuration, if specified. Required to fill in parts of the result when resolving absolute URIs
-     * @param array $routeValues Route values to build the URI, for example ['@action' => 'index', 'someArgument' => 'foo', ...]
+     * @param array<mixed> $routeValues Route values to build the URI, for example ['@action' => 'index', 'someArgument' => 'foo', ...]
      * @param bool $forceAbsoluteUri Whether or not an absolute URI is to be returned
      * @param string $uriPathPrefix A prefix to be prepended to any resolved URI. Not allowed to start with "/".
      * @param RouteParameters $parameters
@@ -83,7 +83,7 @@ public function getBaseUri(): UriInterface
     }
 
     /**
-     * @return array
+     * @return array<mixed>
      */
     public function getRouteValues(): array
     {
diff --git a/Neos.Flow/Classes/Mvc/Routing/Dto/RouteParameters.php b/Neos.Flow/Classes/Mvc/Routing/Dto/RouteParameters.php
index aa1dab51f2..b17eac637f 100644
--- a/Neos.Flow/Classes/Mvc/Routing/Dto/RouteParameters.php
+++ b/Neos.Flow/Classes/Mvc/Routing/Dto/RouteParameters.php
@@ -29,12 +29,12 @@ final class RouteParameters implements CacheAwareInterface
     /**
      * The parameters as simple key/value pair in the format ['<parameter1Key>' => <parameter1Value>, ...]
      *
-     * @var array
+     * @var array<string, mixed>
      */
     private $parameters;
 
     /**
-     * @param array $parameters simple key/value pair in the format ['<parameter1Key>' => <parameter1Value>, ...]
+     * @param array<string, mixed> $parameters simple key/value pair in the format ['<parameter1Key>' => <parameter1Value>, ...]
      */
     private function __construct(array $parameters)
     {
@@ -61,7 +61,7 @@ public static function createEmpty(): self
     public function withParameter(string $parameterName, $parameterValue): self
     {
         if (!TypeHandling::isLiteral(gettype($parameterValue)) && (!$parameterValue instanceof CacheAwareInterface)) {
-            throw new \InvalidArgumentException(sprintf('Parameter values must be literal types or implement the CacheAwareInterface, given: "%s"', is_object($parameterValue) ? get_class($parameterValue) : gettype($parameterValue)), 1511194273);
+            throw new \InvalidArgumentException(sprintf('Parameter values must be literal types or implement the CacheAwareInterface, given: "%s"', gettype($parameterValue)), 1511194273);
         }
         $newParameters = $this->parameters;
         $newParameters[$parameterName] = $parameterValue;
@@ -99,7 +99,7 @@ public function isEmpty(): bool
     }
 
     /**
-     * @return array
+     * @return array<string, mixed>
      */
     public function toArray(): array
     {
diff --git a/Neos.Flow/Classes/Mvc/Routing/Dto/RouteTags.php b/Neos.Flow/Classes/Mvc/Routing/Dto/RouteTags.php
index 44a1833079..865ca12583 100644
--- a/Neos.Flow/Classes/Mvc/Routing/Dto/RouteTags.php
+++ b/Neos.Flow/Classes/Mvc/Routing/Dto/RouteTags.php
@@ -29,7 +29,7 @@ final class RouteTags
     const PATTERN_TAG = '/^[a-zA-Z0-9_%\-&]{1,250}$/';
 
     /**
-     * @var string[] numeric array of strings satisfying the PATTERN_TAG regex
+     * @var array<int,string> numeric array of strings satisfying the PATTERN_TAG regex
      */
     private $tags = [];
 
@@ -113,11 +113,8 @@ public function withTag(string $tag): self
      * @param string $tag
      * @throws \InvalidArgumentException
      */
-    private static function validateTag($tag)
+    private static function validateTag(string $tag): void
     {
-        if (!is_string($tag)) {
-            throw new \InvalidArgumentException(sprintf('RouteTags have to be strings, %s given', is_object($tag) ? get_class($tag) : gettype($tag)), 1512553153);
-        }
         if (preg_match(self::PATTERN_TAG, $tag) !== 1) {
             throw new \InvalidArgumentException(sprintf('The given string "%s" is not a valid tag', $tag), 1511807639);
         }
@@ -137,7 +134,7 @@ public function has(string $tag)
     /**
      * Returns the tags of this tag collection as value array
      *
-     * @return array
+     * @return array<int,string>
      */
     public function getTags(): array
     {
diff --git a/Neos.Flow/Classes/Mvc/Routing/Dto/UriConstraints.php b/Neos.Flow/Classes/Mvc/Routing/Dto/UriConstraints.php
index cfead76153..1b2a235e1b 100644
--- a/Neos.Flow/Classes/Mvc/Routing/Dto/UriConstraints.php
+++ b/Neos.Flow/Classes/Mvc/Routing/Dto/UriConstraints.php
@@ -48,12 +48,12 @@ final class UriConstraints
     const HTTP_DEFAULT_HOST = 'localhost';
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     private $constraints;
 
     /**
-     * @param array $constraints array of constraints with one of the CONSTRAINT_* constants as keys and corresponding values
+     * @param array<mixed> $constraints array of constraints with one of the CONSTRAINT_* constants as keys and corresponding values
      */
     private function __construct(array $constraints)
     {
@@ -212,7 +212,7 @@ public function withQueryString(string $queryString): self
     /**
      * Create a new instance with a query string corresponding to the given $values merged with any existing query string constraint
      *
-     * @param array $values
+     * @param array<mixed> $values
      * @return UriConstraints
      */
     public function withAddedQueryValues(array $values): self
diff --git a/Neos.Flow/Classes/Mvc/Routing/DynamicRoutePart.php b/Neos.Flow/Classes/Mvc/Routing/DynamicRoutePart.php
index b7c9e62347..29b1c6a02a 100644
--- a/Neos.Flow/Classes/Mvc/Routing/DynamicRoutePart.php
+++ b/Neos.Flow/Classes/Mvc/Routing/DynamicRoutePart.php
@@ -140,7 +140,7 @@ protected function findValueToMatch($routePath)
      */
     protected function matchValue($value)
     {
-        if ($value === null || $value === '') {
+        if ($value === '') {
             return false;
         }
         return new MatchResult(rawurldecode($value));
@@ -157,7 +157,7 @@ protected function matchValue($value)
      */
     protected function removeMatchingPortionFromRequestPath(&$routePath, $valueToMatch)
     {
-        if ($valueToMatch !== null && $valueToMatch !== '') {
+        if ($valueToMatch !== '') {
             $routePath = substr($routePath, strlen($valueToMatch));
         }
     }
@@ -167,7 +167,7 @@ protected function removeMatchingPortionFromRequestPath(&$routePath, $valueToMat
      * If a corresponding element is found in $routeValues, this element is removed from the array.
      * @see resolveWithParameters()
      *
-     * @param array $routeValues An array with key/value pairs to be resolved by Dynamic Route Parts.
+     * @param array<mixed> $routeValues An array with key/value pairs to be resolved by Dynamic Route Parts.
      * @return bool|ResolveResult true or an instance of ResolveResult if current Route Part could be resolved, otherwise false
      */
     final public function resolve(array &$routeValues)
@@ -179,7 +179,7 @@ final public function resolve(array &$routeValues)
      * Checks whether $routeValues contains elements which correspond to this Dynamic Route Part.
      * If a corresponding element is found in $routeValues, this element is removed from the array.
      *
-     * @param array $routeValues
+     * @param array<mixed> $routeValues
      * @param RouteParameters $parameters
      * @return bool|ResolveResult
      */
@@ -203,8 +203,8 @@ final public function resolveWithParameters(array &$routeValues, RouteParameters
      * Returns the route value of the current route part.
      * This method can be overridden by custom RoutePartHandlers to implement custom resolving mechanisms.
      *
-     * @param array $routeValues An array with key/value pairs to be resolved by Dynamic Route Parts.
-     * @return string|array|null value to resolve.
+     * @param array<mixed> $routeValues An array with key/value pairs to be resolved by Dynamic Route Parts.
+     * @return string|array<mixed>|null value to resolve.
      * @api
      */
     protected function findValueToResolve(array $routeValues)
diff --git a/Neos.Flow/Classes/Mvc/Routing/IdentityRoutePart.php b/Neos.Flow/Classes/Mvc/Routing/IdentityRoutePart.php
index f62a9afa79..45899b32b2 100644
--- a/Neos.Flow/Classes/Mvc/Routing/IdentityRoutePart.php
+++ b/Neos.Flow/Classes/Mvc/Routing/IdentityRoutePart.php
@@ -124,7 +124,7 @@ public function getUriPattern()
      */
     protected function matchValue($value)
     {
-        if ($value === null || $value === '') {
+        if ($value === '') {
             return false;
         }
         $identifier = $this->getObjectIdentifierFromPathSegment($value);
@@ -202,13 +202,10 @@ protected function resolveValue($value)
         } elseif ($value instanceof $this->objectType) {
             $identifier = $this->persistenceManager->getIdentifierByObject($value);
         }
-        if ($identifier === null || (!is_string($identifier) && !is_integer($identifier))) {
+        if (!is_string($identifier)) {
             return false;
         }
         $pathSegment = $this->getPathSegmentByIdentifier($identifier);
-        if ($pathSegment === null) {
-            return false;
-        }
         $this->value = $pathSegment;
         return true;
     }
@@ -277,7 +274,7 @@ protected function createPathSegmentForObject($object)
                         $dateFormat = isset($dynamicPathSegmentParts[1]) ? trim($dynamicPathSegmentParts[1]) : 'Y-m-d';
                         $pathSegment .= $this->rewriteForUri($dynamicPathSegment->format($dateFormat));
                     } else {
-                        throw new InvalidUriPatternException(sprintf('Invalid uriPattern "%s" for route part "%s". Property "%s" must be of type string or \DateTime. "%s" given.', $this->getUriPattern(), $this->getName(), $propertyPath, is_object($dynamicPathSegment) ? get_class($dynamicPathSegment) : gettype($dynamicPathSegment)), 1316442409);
+                        throw new InvalidUriPatternException(sprintf('Invalid uriPattern "%s" for route part "%s". Property "%s" must be of type string or \DateTime. "%s" given.', $this->getUriPattern(), $this->getName(), $propertyPath, get_class($dynamicPathSegment)), 1316442409);
                     }
                 } else {
                     $pathSegment .= $this->rewriteForUri((string)$dynamicPathSegment);
@@ -291,7 +288,7 @@ protected function createPathSegmentForObject($object)
      * Creates a new ObjectPathMapping and stores it in the repository
      *
      * @param string $pathSegment
-     * @param string|integer $identifier
+     * @param string $identifier
      * @return void
      */
     protected function storeObjectPathMapping($pathSegment, $identifier)
@@ -327,12 +324,12 @@ protected function rewriteForUri(string $value)
         $value = strtr($value, $transliteration);
 
         $spaceCharacter = '-';
-        $value = preg_replace('/[ \-+_]+/', $spaceCharacter, $value);
+        $value = preg_replace('/[ \-+_]+/', $spaceCharacter, $value) ?: '';
 
-        $value = preg_replace('/[^-a-z0-9.\\' . $spaceCharacter . ']/i', '', $value);
+        $value = preg_replace('/[^-a-z0-9.\\' . $spaceCharacter . ']/i', '', $value) ?: '';
 
-        $value = preg_replace('/\\' . $spaceCharacter . '{2,}/', $spaceCharacter, $value);
-        $value = trim($value, $spaceCharacter);
+        $value = preg_replace('/\\' . $spaceCharacter . '{2,}/', $spaceCharacter, $value) ?: '';
+        $value = trim($value, $spaceCharacter) ?: '';
 
         return $value;
     }
diff --git a/Neos.Flow/Classes/Mvc/Routing/ObjectPathMappingRepository.php b/Neos.Flow/Classes/Mvc/Routing/ObjectPathMappingRepository.php
index e6eabd2b5a..2468ad8c99 100644
--- a/Neos.Flow/Classes/Mvc/Routing/ObjectPathMappingRepository.php
+++ b/Neos.Flow/Classes/Mvc/Routing/ObjectPathMappingRepository.php
@@ -38,7 +38,7 @@ class ObjectPathMappingRepository extends Repository
     protected $entityManager;
 
     /**
-     * @var array
+     * @var array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING>
      */
     protected $defaultOrderings = [
         'objectType' => QueryInterface::ORDER_ASCENDING,
@@ -55,7 +55,7 @@ class ObjectPathMappingRepository extends Repository
     public function findOneByObjectTypeUriPatternAndPathSegment($objectType, $uriPattern, $pathSegment, $caseSensitive = false)
     {
         $query = $this->createQuery();
-        return $query->matching(
+        $result = $query->matching(
             $query->logicalAnd(
                 $query->equals('objectType', $objectType),
                 $query->equals('uriPattern', $uriPattern),
@@ -64,6 +64,8 @@ public function findOneByObjectTypeUriPatternAndPathSegment($objectType, $uriPat
         )
         ->execute()
         ->getFirst();
+
+        return $result instanceof ObjectPathMapping ? $result : null;
     }
 
     /**
@@ -76,7 +78,7 @@ public function findOneByObjectTypeUriPatternAndPathSegment($objectType, $uriPat
     public function findOneByObjectTypeUriPatternAndIdentifier($objectType, $uriPattern, $identifier)
     {
         $query = $this->createQuery();
-        return $query->matching(
+        $result = $query->matching(
             $query->logicalAnd(
                 $query->equals('objectType', $objectType),
                 $query->equals('uriPattern', $uriPattern),
@@ -85,6 +87,8 @@ public function findOneByObjectTypeUriPatternAndIdentifier($objectType, $uriPatt
         )
         ->execute()
         ->getFirst();
+
+        return $result instanceof ObjectPathMapping ? $result : null;
     }
 
     /**
diff --git a/Neos.Flow/Classes/Mvc/Routing/ParameterAwareRoutePartInterface.php b/Neos.Flow/Classes/Mvc/Routing/ParameterAwareRoutePartInterface.php
index 6414a20e5a..ce2774dc47 100644
--- a/Neos.Flow/Classes/Mvc/Routing/ParameterAwareRoutePartInterface.php
+++ b/Neos.Flow/Classes/Mvc/Routing/ParameterAwareRoutePartInterface.php
@@ -37,7 +37,7 @@ public function matchWithParameters(&$routePath, RouteParameters $parameters);
      * removes resolved elements from $routeValues-Array.
      * This is why $routeValues has to be passed by reference.
      *
-     * @param array &$routeValues An array with key/value pairs to be resolved by Dynamic Route Parts.
+     * @param array<mixed> &$routeValues An array with key/value pairs to be resolved by Dynamic Route Parts.
      * @param RouteParameters $parameters The Routing RouteParameters that can be registered via HTTP middleware
      * @return bool|ResolveResult true or an instance of ResolveResult if Route Part can resolve one or more $routeValues elements, otherwise false.
      */
diff --git a/Neos.Flow/Classes/Mvc/Routing/Route.php b/Neos.Flow/Classes/Mvc/Routing/Route.php
index eb7998a333..6e37b61714 100644
--- a/Neos.Flow/Classes/Mvc/Routing/Route.php
+++ b/Neos.Flow/Classes/Mvc/Routing/Route.php
@@ -48,7 +48,7 @@ class Route
     /**
      * Default values
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $defaults = [];
 
@@ -91,7 +91,7 @@ class Route
      * Contains the routing results (indexed by "package", "controller" and
      * "action") after a successful call of matches()
      *
-     * @var array|null
+     * @var array<mixed>|null
      */
     protected $matchResults = [];
 
@@ -112,7 +112,7 @@ class Route
     /**
      * The merged UriConstraints of all Route Parts after resolving
      *
-     * @var UriConstraints|null
+     * @var ?UriConstraints
      */
     protected $resolvedUriConstraints;
 
@@ -134,7 +134,7 @@ class Route
      * Contains associative array of Route Part options
      * (key: Route Part name, value: array of Route Part options)
      *
-     * @var array
+     * @var array<string,array<mixed>>
      */
     protected $routePartsConfiguration = [];
 
@@ -172,9 +172,22 @@ class Route
      */
     protected $routeValuesNormalizer;
 
+    /**
+     * @param array{
+     *     name?: string,
+     *     uriPattern: string,
+     *     defaults?: array<mixed>,
+     *     routeParts?: array<mixed>,
+     *     toLowerCase?: bool,
+     *     appendExceedingArguments?: bool,
+     *     cache?: array{lifetime?: int, tags?: array<mixed>},
+     *     httpMethods?: list<string>
+     * } $configuration
+     * @return static
+     */
     public static function fromConfiguration(array $configuration): static
     {
-        /** @phpstan-ignore-next-line phpstan doesn't respekt the consistent constructor flag in the class doc block */
+        /** @phpstan-ignore new.static */
         $route = new static();
         if (isset($configuration['name'])) {
             $route->setName($configuration['name']);
@@ -232,7 +245,7 @@ public function getName()
      * Sets default values for this Route.
      * This array is merged with the actual matchResults when match() is called.
      *
-     * @param array $defaults
+     * @param array<mixed> $defaults
      * @return void
      */
     public function setDefaults(array $defaults)
@@ -243,7 +256,7 @@ public function setDefaults(array $defaults)
     /**
      * Returns default values for this Route.
      *
-     * @return array Route defaults
+     * @return array<mixed> Route defaults
      */
     public function getDefaults()
     {
@@ -255,13 +268,9 @@ public function getDefaults()
      *
      * @param string $uriPattern
      * @return void
-     * @throws \InvalidArgumentException
      */
-    public function setUriPattern($uriPattern)
+    public function setUriPattern(string $uriPattern)
     {
-        if (!is_string($uriPattern)) {
-            throw new \InvalidArgumentException(sprintf('URI Pattern must be of type string, %s given.', gettype($uriPattern)), 1223499724);
-        }
         $this->uriPattern = $uriPattern;
         $this->isParsed = false;
     }
@@ -334,7 +343,7 @@ public function getAppendExceedingArguments()
      * Usage: setRoutePartsConfiguration(array('@controller' =>
      *            array('handler' => \Neos\Package\Subpackage\MyRoutePartHandler::class)));
      *
-     * @param array $routePartsConfiguration Route Parts configuration options
+     * @param array<string,array<mixed>> $routePartsConfiguration Route Parts configuration options
      * @return void
      */
     public function setRoutePartsConfiguration(array $routePartsConfiguration)
@@ -345,7 +354,7 @@ public function setRoutePartsConfiguration(array $routePartsConfiguration)
     /**
      * Returns the route parts configuration of this route
      *
-     * @return array $routePartsConfiguration
+     * @return array<string,array<mixed>> $routePartsConfiguration
      */
     public function getRoutePartsConfiguration()
     {
@@ -356,7 +365,7 @@ public function getRoutePartsConfiguration()
      * Limits the HTTP verbs that are accepted by this route.
      * If empty all HTTP verbs are accepted
      *
-     * @param array $httpMethods non-associative array in the format array('GET', 'POST', ...)
+     * @param list<string> $httpMethods non-associative array in the format array('GET', 'POST', ...)
      * @return void
      */
     public function setHttpMethods(array $httpMethods)
@@ -365,7 +374,7 @@ public function setHttpMethods(array $httpMethods)
     }
 
     /**
-     * @return array
+     * @return list<string>
      */
     public function getHttpMethods()
     {
@@ -405,7 +414,7 @@ public function hasHttpMethodConstraints()
     /**
      * Returns an array with the Route match results.
      *
-     * @return array An array of Route Parts and their values for further handling by the Router
+     * @return ?array<mixed> An array of Route Parts and their values for further handling by the Router
      * @see \Neos\Flow\Mvc\Routing\Router
      */
     public function getMatchResults()
@@ -436,7 +445,7 @@ public function getMatchedLifetime(): ?RouteLifetime
     /**
      * Returns the merged UriConstraints of all Route Parts after resolving, or NULL if no constraints were set yet
      *
-     * @return UriConstraints|null
+     * @return ?UriConstraints
      */
     public function getResolvedUriConstraints()
     {
@@ -471,6 +480,7 @@ public function getResolvedLifetime(): ?RouteLifetime
      * @param RouteContext $routeContext The Route Context containing the current HTTP request object and, optional, Routing RouteParameters
      * @return boolean true if this Route corresponds to the given $routeContext, otherwise false
      * @throws InvalidRoutePartValueException
+     * @phpstan-assert-if-true array<mixed> $this->getMatchResults()
      * @see getMatchResults()
      */
     public function matches(RouteContext $routeContext)
@@ -516,9 +526,11 @@ public function matches(RouteContext $routeContext)
                 $routeMatches = true;
                 $routePartValue = $matchResult->getMatchedValue();
                 if ($matchResult->hasTags()) {
+                    /** @phpstan-ignore method.nonObject (already set) */
                     $this->matchedTags = $this->matchedTags->merge($matchResult->getTags());
                 }
                 if ($matchResult->hasLifetime()) {
+                    /** @phpstan-ignore method.nonObject (already set) */
                     $this->matchedLifetime = $this->matchedLifetime->merge($matchResult->getLifetime());
                 }
             } else {
@@ -539,7 +551,11 @@ public function matches(RouteContext $routeContext)
                 if ($this->containsObject($routePartValue)) {
                     throw new InvalidRoutePartValueException('RoutePart::getValue() must only return simple types after calling RoutePart::match(). RoutePart "' . get_class($routePart) . '" returned one or more objects in Route "' . $this->getName() . '".');
                 }
-                $matchResults = Arrays::setValueByPath($matchResults, $routePart->getName(), $routePartValue);
+                $routePartName = $routePart->getName();
+                if ($routePartName === null) {
+                    throw new \Exception('Missing name for route part', 1744323723);
+                }
+                $matchResults = Arrays::setValueByPath($matchResults, $routePartName, $routePartValue);
             }
         }
         if (strlen($routePath) > 0) {
@@ -558,6 +574,7 @@ public function matches(RouteContext $routeContext)
      *
      * @param ResolveContext $resolveContext context for this resolve invokation
      * @return boolean true if this Route corresponds to the given $routeValues, otherwise false
+     * @phpstan-assert-if-true UriConstraints $this->getResolvedUriConstraints()
      * @throws InvalidRoutePartValueException
      */
     public function resolves(ResolveContext $resolveContext)
@@ -592,12 +609,15 @@ public function resolves(ResolveContext $resolveContext)
                 $hasRoutePartValue = true;
                 $routePartValue = $resolveResult->getResolvedValue();
                 if ($resolveResult->hasUriConstraints()) {
+                    /** @phpstan-ignore method.nonObject (already set) */
                     $this->resolvedUriConstraints = $this->resolvedUriConstraints->merge($resolveResult->getUriConstraints());
                 }
                 if ($resolveResult->hasTags()) {
+                    /** @phpstan-ignore method.nonObject (already set) */
                     $this->resolvedTags = $this->resolvedTags->merge($resolveResult->getTags());
                 }
                 if ($resolveResult->hasLifetime()) {
+                    /** @phpstan-ignore method.nonObject (already set) */
                     $this->resolvedLifetime = $this->resolvedLifetime->merge($resolveResult->getLifetime());
                 }
             } else {
@@ -619,7 +639,7 @@ public function resolves(ResolveContext $resolveContext)
                 $requireOptionalRouteParts = false;
                 continue;
             }
-            if ($hasRoutePartValue && strtolower($routePartValue) !== strtolower($routePartDefaultValue)) {
+            if ($hasRoutePartValue && strtolower($routePartValue ?: '') !== strtolower($routePartDefaultValue ?: '')) {
                 $matchingOptionalUriPortion .= $routePartValue;
                 $requireOptionalRouteParts = true;
             } else {
@@ -648,10 +668,12 @@ public function resolves(ResolveContext $resolveContext)
                 }
                 $routeValues = $internalArguments;
             }
+            /** @phpstan-ignore method.nonObject (already set) */
             $this->resolvedUriConstraints = $this->resolvedUriConstraints->withAddedQueryValues($routeValues);
         }
 
         if (!empty($resolvedUriPath)) {
+            /** @phpstan-ignore method.nonObject (already set) */
             $this->resolvedUriConstraints = $this->resolvedUriConstraints->withPath($resolvedUriPath);
         }
         return true;
@@ -664,8 +686,8 @@ public function resolves(ResolveContext $resolveContext)
      * If a value exists but is not equal to is corresponding default,
      * iteration is interrupted and false is returned.
      *
-     * @param array $defaults
-     * @param array $routeValues
+     * @param array<mixed> $defaults
+     * @param array<mixed> $routeValues
      * @return boolean false if one of the $routeValues is not equal to it's default value. Otherwise true
      */
     protected function compareAndRemoveMatchingDefaultValues(array $defaults, array &$routeValues)
@@ -700,8 +722,8 @@ protected function compareAndRemoveMatchingDefaultValues(array $defaults, array
      * Removes all internal arguments (prefixed with two underscores) from the given $arguments
      * and returns them as array
      *
-     * @param array $arguments
-     * @return array the internal arguments
+     * @param array<mixed> $arguments
+     * @return array<mixed> the internal arguments
      */
     protected function extractInternalArguments(array &$arguments)
     {
@@ -813,6 +835,9 @@ public function parse()
                         /** @var DynamicRoutePartInterface $lastRoutePart */
                         $lastRoutePart->setSplitString($routePartName);
                     }
+                    break;
+                default:
+                    continue 2;
             }
             $routePart->setName($routePartName);
             if ($currentRoutePartIsOptional) {
diff --git a/Neos.Flow/Classes/Mvc/Routing/RoutePartInterface.php b/Neos.Flow/Classes/Mvc/Routing/RoutePartInterface.php
index 1d5266651b..016a00efa1 100644
--- a/Neos.Flow/Classes/Mvc/Routing/RoutePartInterface.php
+++ b/Neos.Flow/Classes/Mvc/Routing/RoutePartInterface.php
@@ -34,7 +34,7 @@ public function setName($partName);
     /**
      * Returns name of the Route Part.
      *
-     * @return string
+     * @return ?string
      */
     public function getName();
 
@@ -108,13 +108,13 @@ public function isLowerCase();
      * Defines options for this Route Part.
      * Options can be used to enrich a route part with parameters or settings like case sensivitity.
      *
-     * @param array $options
+     * @param array<mixed> $options
      * @return void
      */
     public function setOptions(array $options);
 
     /**
-     * @return array options of this Route Part.
+     * @return array<mixed> options of this Route Part.
      */
     public function getOptions();
 
@@ -135,7 +135,7 @@ public function match(&$routePath);
      * removes resolved elements from $routeValues-Array.
      * This is why $routeValues has to be passed by reference.
      *
-     * @param array &$routeValues An array with key/value pairs to be resolved by Dynamic Route Parts.
+     * @param array<mixed> &$routeValues An array with key/value pairs to be resolved by Dynamic Route Parts.
      * @return bool|ResolveResult true or an instance of ResolveResult if Route Part can resolve one or more $routeValues elements, otherwise false.
      */
     public function resolve(array &$routeValues);
diff --git a/Neos.Flow/Classes/Mvc/Routing/Router.php b/Neos.Flow/Classes/Mvc/Routing/Router.php
index d72bcd6f6a..60c3a0a358 100644
--- a/Neos.Flow/Classes/Mvc/Routing/Router.php
+++ b/Neos.Flow/Classes/Mvc/Routing/Router.php
@@ -76,7 +76,7 @@ public function injectLogger(LoggerInterface $logger)
      * route could be found.
      *
      * @param RouteContext $routeContext The Route Context containing the current HTTP Request and, optional, Routing RouteParameters
-     * @return array The results of the matching route or NULL if no route matched
+     * @return array<mixed> The results of the matching route or NULL if no route matched
      * @throws InvalidRouteSetupException
      * @throws NoMatchingRouteException if no route matched the given $routeContext
      * @throws InvalidRoutePartValueException
@@ -109,7 +109,7 @@ public function route(RouteContext $routeContext): array
      * Returns the route that has been matched with the last route() call.
      * Returns NULL if no route matched or route() has not been called yet
      *
-     * @return Route
+     * @return ?Route
      */
     public function getLastMatchedRoute()
     {
@@ -151,7 +151,7 @@ public function resolve(ResolveContext $resolveContext): UriInterface
      * Returns the route that has been resolved with the last resolve() call.
      * Returns NULL if no route was found or resolve() has not been called yet
      *
-     * @return Route
+     * @return ?Route
      */
     public function getLastResolvedRoute()
     {
diff --git a/Neos.Flow/Classes/Mvc/Routing/RouterCachingService.php b/Neos.Flow/Classes/Mvc/Routing/RouterCachingService.php
index e9d5c7e89e..335f87c1c5 100644
--- a/Neos.Flow/Classes/Mvc/Routing/RouterCachingService.php
+++ b/Neos.Flow/Classes/Mvc/Routing/RouterCachingService.php
@@ -65,6 +65,12 @@ class RouterCachingService
 
     /**
      * @Flow\InjectConfiguration("mvc.routes")
+     * @phpstan-var array<string,bool|array{
+     *     position?: string,
+     *     variables?: array<string,mixed>,
+     *     providerFactory?: class-string<RoutesProviderFactoryInterface>,
+     *     providerOptions?: array<string,mixed>,
+     * }> indexed by package key
      * @var array
      */
     protected $routingSettings;
@@ -72,7 +78,7 @@ class RouterCachingService
     /**
      * @param LoggerInterface $logger
      */
-    public function injectLogger(LoggerInterface $logger)
+    public function injectLogger(LoggerInterface $logger): void
     {
         $this->logger = $logger;
     }
@@ -93,7 +99,7 @@ public function initializeObject()
      * Checks the cache for the given RouteContext and returns the result or false if no matching ache entry was found
      *
      * @param RouteContext $routeContext
-     * @return array|false the cached route values or false if no cache entry was found
+     * @return array<mixed>|false the cached route values or false if no cache entry was found
      */
     public function getCachedMatchResults(RouteContext $routeContext)
     {
@@ -109,7 +115,7 @@ public function getCachedMatchResults(RouteContext $routeContext)
      * Stores the $matchResults in the cache
      *
      * @param RouteContext $routeContext
-     * @param array $matchResults
+     * @param array<mixed> $matchResults
      * @param RouteTags|null $matchedTags
      * @param RouteLifetime|null $matchedLifetime
      * @return void
@@ -170,8 +176,8 @@ public function storeResolvedUriConstraints(ResolveContext $resolveContext, UriC
 
     /**
      * @param string $uriPath
-     * @param array $routeValues
-     * @return array
+     * @param array<mixed> $routeValues
+     * @return array<int,string>
      */
     protected function generateRouteTags($uriPath, $routeValues)
     {
@@ -259,8 +265,8 @@ protected function containsObject($subject)
     /**
      * Recursively converts objects in an array to their identifiers
      *
-     * @param array $routeValues the array to be processed
-     * @return array|null the modified array or NULL if $routeValues contain an object and its identifier could not be determined
+     * @param array<mixed> $routeValues the array to be processed
+     * @return array<mixed>|null the modified array or NULL if $routeValues contain an object and its identifier could not be determined
      */
     protected function convertObjectsToHashes(array $routeValues)
     {
@@ -289,7 +295,7 @@ protected function convertObjectsToHashes(array $routeValues)
      * Generates the Resolve cache identifier for the given Request
      *
      * @param ResolveContext $resolveContext
-     * @param array $routeValues
+     * @param array<mixed> $routeValues
      * @return string
      */
     protected function buildResolveCacheIdentifier(ResolveContext $resolveContext, array $routeValues)
@@ -303,8 +309,8 @@ protected function buildResolveCacheIdentifier(ResolveContext $resolveContext, a
      * Helper method to generate tags by taking all UUIDs contained
      * in the given $routeValues or $matchResults
      *
-     * @param array $values
-     * @return array
+     * @param array<mixed> $values
+     * @return array<int,string>
      */
     protected function extractUuids(array $values)
     {
diff --git a/Neos.Flow/Classes/Mvc/Routing/RouterInterface.php b/Neos.Flow/Classes/Mvc/Routing/RouterInterface.php
index 8aebb7e108..e2596510f0 100644
--- a/Neos.Flow/Classes/Mvc/Routing/RouterInterface.php
+++ b/Neos.Flow/Classes/Mvc/Routing/RouterInterface.php
@@ -26,7 +26,7 @@ interface RouterInterface
      * Returns the matchResults of the matching route.
      *
      * @param RouteContext $routeContext The Route Context containing the current HTTP Request and, optional, Routing RouteParameters
-     * @return array The results of the matching route
+     * @return array<mixed> The results of the matching route
      * @throws NoMatchingRouteException if no route matched the $routeContext
      */
     public function route(RouteContext $routeContext): array;
diff --git a/Neos.Flow/Classes/Mvc/Routing/Routes.php b/Neos.Flow/Classes/Mvc/Routing/Routes.php
index cc0822c971..66e14d2c94 100644
--- a/Neos.Flow/Classes/Mvc/Routing/Routes.php
+++ b/Neos.Flow/Classes/Mvc/Routing/Routes.php
@@ -21,7 +21,7 @@ final class Routes implements \IteratorAggregate
     private function __construct(
         Route ...$routes
     ) {
-        $this->routes = $routes;
+        $this->routes = array_values($routes);
 
         // validate that each route is unique
         $routesWithHttpMethodConstraints = [];
@@ -46,6 +46,18 @@ public static function create(Route ...$routes): self
         return new self(...$routes);
     }
 
+    /**
+     * @param array<array{
+     *      name?: string,
+     *      uriPattern: string,
+     *      defaults?: array<mixed>,
+     *      routeParts?: array<mixed>,
+     *      toLowerCase?: bool,
+     *      appendExceedingArguments?: bool,
+     *      cache?: array{lifetime?: int, tags?: array<mixed>},
+     *      httpMethods?: list<string>
+     *  }> $configuration
+     */
     public static function fromConfiguration(array $configuration): self
     {
         $routes = [];
diff --git a/Neos.Flow/Classes/Mvc/Routing/StaticRoutePart.php b/Neos.Flow/Classes/Mvc/Routing/StaticRoutePart.php
index 9e33c527f5..16970d5018 100644
--- a/Neos.Flow/Classes/Mvc/Routing/StaticRoutePart.php
+++ b/Neos.Flow/Classes/Mvc/Routing/StaticRoutePart.php
@@ -21,7 +21,7 @@ class StaticRoutePart extends \Neos\Flow\Mvc\Routing\AbstractRoutePart
     /**
      * Gets default value of the Route Part.
      *
-     * @return string
+     * @return ?string
      */
     public function getDefaultValue()
     {
@@ -37,7 +37,6 @@ public function getDefaultValue()
      */
     public function match(&$routePath)
     {
-        $routePath = (string)$routePath;
         $this->value = null;
         if ($this->name === null || $this->name === '') {
             return false;
@@ -57,7 +56,7 @@ public function match(&$routePath)
     /**
      * Sets the Route Part value to the Route Part name and returns true if successful.
      *
-     * @param array $routeValues not used but needed to implement \Neos\Flow\Mvc\Routing\AbstractRoutePart
+     * @param array<mixed> $routeValues not used but needed to implement \Neos\Flow\Mvc\Routing\AbstractRoutePart
      * @return boolean
      */
     public function resolve(array &$routeValues)
diff --git a/Neos.Flow/Classes/Mvc/Routing/TestingRoutesProvider.php b/Neos.Flow/Classes/Mvc/Routing/TestingRoutesProvider.php
index e20be3c46b..b7168b74da 100644
--- a/Neos.Flow/Classes/Mvc/Routing/TestingRoutesProvider.php
+++ b/Neos.Flow/Classes/Mvc/Routing/TestingRoutesProvider.php
@@ -36,7 +36,7 @@ public function __construct(
      *
      * @internal Please use {@see FunctionalTestCase::registerRoute} instead.
      */
-    public function addRoute(Route $route)
+    public function addRoute(Route $route): void
     {
         // we prepended the route, like the old Router::addRoute
         $this->additionalRoutes = Routes::create($route)->merge($this->additionalRoutes);
diff --git a/Neos.Flow/Classes/Mvc/Routing/UriBuilder.php b/Neos.Flow/Classes/Mvc/Routing/UriBuilder.php
index c31ed58424..4600ad1c85 100644
--- a/Neos.Flow/Classes/Mvc/Routing/UriBuilder.php
+++ b/Neos.Flow/Classes/Mvc/Routing/UriBuilder.php
@@ -51,13 +51,13 @@ class UriBuilder
     protected $request;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $arguments = [];
 
     /**
      * Arguments which have been used for building the last URI
-     * @var array
+     * @var array<mixed>
      */
     protected $lastArguments = [];
 
@@ -78,7 +78,7 @@ class UriBuilder
     protected $addQueryString = false;
 
     /**
-     * @var array
+     * @var array<mixed>
      * @deprecated with Flow 9.0
      */
     protected $argumentsToBeExcludedFromQueryString = [];
@@ -117,7 +117,7 @@ public function getRequest()
      * If you want to "prefix" arguments, you can pass in multidimensional arrays:
      * array('prefix1' => array('foo' => 'bar')) gets "&prefix1[foo]=bar"
      *
-     * @param array $arguments
+     * @param array<mixed> $arguments
      * @return UriBuilder the current UriBuilder to allow method chaining
      * @api
      */
@@ -128,7 +128,7 @@ public function setArguments(array $arguments)
     }
 
     /**
-     * @return array
+     * @return array<mixed>
      * @api
      */
     public function getArguments()
@@ -228,7 +228,7 @@ public function getAddQueryString()
      * A list of arguments to be excluded from the query parameters
      * Only active if addQueryString is set
      *
-     * @param array $argumentsToBeExcludedFromQueryString
+     * @param array<mixed> $argumentsToBeExcludedFromQueryString
      * @return UriBuilder the current UriBuilder to allow method chaining
      * @deprecated with Flow 9.0
      */
@@ -239,7 +239,7 @@ public function setArgumentsToBeExcludedFromQueryString(array $argumentsToBeExcl
     }
 
     /**
-     * @return array
+     * @return array<mixed>
      * @deprecated with Flow 9.0
      */
     public function getArgumentsToBeExcludedFromQueryString()
@@ -251,7 +251,7 @@ public function getArgumentsToBeExcludedFromQueryString()
      * Returns the arguments being used for the last URI being built.
      * This is only set after build() / uriFor() has been called.
      *
-     * @return array The last arguments
+     * @return array<mixed> The last arguments
      */
     public function getLastArguments()
     {
@@ -330,9 +330,9 @@ public function uriFor(string $actionName, array $controllerArguments = [], ?str
      *    )
      * )
      *
-     * @param array $arguments arguments
+     * @param array<mixed> $arguments arguments
      * @param ActionRequest $currentRequest
-     * @return array arguments with namespace
+     * @return array<mixed> arguments with namespace
      */
     protected function addNamespaceToArguments(array $arguments, ActionRequest $currentRequest)
     {
@@ -349,7 +349,7 @@ protected function addNamespaceToArguments(array $arguments, ActionRequest $curr
     /**
      * Builds the URI
      *
-     * @param array $arguments optional URI arguments. Will be merged with $this->arguments with precedence to $arguments
+     * @param array<mixed> $arguments optional URI arguments. Will be merged with $this->arguments with precedence to $arguments
      * @return string the (absolute or relative) URI as string
      * @throws \Neos\Flow\Http\Exception
      * @api
@@ -389,8 +389,8 @@ public function build(array $arguments = [])
      * The request hierarchy is structured as follows:
      * root (HTTP) > main (Action) > sub (Action) > sub sub (Action)
      *
-     * @param array $arguments
-     * @return array
+     * @param array<mixed> $arguments
+     * @return array<mixed>
      */
     protected function mergeArgumentsWithRequestArguments(array $arguments)
     {
diff --git a/Neos.Flow/Classes/Mvc/View/AbstractView.php b/Neos.Flow/Classes/Mvc/View/AbstractView.php
index 86a8bc08d4..8dbc80139e 100644
--- a/Neos.Flow/Classes/Mvc/View/AbstractView.php
+++ b/Neos.Flow/Classes/Mvc/View/AbstractView.php
@@ -31,7 +31,7 @@ abstract class AbstractView implements ViewInterface
      *         ...
      *     )
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $supportedOptions = [];
 
@@ -39,13 +39,13 @@ abstract class AbstractView implements ViewInterface
      * The configuration options of this view
      * @see $supportedOptions
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $options = [];
 
     /**
      * View variables and their values
-     * @var array
+     * @var array<string,mixed>
      * @see assign()
      */
     protected $variables = [];
@@ -60,7 +60,7 @@ abstract class AbstractView implements ViewInterface
     /**
      * Factory method to create an instance with given options.
      *
-     * @param array $options
+     * @param array<mixed> $options
      * @return static
      */
     public static function createWithOptions(array $options): self
@@ -71,7 +71,7 @@ public static function createWithOptions(array $options): self
     /**
      * Set default options based on the supportedOptions provided
      *
-     * @param array $options
+     * @param array<mixed> $options
      * @throws Exception
      */
     public function __construct(array $options = [])
@@ -155,7 +155,7 @@ public function assign(string $key, mixed $value): self
     /**
      * Add multiple variables to $this->variables.
      *
-     * @param array $values array in the format array(key1 => value1, key2 => value2)
+     * @param array<string,mixed> $values array in the format array(key1 => value1, key2 => value2)
      * @return $this for chaining
      * @api
      */
diff --git a/Neos.Flow/Classes/Mvc/View/JsonView.php b/Neos.Flow/Classes/Mvc/View/JsonView.php
index a614500bee..22a6c15e47 100644
--- a/Neos.Flow/Classes/Mvc/View/JsonView.php
+++ b/Neos.Flow/Classes/Mvc/View/JsonView.php
@@ -40,7 +40,7 @@ class JsonView extends AbstractView
 
     /**
      * Supported options
-     * @var array
+     * @var array<string,array<mixed>>
      */
     protected $supportedOptions = [
         'jsonEncodingOptions' => [0, 'Bitmask of supported Encoding options. See https://php.net/manual/en/json.constants.php', 'integer'],
@@ -66,7 +66,7 @@ class JsonView extends AbstractView
     /**
      * Only variables whose name is contained in this array will be rendered
      *
-     * @var array
+     * @var array<string>
      */
     protected $variablesToRender = ['value'];
 
@@ -166,7 +166,7 @@ class JsonView extends AbstractView
      * {"customer":{"firstName":"John","__class":"Customer"}}
      * This might be of interest to not provide information about the package or domain structure behind.
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected $configuration = [];
 
@@ -180,7 +180,7 @@ class JsonView extends AbstractView
      * Specifies which variables this JsonView should render
      * By default only the variable 'value' will be rendered
      *
-     * @param array $variablesToRender
+     * @param array<string> $variablesToRender
      * @return void
      * @api
      */
@@ -190,7 +190,7 @@ public function setVariablesToRender(array $variablesToRender)
     }
 
     /**
-     * @param array $configuration The rendering configuration for this JSON view
+     * @param array<string,mixed> $configuration The rendering configuration for this JSON view
      * @return void
      */
     public function setConfiguration(array $configuration)
@@ -220,7 +220,7 @@ public function render(): ResponseInterface
      * Loads the configuration and transforms the value to a serializable
      * array.
      *
-     * @return array|string|int|float|null An array containing the values, ready to be JSON encoded
+     * @return array<mixed>|string|int|float|null An array containing the values, ready to be JSON encoded
      * @api
      */
     protected function renderArray()
@@ -244,12 +244,12 @@ protected function renderArray()
      * supplied configuration.
      *
      * @param mixed $value The value to transform
-     * @param array $configuration Configuration for transforming the value
-     * @return array|string|int|float|null The transformed value
+     * @param array<string,mixed> $configuration Configuration for transforming the value
+     * @return array<mixed>|string|int|float|null The transformed value
      */
     protected function transformValue($value, array $configuration)
     {
-        if (is_array($value) || $value instanceof \ArrayAccess) {
+        if (is_iterable($value)) {
             $array = [];
             foreach ($value as $key => $element) {
                 if (isset($configuration['_descendAll']) && is_array($configuration['_descendAll'])) {
@@ -279,8 +279,8 @@ protected function transformValue($value, array $configuration)
      * array structure.
      *
      * @param object $object Object to traverse
-     * @param array $configuration Configuration for transforming the given object
-     * @return array|string Object structure as an array
+     * @param array<string,mixed> $configuration Configuration for transforming the given object
+     * @return array<mixed>|string Object structure as an array
      */
     protected function transformObject($object, array $configuration)
     {
diff --git a/Neos.Flow/Classes/Mvc/View/SimpleTemplateView.php b/Neos.Flow/Classes/Mvc/View/SimpleTemplateView.php
index 5454cea8e8..77a853b856 100644
--- a/Neos.Flow/Classes/Mvc/View/SimpleTemplateView.php
+++ b/Neos.Flow/Classes/Mvc/View/SimpleTemplateView.php
@@ -25,7 +25,7 @@ class SimpleTemplateView extends AbstractView
     use StreamFactoryTrait;
 
     /**
-     * @var array
+     * @var array<string,array<mixed>>
      */
     protected $supportedOptions = [
         'templateSource' => ['', 'Source of the template to render', 'string'],
diff --git a/Neos.Flow/Classes/Mvc/ViewConfigurationManager.php b/Neos.Flow/Classes/Mvc/ViewConfigurationManager.php
index 3ea598ec72..3079b8b8e1 100644
--- a/Neos.Flow/Classes/Mvc/ViewConfigurationManager.php
+++ b/Neos.Flow/Classes/Mvc/ViewConfigurationManager.php
@@ -53,7 +53,11 @@ class ViewConfigurationManager
      * an array of options that will be set on the view object.
      *
      * @param ActionRequest $request
-     * @return array
+     * @return array{
+     *     requestFilter?: string,
+     *     viewObjectName?: string,
+     *     options?: array<string,mixed>
+     * }
      */
     public function getViewConfiguration(ActionRequest $request)
     {
@@ -61,6 +65,13 @@ public function getViewConfiguration(ActionRequest $request)
 
         $viewConfiguration = $this->cache->get($cacheIdentifier);
         if ($viewConfiguration === false) {
+            /**
+             * @var array<int,array{
+             *     requestFilter?: string,
+             *     viewObjectName?: string,
+             *     options?: array<string,mixed>
+             * }> $configurations
+             */
             $configurations = $this->configurationManager->getConfiguration('Views');
 
             $requestMatcher = new RequestMatcher($request);
diff --git a/Neos.Flow/Classes/ObjectManagement/CompileTimeObjectManager.php b/Neos.Flow/Classes/ObjectManagement/CompileTimeObjectManager.php
index 8f678fe7ee..e04e6513db 100644
--- a/Neos.Flow/Classes/ObjectManagement/CompileTimeObjectManager.php
+++ b/Neos.Flow/Classes/ObjectManagement/CompileTimeObjectManager.php
@@ -17,6 +17,7 @@
 use Neos\Flow\Configuration\ConfigurationManager;
 use Neos\Flow\Configuration\Exception\InvalidConfigurationTypeException;
 use Neos\Flow\ObjectManagement\Configuration\Configuration;
+use Neos\Flow\ObjectManagement\Configuration\ConfigurationArgument;
 use Neos\Flow\ObjectManagement\Configuration\ConfigurationBuilder;
 use Neos\Flow\ObjectManagement\Configuration\ConfigurationProperty as Property;
 use Neos\Flow\Annotations as Flow;
@@ -25,6 +26,7 @@
 use Neos\Flow\ObjectManagement\Exception\WrongScopeException;
 use Neos\Flow\Package\FlowPackageInterface;
 use Neos\Flow\Package\PackageInterface;
+use Neos\Flow\Package\PackageKeyAwareInterface;
 use Neos\Flow\Reflection\ReflectionService;
 use Psr\Log\LoggerInterface;
 
@@ -33,6 +35,8 @@
  * singleton scoped objects. This Object Manager is used during compile time when the proxy
  * class based DI mechanism is not yet available.
  *
+ * @template ObjectRecordInstance of object
+ * @extends ObjectManager<ObjectRecordInstance>
  * @Flow\Scope("singleton")
  * @Flow\Proxy(false)
  */
@@ -59,24 +63,24 @@ class CompileTimeObjectManager extends ObjectManager
     protected ?LoggerInterface $logger;
 
     /**
-     * @var array
+     * @var array<class-string,Configuration>
      */
     protected array $objectConfigurations = [];
 
     /**
      * A list of all class names known to the Object Manager
      *
-     * @var array
+     * @var array<string,array<int,class-string>>
      */
     protected array $registeredClassNames = [];
 
     /**
-     * @var array
+     * @var array<string>
      */
     protected array $objectNameBuildStack = [];
 
     /**
-     * @var array
+     * @var array<int,array<int,class-string|"">>
      */
     protected array $cachedClassNamesByScope = [];
 
@@ -123,7 +127,7 @@ public function injectLogger(LoggerInterface $logger): void
     /**
      * Initializes the object configurations and some other parts of this Object Manager.
      *
-     * @param PackageInterface[] $packages An array of active packages to consider
+     * @param array<PackageInterface&PackageKeyAwareInterface> $packages An array of active packages to consider
      * @return void
      * @throws InvalidConfigurationTypeException
      * @throws InvalidObjectConfigurationException
@@ -132,17 +136,46 @@ public function injectLogger(LoggerInterface $logger): void
     public function initialize(array $packages): void
     {
         $this->registeredClassNames = $this->registerClassFiles($packages);
-        $this->reflectionService->buildReflectionData($this->registeredClassNames);
-
-        $rawCustomObjectConfigurations = $this->configurationManager->getConfiguration(ConfigurationManager::CONFIGURATION_TYPE_OBJECTS);
+        $this->reflectionService?->buildReflectionData($this->registeredClassNames);
+
+        /**
+         * @var array<string,array<string,array{
+         *     className?: class-string,
+         *     scope?: string,
+         *     factoryObjectName?: class-string,
+         *     factoryMethodName?: string,
+         *     arguments?: array<mixed>,
+         *     properties?: array<string,array{
+         *         object?: class-string|array{
+         *             factoryObjectName: class-string,
+         *             factoryMethodName?: string,
+         *             arguments?: array<mixed>
+         *         }
+         *     }>,
+         * }>> $rawCustomObjectConfigurations
+         */
+        $rawCustomObjectConfigurations = $this->configurationManager?->getConfiguration(ConfigurationManager::CONFIGURATION_TYPE_OBJECTS) ?: [];
 
         $configurationBuilder = new ConfigurationBuilder();
-        $configurationBuilder->injectReflectionService($this->reflectionService);
-        $configurationBuilder->injectLogger($this->logger);
-        $configurationBuilder->injectExcludeClassesFromConstructorAutowiring($this->configurationManager->getConfiguration(ConfigurationManager::CONFIGURATION_TYPE_SETTINGS, 'Neos.Flow.object.dependencyInjection.excludeClassesFromConstructorAutowiring'));
-
-        $this->objectConfigurations = $configurationBuilder->buildObjectConfigurations($this->registeredClassNames, $rawCustomObjectConfigurations);
-
+        if ($this->reflectionService) {
+            $configurationBuilder->injectReflectionService($this->reflectionService);
+        }
+        if ($this->logger) {
+            $configurationBuilder->injectLogger($this->logger);
+        }
+        $configurationBuilder->injectExcludeClassesFromConstructorAutowiring(
+            $this->configurationManager?->getConfiguration(
+                ConfigurationManager::CONFIGURATION_TYPE_SETTINGS,
+                'Neos.Flow.object.dependencyInjection.excludeClassesFromConstructorAutowiring'
+            ) ?: []
+        );
+
+        $this->objectConfigurations = $configurationBuilder->buildObjectConfigurations(
+            $this->registeredClassNames,
+            $rawCustomObjectConfigurations
+        );
+
+        /** @phpstan-ignore argument.type (@todo revisit array shapes) */
         $this->setObjects($this->buildObjectsArray());
     }
 
@@ -162,6 +195,7 @@ public function initialize(array $packages): void
     public function setInstance($objectName, $instance): void
     {
         if ($this->registeredClassNames === []) {
+            /** @phpstan-ignore assign.propertyType (classical subtype problem) */
             $this->objects[$objectName][self::KEY_INSTANCE] = $instance;
         } else {
             parent::setInstance($objectName, $instance);
@@ -171,7 +205,7 @@ public function setInstance($objectName, $instance): void
     /**
      * Returns a list of all class names, grouped by package key,  which were registered by registerClassFiles()
      *
-     * @return array
+     * @return array<string,array<int,class-string>>
      */
     public function getRegisteredClassNames(): array
     {
@@ -182,7 +216,7 @@ public function getRegisteredClassNames(): array
      * Returns a list of class names, which are configured with the given scope
      *
      * @param integer $scope One of the ObjectConfiguration::SCOPE_ constants
-     * @return array An array of class names configured with the given scope
+     * @return array<int,class-string> An array of class names configured with the given scope
      */
     public function getClassNamesByScope(int $scope): array
     {
@@ -192,11 +226,13 @@ public function getClassNamesByScope(int $scope): array
                     if (isset($information[self::KEY_CLASS_NAME])) {
                         $this->cachedClassNamesByScope[$scope][] = $information[self::KEY_CLASS_NAME];
                     } else {
+                        /** @phpstan-ignore assign.propertyType (I guess this is a class name here) */
                         $this->cachedClassNamesByScope[$scope][] = $objectName;
                     }
                 }
             }
         }
+        /** @phpstan-ignore return.type (@todo check class-string vs. string) */
         return $this->cachedClassNamesByScope[$scope];
     }
 
@@ -207,8 +243,8 @@ public function getClassNamesByScope(int $scope): array
      *
      * For performance reasons this function ignores classes whose name ends with "Exception".
      *
-     * @param array $packages A list of packages to consider
-     * @return array A list of class names which were discovered in the given packages
+     * @param array<PackageInterface&PackageKeyAwareInterface> $packages A list of packages to consider
+     * @return array<string,array<int,class-string>> A list of class names which were discovered in the given packages
      *
      * @throws InvalidConfigurationTypeException
      */
@@ -222,7 +258,9 @@ protected function registerClassFiles(array $packages): array
 
             $includeClassesConfiguration = $this->allSettings['Neos']['Flow']['object']['includeClasses'];
         }
+        /** @var array<string,array<int,string>> $includeClassesConfiguration */
 
+        /** @var array<string,array<int,class-string>> $availableClassNames */
         $availableClassNames = ['' => ['DateTime']];
 
         $shouldRegisterFunctionalTestClasses = (bool)($this->allSettings['Neos']['Flow']['object']['registerFunctionalTestClasses'] ?? false);
@@ -242,6 +280,7 @@ protected function registerClassFiles(array $packages): array
                         }
                     }
                 }
+                /** @phpstan-ignore booleanAnd.rightAlwaysTrue (can also be something else) */
                 if (isset($availableClassNames[$packageKey]) && is_array($availableClassNames[$packageKey])) {
                     $availableClassNames[$packageKey] = array_unique($availableClassNames[$packageKey]);
                 }
@@ -254,9 +293,9 @@ protected function registerClassFiles(array $packages): array
      * Given an array of class names by package key this filters out classes that
      * have been configured to be included by object management.
      *
-     * @param array $classNames 2-level array - key of first level is package key, value of second level is classname (FQN)
-     * @param array $includeClassesConfiguration array of includeClasses configurations
-     * @return array The input array with all configured to be included in object management added in
+     * @param array<string,array<int,class-string>> $classNames 2-level array - key of first level is package key, value of second level is classname (FQN)
+     * @param array<string,array<int,string>> $includeClassesConfiguration array of includeClasses configurations
+     * @return array<string,array<int,class-string>> The input array with all configured to be included in object management added in
      * @throws InvalidConfigurationTypeException
      */
     protected function filterClassNamesFromConfiguration(array $classNames, array $includeClassesConfiguration): array
@@ -267,16 +306,15 @@ protected function filterClassNamesFromConfiguration(array $classNames, array $i
     /**
      * Filters the classnames available for object management by filter expressions that includes classes.
      *
-     * @param array $classNames All classnames per package
-     * @param array $filterConfiguration The filter configuration to apply
-     * @return array the remaining class
-     * @throws InvalidConfigurationTypeException
+     * @param array<string,array<int,class-string>> $classNames All classnames per package
+     * @param array<string,mixed> $filterConfiguration The filter configuration to apply
+     * @return array<string,array<int,class-string>> the remaining class
      */
     protected function applyClassFilterConfiguration(array $classNames, array $filterConfiguration): array
     {
         foreach ($filterConfiguration as $packageKey => $filterExpressions) {
             if (!array_key_exists($packageKey, $classNames)) {
-                $this->logger->debug('The package "' . $packageKey . '" specified in the setting "Neos.Flow.object.includeClasses" was either excluded or is not loaded.');
+                $this->logger?->debug('The package "' . $packageKey . '" specified in the setting "Neos.Flow.object.includeClasses" was either excluded or is not loaded.');
                 continue;
             }
             if (!is_array($filterExpressions)) {
@@ -310,13 +348,22 @@ static function ($className) use ($filterExpression) {
      * Builds the  objects array which contains information about the registered objects,
      * their scope, class, built method etc.
      *
-     * @return array
+     * @return array<string,array{
+     *     l: string,
+     *     s: int,
+     *     p: ?string,
+     *     c?: class-string|"",
+     *     f?: array{0: string, 1: string},
+     *     fa?: array<int,array{
+     *         t: int,
+     *         v: mixed,
+     *     }>,
+     * }>
      * @throws CacheException
      */
     protected function buildObjectsArray(): array
     {
         $objects = [];
-        /* @var $objectConfiguration Configuration */
         foreach ($this->objectConfigurations as $objectConfiguration) {
             $objectName = $objectConfiguration->getObjectName();
             $objects[$objectName] = [
@@ -337,6 +384,9 @@ protected function buildObjectsArray(): array
                 $factoryMethodArguments = $objectConfiguration->getFactoryArguments();
                 if (count($factoryMethodArguments) > 0) {
                     foreach ($factoryMethodArguments as $index => $argument) {
+                        if (!$argument instanceof ConfigurationArgument) {
+                            continue;
+                        }
                         $objects[$objectName][self::KEY_FACTORY_ARGUMENTS][$index] = [
                             self::KEY_ARGUMENT_TYPE => $argument->getType(),
                             self::KEY_ARGUMENT_VALUE => $argument->getValue()
@@ -345,14 +395,14 @@ protected function buildObjectsArray(): array
                 }
             }
         }
-        $this->configurationCache->set('objects', $objects);
+        $this->configurationCache?->set('objects', $objects);
         return $objects;
     }
 
     /**
      * Returns object configurations which were previously built by the ConfigurationBuilder.
      *
-     * @return array
+     * @return array<class-string,Configuration>
      */
     public function getObjectConfigurations(): array
     {
@@ -395,7 +445,6 @@ public function get($objectName, ...$constructorArguments): object
         $this->objectNameBuildStack[] = $objectName;
 
         $object = parent::get($objectName);
-        /** @var Configuration $objectConfiguration */
         $objectConfiguration = $this->objectConfigurations[$objectName];
         foreach ($objectConfiguration->getProperties() as $propertyName => $property) {
             if ($property->getAutowiring() !== Configuration::AUTOWIRING_MODE_ON) {
@@ -407,6 +456,9 @@ public function get($objectName, ...$constructorArguments): object
                     break;
                 case Property::PROPERTY_TYPES_CONFIGURATION:
                     $propertyValue = $property->getValue();
+                    if (!$this->configurationManager) {
+                        throw new \Exception('Cannot resolve configuration property type without a configuration manager instance', 1744305311);
+                    }
                     $value = $this->configurationManager->getConfiguration($propertyValue['type'], $propertyValue['path']);
                     break;
                 case Property::PROPERTY_TYPES_OBJECT:
diff --git a/Neos.Flow/Classes/ObjectManagement/Configuration/Configuration.php b/Neos.Flow/Classes/ObjectManagement/Configuration/Configuration.php
index bb24986041..d5c055c589 100644
--- a/Neos.Flow/Classes/ObjectManagement/Configuration/Configuration.php
+++ b/Neos.Flow/Classes/ObjectManagement/Configuration/Configuration.php
@@ -12,7 +12,6 @@
  */
 
 use Neos\Flow\Annotations as Flow;
-use Neos\Flow\Configuration\Exception\InvalidConfigurationException;
 
 /**
  * Flow Object Configuration
@@ -36,13 +35,13 @@ class Configuration
 
     /**
      * Name of the class the object is based on
-     * @var string $className
+     * @var class-string|"" $className
      */
     protected $className;
 
     /**
      * Key of the package the specified object is part of
-     * @var string
+     * @var ?string
      */
     protected $packageKey;
 
@@ -60,7 +59,7 @@ class Configuration
 
     /**
      * Arguments of the factory method
-     * @var array
+     * @var array<ConfigurationArgument>
      */
     protected $factoryArguments = [];
 
@@ -71,13 +70,13 @@ class Configuration
 
     /**
      * Arguments of the constructor detected by reflection
-     * @var array
+     * @var array<ConfigurationArgument>
      */
     protected $arguments = [];
 
     /**
      * Array of properties which are injected into the object
-     * @var array
+     * @var array<ConfigurationProperty>
      */
     protected $properties = [];
 
@@ -109,7 +108,9 @@ class Configuration
      * The constructor
      *
      * @param string $objectName The unique identifier of the object
-     * @param string $className Name of the class which provides the functionality of this object
+     * @param ?class-string $className Name of the class which provides the functionality of this object
+     * @todo fix the weird test case that is the only thing ever putting null in $className,
+     * @see \Neos\Flow\Tests\Unit\ObjectManagement\Configuration\ConfigurationTest::setUp())
      */
     public function __construct($objectName, $className = null)
     {
@@ -121,7 +122,9 @@ public function __construct($objectName, $className = null)
         }
 
         $this->objectName = $objectName;
-        $this->className = ($className === null ? $objectName : $className);
+        $className = ($className === null ? $objectName : $className);
+        /** @phpstan-ignore assign.propertyType (I guess object name is a class here) */
+        $this->className = $className;
     }
 
     /**
@@ -149,7 +152,7 @@ public function getObjectName()
     /**
      * Setter function for property "className"
      *
-     * @param string $className Name of the class which provides the functionality for this object
+     * @param class-string $className Name of the class which provides the functionality for this object
      * @return void
      */
     public function setClassName($className)
@@ -160,7 +163,7 @@ public function setClassName($className)
     /**
      * Returns the class name
      *
-     * @return string Name of the implementing class of this object
+     * @return class-string|"" Name of the implementing class of this object (or empty string for some reason)
      */
     public function getClassName()
     {
@@ -181,7 +184,7 @@ public function setPackageKey($packageKey)
     /**
      * Returns the package key
      *
-     * @return string Key of the package this object is part of
+     * @return ?string Key of the package this object is part of
      */
     public function getPackageKey()
     {
@@ -221,9 +224,9 @@ public function getFactoryObjectName()
      * @return void
      * @throws \InvalidArgumentException
      */
-    public function setFactoryMethodName($methodName)
+    public function setFactoryMethodName(string $methodName)
     {
-        if (!is_string($methodName) || $methodName === '') {
+        if ($methodName === '') {
             throw new \InvalidArgumentException('No valid factory method name specified.', 1229700126);
         }
         $this->factoryMethodName = $methodName;
@@ -337,8 +340,7 @@ public function getLifecycleShutdownMethodName()
      * Setter function for injection properties. If an empty array is passed to this
      * method, all (possibly) defined properties are removed from the configuration.
      *
-     * @param array $properties Array of ConfigurationProperty
-     * @throws InvalidConfigurationException
+     * @param array<ConfigurationProperty> $properties Array of ConfigurationProperty
      * @return void
      */
     public function setProperties(array $properties)
@@ -347,11 +349,7 @@ public function setProperties(array $properties)
             $this->properties = [];
         } else {
             foreach ($properties as $value) {
-                if ($value instanceof ConfigurationProperty) {
-                    $this->setProperty($value);
-                } else {
-                    throw new InvalidConfigurationException(sprintf('Only ConfigurationProperty instances are allowed, "%s" given', is_object($value) ? get_class($value) : gettype($value)), 1449217567);
-                }
+                $this->setProperty($value);
             }
         }
     }
@@ -382,7 +380,6 @@ public function setProperty(ConfigurationProperty $property)
      * method, all (possibly) defined constructor arguments are removed from the configuration.
      *
      * @param array<ConfigurationArgument> $arguments
-     * @throws InvalidConfigurationException
      * @return void
      */
     public function setArguments(array $arguments)
@@ -391,11 +388,7 @@ public function setArguments(array $arguments)
             $this->arguments = [];
         } else {
             foreach ($arguments as $argument) {
-                if ($argument instanceof ConfigurationArgument) {
-                    $this->setArgument($argument);
-                } else {
-                    throw new InvalidConfigurationException(sprintf('Only ConfigurationArgument instances are allowed, "%s" given', is_object($argument) ? get_class($argument) : gettype($argument)), 1449217803);
-                }
+                $this->setArgument($argument);
             }
         }
     }
@@ -429,7 +422,7 @@ public function getArguments()
         for ($index = 1; $index <= $argumentsCount; $index++) {
             $sortedArguments[$index] = $this->arguments[$index] ?? null;
         }
-        return $sortedArguments;
+        return array_filter($sortedArguments);
     }
 
     /**
@@ -446,7 +439,7 @@ public function setFactoryArgument(ConfigurationArgument $argument)
     /**
      * Returns a sorted array of factory method arguments indexed by position (starting with "1")
      *
-     * @return array<ConfigurationArgument> A sorted array of ConfigurationArgument objects with the argument position as index
+     * @return array<int,?ConfigurationArgument> A sorted array of ConfigurationArgument objects with the argument position as index
      */
     public function getFactoryArguments()
     {
diff --git a/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationArgument.php b/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationArgument.php
index 89a1bb12f6..542f28b2a0 100644
--- a/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationArgument.php
+++ b/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationArgument.php
@@ -49,7 +49,7 @@ class ConfigurationArgument
     /**
      * Constructor - sets the index, value and type of the argument
      *
-     * @param string $index Index of the argument
+     * @param integer $index Index of the argument
      * @param mixed $value Value of the argument
      * @param integer $type Type of the argument - one of the argument_TYPE_* constants
      */
diff --git a/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationBuilder.php b/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationBuilder.php
index f540adb8d0..77e97f42d4 100644
--- a/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationBuilder.php
+++ b/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationBuilder.php
@@ -48,7 +48,7 @@ class ConfigurationBuilder
      * An array of object names for which constructor injection autowiring should be disabled.
      * Note that the object names are regular expressions.
      *
-     * @var array
+     * @var array<string>
      */
     protected array $excludeClassesFromConstructorAutowiring = [];
 
@@ -72,6 +72,9 @@ public function injectLogger(LoggerInterface $logger)
         $this->logger = $logger;
     }
 
+    /**
+     * @param array<string> $excludeClassesFromConstructorAutowiring
+     */
     public function injectExcludeClassesFromConstructorAutowiring(array $excludeClassesFromConstructorAutowiring): void
     {
         $this->excludeClassesFromConstructorAutowiring = $excludeClassesFromConstructorAutowiring;
@@ -83,9 +86,22 @@ public function injectExcludeClassesFromConstructorAutowiring(array $excludeClas
      * into the overall configuration. Finally autowires dependencies of arguments and properties
      * which can be resolved automatically.
      *
-     * @param array $availableClassAndInterfaceNamesByPackage An array of available class names, grouped by package key
-     * @param array $rawObjectConfigurationsByPackages An array of package keys and their raw (ie. unparsed) object configurations
-     * @return array<Configuration> Object configurations
+     * @param array<string,array<int,class-string>> $availableClassAndInterfaceNamesByPackage An array of available class names, grouped by package key
+     * @param array<string,array<string,array{
+     *      className?: class-string,
+     *      scope?: string,
+     *      factoryObjectName?: class-string,
+     *      factoryMethodName?: string,
+     *      arguments?: array<mixed>,
+     *      properties?: array<string,array{
+     *          object?: class-string|array{
+     *              factoryObjectName: class-string,
+     *              factoryMethodName?: string,
+     *              arguments?: array<mixed>
+     *          }
+     *      }>,
+     *  }|mixed>> $rawObjectConfigurationsByPackages An array of package keys and their raw (ie. unparsed) object configurations
+     * @return array<class-string,Configuration> Object configurations
      * @throws InvalidObjectConfigurationException
      */
     public function buildObjectConfigurations(array $availableClassAndInterfaceNamesByPackage, array $rawObjectConfigurationsByPackages)
@@ -102,7 +118,9 @@ public function buildObjectConfigurations(array $availableClassAndInterfaceNames
                 }
 
                 if (interface_exists($classOrInterfaceName)) {
+                    /** @var class-string $interfaceName */
                     $interfaceName = $classOrInterfaceName;
+                    /** @var class-string|false $implementationClassName */
                     $implementationClassName = $this->reflectionService->getDefaultImplementationClassNameForInterface($interfaceName);
                     if (!isset($rawObjectConfigurationsByPackages[$packageKey][$interfaceName]) && $implementationClassName === false) {
                         continue;
@@ -160,6 +178,7 @@ public function buildObjectConfigurations(array $availableClassAndInterfaceNames
                 }
 
                 if (empty($newObjectConfiguration->getClassName()) && !$newObjectConfiguration->isCreatedByFactory()) {
+                    /** @var class-string<object> $objectName */
                     $count = count($this->reflectionService->getAllImplementationClassNamesForInterface($objectName));
                     $hint = ($count ? 'It seems like there is no class which implements that interface, maybe the object configuration is obsolete?' : sprintf('There are %s classes implementing that interface, therefore you must specify a specific class in your object configuration.', $count));
                     throw new InvalidObjectConfigurationException('The object configuration for "' . $objectName . '" in the object configuration of package "' . $packageKey . '" lacks a "className" entry. ' . $hint, 1422566751);
@@ -193,9 +212,9 @@ public function buildObjectConfigurations(array $availableClassAndInterfaceNames
      * Builds a raw configuration array by parsing possible scope and autowiring
      * annotations from the given class or interface.
      *
-     * @param string $className
-     * @param array $rawObjectConfiguration
-     * @return array
+     * @param class-string $className
+     * @param array<string,mixed> $rawObjectConfiguration
+     * @return array<string,mixed>
      */
     protected function enhanceRawConfigurationWithAnnotationOptions($className, array $rawObjectConfiguration): array
     {
@@ -214,16 +233,17 @@ protected function enhanceRawConfigurationWithAnnotationOptions($className, arra
      * Builds an object configuration object from a generic configuration container.
      *
      * @param string $objectName Name of the object
-     * @param array $rawConfigurationOptions The configuration array with options for the object configuration
+     * @param array<string,mixed> $rawConfigurationOptions The configuration array with options for the object configuration
      * @param string $configurationSourceHint A human readable hint on the original source of the configuration (for troubleshooting)
-     * @param Configuration $existingObjectConfiguration If set, this object configuration object will be used instead of creating a fresh one
+     * @param ?Configuration $existingObjectConfiguration If set, this object configuration object will be used instead of creating a fresh one
      * @return Configuration The object configuration object
      * @throws InvalidObjectConfigurationException if errors occurred during parsing
      */
     protected function parseConfigurationArray($objectName, array $rawConfigurationOptions, $configurationSourceHint = '', $existingObjectConfiguration = null)
     {
+        /** @var class-string $className virtual objects without a className configuration throw an exception before */
         $className = $rawConfigurationOptions['className'] ?? $objectName;
-        $objectConfiguration = ($existingObjectConfiguration instanceof Configuration) ? $existingObjectConfiguration : new Configuration($objectName, $className);
+        $objectConfiguration = $existingObjectConfiguration ?: new Configuration($objectName, $className);
         $objectConfiguration->setConfigurationSourceHint($configurationSourceHint);
 
         foreach ($rawConfigurationOptions as $optionName => $optionValue) {
@@ -250,6 +270,9 @@ protected function parseConfigurationArray($objectName, array $rawConfigurationO
                 case 'arguments':
                     if (is_array($optionValue)) {
                         foreach ($optionValue as $argumentName => $argumentValue) {
+                            if (!is_int($argumentName)) {
+                                throw new \Exception('arguments must be indexed with integers', 1744232239);
+                            }
                             if (array_key_exists('value', $argumentValue)) {
                                 $argument = new ConfigurationArgument($argumentName, $argumentValue['value'], ConfigurationArgument::ARGUMENT_TYPES_STRAIGHTVALUE);
                             } elseif (array_key_exists('object', $argumentValue)) {
@@ -268,6 +291,10 @@ protected function parseConfigurationArray($objectName, array $rawConfigurationO
                     }
                     break;
                 case 'className':
+                    $methodName = 'set' . ucfirst($optionName);
+                    /** @phpstan-ignore argument.type (I guess the class name cannot be empty string here anymore) */
+                    $objectConfiguration->$methodName(trim((string)$optionValue));
+                    break;
                 case 'factoryObjectName':
                 case 'factoryMethodName':
                 case 'lifecycleInitializationMethodName':
@@ -346,6 +373,7 @@ protected function parsePropertyOfTypeObject($propertyName, $objectNameOrConfigu
                 if (isset($objectNameOrConfiguration['factoryObjectName']) || isset($objectNameOrConfiguration['factoryMethodName'])) {
                     $objectName = null;
                 } else {
+                    /** @phpstan-ignore argument.type (I guess we excluded "" as class name here already) */
                     $annotations = $this->reflectionService->getPropertyTagValues($parentObjectConfiguration->getClassName(), $propertyName, 'var');
                     if (count($annotations) !== 1) {
                         throw new InvalidObjectConfigurationException(sprintf('Object %s (%s), for property "%s", contains neither object name, nor factory object name, and nor is the property properly @var - annotated.', $parentObjectConfiguration->getClassName(), $parentObjectConfiguration->getConfigurationSourceHint(), $propertyName), 1297097815);
@@ -364,7 +392,7 @@ protected function parsePropertyOfTypeObject($propertyName, $objectNameOrConfigu
     /**
      * Parses the configuration for arguments of type OBJECT
      *
-     * @param string $argumentName Name of the argument
+     * @param int $argumentName index of the argument
      * @param mixed $objectNameOrConfiguration Value of the "object" section of the argument configuration - either a string or an array
      * @param string $configurationSourceHint A human readable hint on the original source of the configuration (for troubleshooting)
      * @return ConfigurationArgument A configuration argument of type object
@@ -413,14 +441,12 @@ protected function parseArgumentOfTypeObject($argumentName, $objectNameOrConfigu
      *   factoryObjectName: 'Some\Other\Factory\Class'
      *
      *
-     * @param array &$objectConfigurations
+     * @param array<Configuration> &$objectConfigurations
      * @return void
      */
     protected function wireFactoryArguments(array &$objectConfigurations)
     {
-        /** @var Configuration $objectConfiguration */
         foreach ($objectConfigurations as $objectConfiguration) {
-            /** @var ConfigurationArgument $argument */
             foreach ($objectConfiguration->getFactoryArguments() as $index => $argument) {
                 if ($argument === null || $argument->getType() !== ConfigurationArgument::ARGUMENT_TYPES_OBJECT) {
                     continue;
@@ -431,10 +457,7 @@ protected function wireFactoryArguments(array &$objectConfigurations)
                 }
                 $argumentObjectName = $objectConfiguration->getObjectName() . ':argument:' . $index;
                 $argumentValue->setObjectName($argumentObjectName);
-                if ($argumentValue->getClassName() === null) {
-                    $argumentValue->setClassName('');
-                }
-                $objectConfigurations[$argumentObjectName] = $argument->getValue();
+                $objectConfigurations[$argumentObjectName] = $argumentValue;
                 $argument->set((int)$argument->getIndex(), $argumentObjectName, $argument->getType());
             }
         }
@@ -444,14 +467,13 @@ protected function wireFactoryArguments(array &$objectConfigurations)
      * If mandatory constructor arguments have not been defined yet, this function tries to autowire
      * them if possible.
      *
-     * @param array &$objectConfigurations
+     * @param array<Configuration> &$objectConfigurations
      * @return void
      * @throws UnresolvedDependenciesException
      */
     protected function autowireArguments(array $objectConfigurations): void
     {
         foreach ($objectConfigurations as $objectConfiguration) {
-            /** @var Configuration $objectConfiguration */
             $className = $objectConfiguration->getClassName();
             if ($className === '') {
                 continue;
@@ -464,7 +486,6 @@ protected function autowireArguments(array $objectConfigurations): void
                 continue;
             }
 
-            $className = $objectConfiguration->getClassName();
             if (!$this->reflectionService->hasMethod($className, '__construct')) {
                 continue;
             }
@@ -491,6 +512,9 @@ protected function autowireArguments(array $objectConfigurations): void
                         if ($injectConfigurationAnnotation->type !== ConfigurationManager::CONFIGURATION_TYPE_SETTINGS) {
                             throw new InvalidObjectConfigurationException(sprintf('InjectConfiguration for constructor arguments currently only supports settings. Got type "%s" in constructor argument %s of class %s.', $injectConfigurationAnnotation->type, $index, $className), 1710409120);
                         }
+                        if (!$objectConfiguration->getPackageKey()) {
+                            throw new \Exception('Missing package key');
+                        }
                         $arguments[$index] = new ConfigurationArgument(
                             $index,
                             $injectConfigurationAnnotation->getFullConfigurationPath($objectConfiguration->getPackageKey()),
@@ -505,7 +529,7 @@ protected function autowireArguments(array $objectConfigurations): void
                     } elseif ($parameterInformation['allowsNull'] === true) {
                         $arguments[$index] = new ConfigurationArgument($index, null, ConfigurationArgument::ARGUMENT_TYPES_STRAIGHTVALUE);
                         $arguments[$index]->setAutowiring(Configuration::AUTOWIRING_MODE_OFF);
-                    } elseif (interface_exists($parameterInformation['class'])) {
+                    } elseif (interface_exists($parameterInformation['class'] ?? '')) {
                         $debuggingHint = sprintf('No default implementation for the required interface %s was configured, therefore no specific class name could be used for this dependency. ', $parameterInformation['class']);
                     }
                 }
@@ -522,13 +546,12 @@ protected function autowireArguments(array $objectConfigurations): void
     /**
      * This function tries to find yet unmatched dependencies which need to be injected via "inject*" setter methods.
      *
-     * @param array &$objectConfigurations
+     * @param array<Configuration> &$objectConfigurations
      * @return void
      * @throws ObjectException if an injected property is private
      */
     protected function autowireProperties(array &$objectConfigurations)
     {
-        /** @var Configuration $objectConfiguration */
         foreach ($objectConfigurations as $objectConfiguration) {
             $className = $objectConfiguration->getClassName();
             $properties = $objectConfiguration->getProperties();
@@ -536,6 +559,7 @@ protected function autowireProperties(array &$objectConfigurations)
             if ($className === '') {
                 continue;
             }
+
             if ($objectConfiguration->getAutowiring() === Configuration::AUTOWIRING_MODE_OFF) {
                 continue;
             }
@@ -545,13 +569,6 @@ protected function autowireProperties(array &$objectConfigurations)
             } catch (\TypeError $error) {
                 throw new UnknownClassException(sprintf('The class "%s" defined in the object configuration for object "%s", defined in package: %s, does not exist.', $className, $objectConfiguration->getObjectName(), $objectConfiguration->getPackageKey()), 1352371372);
             }
-            if (!is_array($classMethodNames)) {
-                if (!class_exists($className)) {
-                    throw new UnknownClassException(sprintf('The class "%s" defined in the object configuration for object "%s", defined in package: %s, does not exist.', $className, $objectConfiguration->getObjectName(), $objectConfiguration->getPackageKey()), 1352371371);
-                } else {
-                    throw new UnknownClassException(sprintf('Could not autowire properties of class "%s" because names of methods contained in that class could not be retrieved using get_class_methods().', $className), 1352386418);
-                }
-            }
             foreach ($classMethodNames as $methodName) {
                 if (isset($methodName[6]) && strpos($methodName, 'inject') === 0 && $methodName[6] === strtoupper($methodName[6])) {
                     $propertyName = lcfirst(substr($methodName, 6));
@@ -620,6 +637,9 @@ protected function autowireProperties(array &$objectConfigurations)
                 }
                 /** @var InjectConfiguration $injectConfigurationAnnotation */
                 $injectConfigurationAnnotation = $this->reflectionService->getPropertyAnnotation($className, $propertyName, InjectConfiguration::class);
+                if (!$objectConfiguration->getPackageKey()) {
+                    throw new \Exception('Missing package key', 1744231440);
+                }
                 $properties[$propertyName] = new ConfigurationProperty(
                     $propertyName,
                     [
diff --git a/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationProperty.php b/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationProperty.php
index 75b2b19b60..ad9d39e4fb 100644
--- a/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationProperty.php
+++ b/Neos.Flow/Classes/ObjectManagement/Configuration/ConfigurationProperty.php
@@ -42,7 +42,7 @@ class ConfigurationProperty
 
     /**
      * If specified, this configuration is used for instantiating / retrieving an property of type object
-     * @var Configuration
+     * @var ?Configuration
      */
     protected $objectConfiguration = null;
 
diff --git a/Neos.Flow/Classes/ObjectManagement/DependencyInjection/DependencyProxy.php b/Neos.Flow/Classes/ObjectManagement/DependencyInjection/DependencyProxy.php
index 6c219ba83b..37f05a6fd6 100644
--- a/Neos.Flow/Classes/ObjectManagement/DependencyInjection/DependencyProxy.php
+++ b/Neos.Flow/Classes/ObjectManagement/DependencyInjection/DependencyProxy.php
@@ -32,7 +32,7 @@ class DependencyProxy
     protected $builder;
 
     /**
-     * @var array
+     * @var array<int,mixed>
      */
     protected $propertyVariables = [];
 
@@ -91,7 +91,7 @@ public function _addPropertyVariable(&$propertyVariable)
      * and returns the result of a call to the original method in the dependency
      *
      * @param string $methodName Name of the method to be called
-     * @param array $arguments An array of arguments to be passed to the method
+     * @param array<mixed> $arguments An array of arguments to be passed to the method
      * @return mixed
      */
     public function __call($methodName, array $arguments)
diff --git a/Neos.Flow/Classes/ObjectManagement/DependencyInjection/PropertyInjectionTrait.php b/Neos.Flow/Classes/ObjectManagement/DependencyInjection/PropertyInjectionTrait.php
index 36e0663fc6..02e18a8a50 100644
--- a/Neos.Flow/Classes/ObjectManagement/DependencyInjection/PropertyInjectionTrait.php
+++ b/Neos.Flow/Classes/ObjectManagement/DependencyInjection/PropertyInjectionTrait.php
@@ -13,6 +13,7 @@
 
 /**
  * Boilerplate code for dependency injection
+ * @phpstan-ignore trait.unused (probably API)
  */
 trait PropertyInjectionTrait
 {
diff --git a/Neos.Flow/Classes/ObjectManagement/DependencyInjection/ProxyClassBuilder.php b/Neos.Flow/Classes/ObjectManagement/DependencyInjection/ProxyClassBuilder.php
index 62165d5fcf..d67ab987de 100644
--- a/Neos.Flow/Classes/ObjectManagement/DependencyInjection/ProxyClassBuilder.php
+++ b/Neos.Flow/Classes/ObjectManagement/DependencyInjection/ProxyClassBuilder.php
@@ -35,6 +35,8 @@
 
 /**
  * A Proxy Class Builder which integrates Dependency Injection
+ *
+ * @template ObjectRecordInstance of object
  */
 #[Flow\Scope("singleton")]
 #[Flow\Proxy(false)]
@@ -47,10 +49,14 @@ class ProxyClassBuilder
     protected LoggerInterface $logger;
     protected ConfigurationManager $configurationManager;
     protected CacheManager $cacheManager;
+
+    /**
+     * @phpstan-var CompileTimeObjectManager<ObjectRecordInstance> $objectManager
+     */
     protected CompileTimeObjectManager $objectManager;
 
     /**
-     * @var array<Configuration>
+     * @var array<class-string,Configuration>
      */
     protected array $objectConfigurations = [];
 
@@ -80,6 +86,9 @@ public function injectLogger(LoggerInterface $logger): void
         $this->logger = $logger;
     }
 
+    /**
+     * @phpstan-param CompileTimeObjectManager<ObjectRecordInstance> $objectManager
+     */
     public function injectObjectManager(CompileTimeObjectManager $objectManager): void
     {
         $this->objectManager = $objectManager;
@@ -100,7 +109,8 @@ public function build(): void
 
         foreach ($this->objectConfigurations as $objectName => $objectConfiguration) {
             $className = $objectConfiguration->getClassName();
-            if ($className === ''
+            if (
+                $className === ''
                 || $objectName !== $className
                 || $this->compiler->hasCacheEntryForClass($className) === true
                 || $this->reflectionService->isClassAbstract($className)
@@ -210,6 +220,7 @@ protected function buildSetInstanceCode(Configuration $objectConfiguration): str
      */
     protected function buildSerializeRelatedEntitiesCode(Configuration $objectConfiguration): string
     {
+        /** @var class-string $className (trust me, bro)*/
         $className = $objectConfiguration->getClassName();
 
         if ($this->reflectionService->hasMethod($className, '__sleep')) {
@@ -271,6 +282,7 @@ protected function buildConstructorInjectionCode(Configuration $objectConfigurat
 
         $assignments = [];
         $argumentConfigurations = $objectConfiguration->getArguments();
+        /** @phpstan-ignore argument.type (I guess we excluded "" as class name here already) */
         $constructorParameterInfo = $this->reflectionService->getMethodParameters($objectConfiguration->getClassName(), '__construct');
         $argumentNumberToOptionalInfo = [];
 
@@ -280,9 +292,6 @@ protected function buildConstructorInjectionCode(Configuration $objectConfigurat
 
         $highestArgumentPositionWithAutowiringEnabled = -1;
         foreach ($argumentConfigurations as $argumentNumber => $argumentConfiguration) {
-            if (!$argumentConfiguration instanceof ConfigurationArgument) {
-                continue;
-            }
             $argumentPosition = $argumentNumber - 1;
             if ($argumentConfiguration->getAutowiring() === Configuration::AUTOWIRING_MODE_ON) {
                 $highestArgumentPositionWithAutowiringEnabled = $argumentPosition;
@@ -299,6 +308,7 @@ protected function buildConstructorInjectionCode(Configuration $objectConfigurat
                             $doReturnCode = true;
                             $argumentValueObjectName = $argumentValue->getObjectName();
                             $argumentValueClassName = $argumentValue->getClassName();
+                            /** @phpstan-ignore identical.alwaysFalse (@todo can this even be null?) */
                             if ($argumentValueClassName === null) {
                                 $preparedArgument = $this->buildCustomFactoryCall($argumentValue->getFactoryObjectName(), $argumentValue->getFactoryMethodName(), $argumentValue->getFactoryArguments());
                                 $assignments[$argumentPosition] = $assignmentPrologue . $preparedArgument;
@@ -368,7 +378,6 @@ protected function buildPropertyInjectionCode(Configuration $objectConfiguration
         $commands = [];
         $injectedProperties = [];
         foreach ($objectConfiguration->getProperties() as $propertyName => $propertyConfiguration) {
-            assert($propertyConfiguration instanceof ConfigurationProperty);
             if ($propertyConfiguration->getAutowiring() === Configuration::AUTOWIRING_MODE_OFF) {
                 continue;
             }
@@ -431,7 +440,7 @@ protected function buildPropertyInjectionCode(Configuration $objectConfiguration
      * @param Configuration $objectConfiguration Configuration of the object to inject into
      * @param string $propertyName Name of the property to inject
      * @param Configuration $propertyConfiguration Configuration of the object to inject
-     * @return array lines of PHP code
+     * @return array<string> lines of PHP code
      * @throws UnknownObjectException
      */
     protected function buildPropertyInjectionCodeByConfiguration(Configuration $objectConfiguration, $propertyName, Configuration $propertyConfiguration): array
@@ -439,13 +448,19 @@ protected function buildPropertyInjectionCodeByConfiguration(Configuration $obje
         $className = $objectConfiguration->getClassName();
         $propertyObjectName = $propertyConfiguration->getObjectName();
         $propertyClassName = $propertyConfiguration->getClassName();
+        /** @phpstan-ignore identical.alwaysFalse (@todo can this even be null?) */
         if ($propertyClassName === null) {
-            $preparedSetterArgument = $this->buildCustomFactoryCall($propertyConfiguration->getFactoryObjectName(), $propertyConfiguration->getFactoryMethodName(), $propertyConfiguration->getFactoryArguments());
+            $preparedSetterArgument = $this->buildCustomFactoryCall(
+                $propertyConfiguration->getFactoryObjectName(),
+                $propertyConfiguration->getFactoryMethodName(),
+                $propertyConfiguration->getFactoryArguments()
+            );
         } else {
-            if (!is_string($propertyClassName) || !isset($this->objectConfigurations[$propertyClassName])) {
+            if (!isset($this->objectConfigurations[$propertyClassName])) {
                 $configurationSource = $objectConfiguration->getConfigurationSourceHint();
                 throw new UnknownObjectException('Unknown class "' . $propertyClassName . '", specified as property "' . $propertyName . '" in the object configuration of object "' . $objectConfiguration->getObjectName() . '" (' . $configurationSource . ').', 1296130876);
             }
+
             if ($this->objectConfigurations[$propertyClassName]->getScope() === Configuration::SCOPE_PROTOTYPE) {
                 $preparedSetterArgument = 'new \\' . $propertyClassName . '(' . $this->buildMethodParametersCode($propertyConfiguration->getArguments()) . ')';
             } else {
@@ -453,6 +468,7 @@ protected function buildPropertyInjectionCodeByConfiguration(Configuration $obje
             }
         }
 
+        /** @phpstan-ignore argument.type (I guess we excluded "" as a class name here already) */
         $result = $this->buildSetterInjectionCode($className, $propertyName, $preparedSetterArgument);
         if ($result !== null) {
             return $result;
@@ -468,7 +484,7 @@ protected function buildPropertyInjectionCodeByConfiguration(Configuration $obje
      * @param ConfigurationProperty $propertyConfiguration
      * @param string $propertyName Name of the property to inject
      * @param string $propertyObjectName Object name of the object to inject
-     * @return array lines of PHP code
+     * @return array<string> lines of PHP code
      * @throws UnknownObjectException
      */
     public function buildPropertyInjectionCodeByString(Configuration $objectConfiguration, ConfigurationProperty $propertyConfiguration, $propertyName, $propertyObjectName): array
@@ -491,6 +507,7 @@ public function buildPropertyInjectionCodeByString(Configuration $objectConfigur
             $preparedSetterArgument = '\Neos\Flow\Core\Bootstrap::$staticObjectManager->get(\'' . $propertyObjectName . '\')';
         }
 
+        /** @phpstan-ignore argument.type (I guess we excluded "" as class name here already) */
         $result = $this->buildSetterInjectionCode($className, $propertyName, $preparedSetterArgument);
         if ($result !== null) {
             return $result;
@@ -511,7 +528,7 @@ public function buildPropertyInjectionCodeByString(Configuration $objectConfigur
      * @param string $propertyName Name of the property to inject
      * @param string $configurationType the configuration type of the injected property (one of the ConfigurationManager::CONFIGURATION_TYPE_* constants)
      * @param string|null $configurationPath Path with "." as separator specifying the setting value to inject or NULL if the complete configuration array should be injected
-     * @return array PHP code
+     * @return array<string> PHP code
      */
     public function buildPropertyInjectionCodeByConfigurationTypeAndPath(Configuration $objectConfiguration, $propertyName, $configurationType, $configurationPath = null): array
     {
@@ -522,6 +539,7 @@ public function buildPropertyInjectionCodeByConfigurationTypeAndPath(Configurati
             $preparedSetterArgument = '\Neos\Flow\Core\Bootstrap::$staticObjectManager->get(\Neos\Flow\Configuration\ConfigurationManager::class)->getConfiguration(\'' . $configurationType . '\')';
         }
 
+        /** @phpstan-ignore argument.type (I guess we excluded "" as class name here already) */
         $result = $this->buildSetterInjectionCode($className, $propertyName, $preparedSetterArgument);
         if ($result !== null) {
             return $result;
@@ -535,12 +553,13 @@ public function buildPropertyInjectionCodeByConfigurationTypeAndPath(Configurati
      * @param Configuration $objectConfiguration Configuration of the object to inject into
      * @param string $propertyName Name of the property to inject
      * @param string $cacheIdentifier the identifier of the cache to inject
-     * @return array PHP code
+     * @return array<string> PHP code
      */
     public function buildPropertyInjectionCodeByCacheIdentifier(Configuration $objectConfiguration, string $propertyName, string $cacheIdentifier): array
     {
         $className = $objectConfiguration->getClassName();
         $preparedSetterArgument = '\Neos\Flow\Core\Bootstrap::$staticObjectManager->get(\Neos\Flow\Cache\CacheManager::class)->getCache(\'' . $cacheIdentifier . '\')';
+        /** @phpstan-ignore argument.type (I guess we excluded "" as class name here already) */
         $result = $this->buildSetterInjectionCode($className, $propertyName, $preparedSetterArgument);
         if ($result !== null) {
             return $result;
@@ -555,7 +574,7 @@ public function buildPropertyInjectionCodeByCacheIdentifier(Configuration $objec
      * @param string $propertyClassName Class name of the dependency to inject
      * @param string $propertyName Name of the property in the class to inject into
      * @param string $preparedSetterArgument PHP code to use for retrieving the value to inject
-     * @return array PHP code
+     * @return array<string> PHP code
      */
     protected function buildLazyPropertyInjectionCode($propertyObjectName, $propertyClassName, $propertyName, $preparedSetterArgument): array
     {
@@ -572,7 +591,7 @@ protected function buildLazyPropertyInjectionCode($propertyObjectName, $property
      *
      * If neither inject*() nor set*() exists, but the property does exist, NULL is returned
      *
-     * @param string $className Name of the class to inject into
+     * @param class-string $className Name of the class to inject into
      * @param string $propertyName Name of the property to inject
      * @param string $preparedSetterArgument PHP code to use for retrieving the value to inject
      *
@@ -606,6 +625,7 @@ protected function buildSetterInjectionCode(string $className, string $propertyN
     protected function buildLifecycleInitializationCode(Configuration $objectConfiguration, int $cause): string
     {
         $lifecycleInitializationMethodName = $objectConfiguration->getLifecycleInitializationMethodName();
+        /** @phpstan-ignore argument.type (I guess we excluded "" here already) */
         if (!$this->reflectionService->hasMethod($objectConfiguration->getClassName(), $lifecycleInitializationMethodName)) {
             return '';
         }
@@ -634,6 +654,7 @@ protected function buildLifecycleInitializationCode(Configuration $objectConfigu
     protected function buildLifecycleShutdownCode(Configuration $objectConfiguration, int $cause): string
     {
         $lifecycleShutdownMethodName = $objectConfiguration->getLifecycleShutdownMethodName();
+        /** @phpstan-ignore argument.type (I guess we excluded "" here already) */
         if (!$this->reflectionService->hasMethod($objectConfiguration->getClassName(), $lifecycleShutdownMethodName)) {
             return '';
         }
@@ -656,7 +677,7 @@ protected function buildLifecycleShutdownCode(Configuration $objectConfiguration
     /**
      * FIXME: Not yet completely refactored to new proxy mechanism
      *
-     * @param array $argumentConfigurations
+     * @param array<mixed> $argumentConfigurations
      * @return string
      * @throws InvalidConfigurationTypeException
      */
@@ -703,7 +724,7 @@ protected function buildMethodParametersCode(array $argumentConfigurations): str
     /**
      * @param string $customFactoryObjectName
      * @param string $customFactoryMethodName
-     * @param array $arguments
+     * @param array<mixed> $arguments
      * @return string
      */
     protected function buildCustomFactoryCall($customFactoryObjectName, $customFactoryMethodName, array $arguments): string
@@ -715,7 +736,7 @@ protected function buildCustomFactoryCall($customFactoryObjectName, $customFacto
     /**
      * Compile the result of methods marked with CompileStatic into the proxy class
      *
-     * @param string $className
+     * @param class-string $className
      * @param ProxyClass $proxyClass
      * @return void
      * @throws ObjectException
diff --git a/Neos.Flow/Classes/ObjectManagement/ObjectManager.php b/Neos.Flow/Classes/ObjectManagement/ObjectManager.php
index 6a03f2c458..d76dac75a4 100644
--- a/Neos.Flow/Classes/ObjectManagement/ObjectManager.php
+++ b/Neos.Flow/Classes/ObjectManagement/ObjectManager.php
@@ -25,6 +25,17 @@
 /**
  * Object Manager
  *
+ * @template ObjectRecordInstance of object
+ * @phpstan-type ObjectRecord array{
+ *     i?: ObjectRecordInstance,
+ *     s: int,
+ *     f?: array{0: string, 1: string},
+ *     fa?: array<int,array{t: int, v: mixed}>,
+ *     c: class-string|null,
+ *     p: string,
+ *     l: string|null,
+ * }
+ *
  * @Flow\Scope("singleton")
  * @Flow\Proxy(false)
  */
@@ -50,12 +61,12 @@ class ObjectManager implements ObjectManagerInterface
     /**
      * An array of settings of all packages, indexed by package key
      *
-     * @var array
+     * @var array<string,array<mixed>>
      */
     protected array $allSettings = [];
 
     /**
-     * @var array
+     * @var array<string<ObjectRecordInstance>,ObjectRecord>
      */
     protected array $objects = [];
 
@@ -65,12 +76,12 @@ class ObjectManager implements ObjectManagerInterface
     protected array $dependencyProxies = [];
 
     /**
-     * @var array
+     * @var array<class-string,mixed>
      */
     protected array $classesBeingInstantiated = [];
 
     /**
-     * @var array
+     * @var array<string,string>
      */
     protected array $cachedLowerCasedObjectNames = [];
 
@@ -78,7 +89,7 @@ class ObjectManager implements ObjectManagerInterface
      * A SplObjectStorage containing those objects which need to be shutdown when the container
      * shuts down. Each value of each entry is the respective shutdown method name.
      *
-     * @var \SplObjectStorage
+     * @var \SplObjectStorage<object,mixed>
      */
     protected \SplObjectStorage $shutdownObjects;
 
@@ -86,7 +97,7 @@ class ObjectManager implements ObjectManagerInterface
      * A SplObjectStorage containing only those shutdown objects which have been registered for Flow.
      * These shutdown method will be called after all other shutdown methods have been called.
      *
-     * @var \SplObjectStorage
+     * @var \SplObjectStorage<object,mixed>
      */
     protected \SplObjectStorage $internalShutdownObjects;
 
@@ -105,20 +116,22 @@ public function __construct(ApplicationContext $context)
     /**
      * Sets the objects array
      *
-     * @param array $objects An array of object names and some information about each registered object (scope, lower cased name etc.)
+     * @param array<string<ObjectRecordInstance>,ObjectRecord> $objects An array of object names and some information about each registered object (scope, lower cased name etc.)
      * @return void
      */
     public function setObjects(array $objects): void
     {
         $this->objects = $objects;
+        /** @phpstan-ignore assign.propertyType (classical subtype problem) */
         $this->objects[ObjectManagerInterface::class][self::KEY_INSTANCE] = $this;
+        /** @phpstan-ignore assign.propertyType (classical subtype problem) */
         $this->objects[get_class($this)][self::KEY_INSTANCE] = $this;
     }
 
     /**
      * Injects the global settings array, indexed by package key.
      *
-     * @param array $settings The global settings
+     * @param array<string,mixed> $settings The global settings
      * @return void
      * @Flow\Autowiring(false)
      */
@@ -215,6 +228,7 @@ public function get($objectName, ...$constructorArguments): object
                 return $this->buildObjectByFactory($objectName);
             }
 
+            /** @phpstan-ignore assign.propertyType (classical subtype problem) */
             $this->objects[$objectName][self::KEY_INSTANCE] = $this->buildObjectByFactory($objectName);
             return $this->objects[$objectName][self::KEY_INSTANCE];
         }
@@ -229,6 +243,7 @@ public function get($objectName, ...$constructorArguments): object
             return $this->instantiateClass($className, $constructorArguments);
         }
 
+        /** @phpstan-ignore assign.propertyType (classical subtype problem) */
         $this->objects[$objectName][self::KEY_INSTANCE] = $this->instantiateClass($className, []);
         return $this->objects[$objectName][self::KEY_INSTANCE];
     }
@@ -314,7 +329,7 @@ public function getObjectNameByClassName($className): string|false
      * Returns the implementation class name for the specified object
      *
      * @param string $objectName The object name
-     * @return string|false The class name corresponding to the given object name or false if no such object is registered
+     * @return class-string<object>|false The class name corresponding to the given object name or false if no such object is registered
      * @api
      */
     public function getClassNameByObjectName($objectName): string|false
@@ -322,6 +337,7 @@ public function getClassNameByObjectName($objectName): string|false
         if (!isset($this->objects[$objectName])) {
             return class_exists($objectName) ? $objectName : false;
         }
+        /** @phpstan-ignore return.type (@todo do a class check here) */
         return $this->objects[$objectName][self::KEY_CLASS_NAME] ?? $objectName;
     }
 
@@ -329,7 +345,7 @@ public function getClassNameByObjectName($objectName): string|false
      * Returns the key of the package the specified object is contained in.
      *
      * @param string $objectName The object name
-     * @return string|false The package key or false if no such object exists
+     * @return string|false The package key or false if no such object exists or null if no key was assigned
      * @internal
      */
     public function getPackageKeyByObjectName($objectName): string|false
@@ -361,6 +377,7 @@ public function setInstance($objectName, $instance): void
         if ($this->objects[$objectName][self::KEY_SCOPE] === ObjectConfiguration::SCOPE_PROTOTYPE) {
             throw new Exception\WrongScopeException('Cannot set instance of object "' . $objectName . '" because it is of scope prototype. Only session and singleton instances can be set.', 1265370540);
         }
+        /** @phpstan-ignore assign.propertyType (classical subtype problem) */
         $this->objects[$objectName][self::KEY_INSTANCE] = $instance;
     }
 
@@ -451,7 +468,7 @@ public function forgetInstance($objectName): void
     /**
      * Returns all instances of objects with scope session
      *
-     * @return array
+     * @return array<int,object>
      */
     public function getSessionInstances(): array
     {
@@ -493,7 +510,15 @@ public function shutdown(): void
      * Returns all current object configurations.
      * For internal use in bootstrap only. Can change anytime.
      *
-     * @return array
+     * @return array<string<ObjectRecordInstance>,array{
+     *      i?: ObjectRecordInstance,
+     *      s: int,
+     *      f?: array{0: string, 1: string},
+     *      fa?: array<int,array{t: int, v: mixed}>,
+     *      c: ?class-string,
+     *      p: ?string,
+     *      l: ?string,
+     *  }>
      */
     public function getAllObjectConfigurations(): array
     {
@@ -513,11 +538,12 @@ public function getAllObjectConfigurations(): array
      */
     protected function buildObjectByFactory(string $objectName): object
     {
-        $factory = $this->objects[$objectName][self::KEY_FACTORY][0] ? $this->get($this->objects[$objectName][self::KEY_FACTORY][0]) : null;
-        $factoryMethodName = $this->objects[$objectName][self::KEY_FACTORY][1];
+        $factoryName = $this->objects[$objectName][self::KEY_FACTORY][0] ?? null;
+        $factory = $factoryName ? $this->get($factoryName) : null;
+        $factoryMethodName = $this->objects[$objectName][self::KEY_FACTORY][1] ?? null;
 
         $factoryMethodArguments = [];
-        foreach ($this->objects[$objectName][self::KEY_FACTORY_ARGUMENTS] as $index => $argumentInformation) {
+        foreach ($this->objects[$objectName][self::KEY_FACTORY_ARGUMENTS] ?? [] as $index => $argumentInformation) {
             switch ($argumentInformation[self::KEY_ARGUMENT_TYPE]) {
                 case ObjectConfigurationArgument::ARGUMENT_TYPES_SETTING:
                     $factoryMethodArguments[$index] = $this->get(ConfigurationManager::class)->getConfiguration(ConfigurationManager::CONFIGURATION_TYPE_SETTINGS, $argumentInformation[self::KEY_ARGUMENT_VALUE]);
@@ -535,14 +561,17 @@ protected function buildObjectByFactory(string $objectName): object
             return $factory->$factoryMethodName(...$factoryMethodArguments);
         }
 
+        if (!is_callable($factoryMethodName)) {
+            throw new \Exception($factoryMethodName . ' is not callable', 1744233428);
+        }
         return $factoryMethodName(...$factoryMethodArguments);
     }
 
     /**
      * Speed optimized alternative to ReflectionClass::newInstanceArgs()
      *
-     * @param string $className Name of the class to instantiate
-     * @param array $arguments Arguments to pass to the constructor
+     * @param class-string $className Name of the class to instantiate
+     * @param array<mixed> $arguments Arguments to pass to the constructor
      * @return object The object
      * @throws Exception\CannotBuildObjectException
      * @throws \Exception
@@ -566,7 +595,7 @@ protected function instantiateClass(string $className, array $arguments): object
     /**
      * Executes the methods of the provided objects.
      *
-     * @param \SplObjectStorage $shutdownObjects
+     * @param \SplObjectStorage<object,mixed> $shutdownObjects
      * @return void
      */
     protected function callShutdownMethods(\SplObjectStorage $shutdownObjects): void
diff --git a/Neos.Flow/Classes/ObjectManagement/ObjectManagerInterface.php b/Neos.Flow/Classes/ObjectManagement/ObjectManagerInterface.php
index c3ce693c72..1f9a7bf3c2 100644
--- a/Neos.Flow/Classes/ObjectManagement/ObjectManagerInterface.php
+++ b/Neos.Flow/Classes/ObjectManagement/ObjectManagerInterface.php
@@ -110,7 +110,7 @@ public function getObjectNameByClassName($className);
      * Returns the implementation class name for the specified object
      *
      * @param string $objectName The object name
-     * @return string The class name corresponding to the given object name or false if no such object is registered
+     * @return class-string<object>|false The class name corresponding to the given object name or false if no such object is registered
      * @api
      */
     public function getClassNameByObjectName($objectName);
@@ -119,7 +119,7 @@ public function getClassNameByObjectName($objectName);
      * Returns the key of the package the specified object is contained in.
      *
      * @param string $objectName The object name
-     * @return string The package key or false if no such object exists
+     * @return string|false|null The package key or false if no such object exists or null if no key was assigned
      */
     public function getPackageKeyByObjectName($objectName);
 
@@ -155,7 +155,7 @@ public function forgetInstance($objectName);
     /**
      * Returns all instances of objects with scope session
      *
-     * @return array
+     * @return array<int,object>
      */
     public function getSessionInstances();
 
diff --git a/Neos.Flow/Classes/ObjectManagement/Proxy/Compiler.php b/Neos.Flow/Classes/ObjectManagement/Proxy/Compiler.php
index b54c92cd33..390a47cf9e 100644
--- a/Neos.Flow/Classes/ObjectManagement/Proxy/Compiler.php
+++ b/Neos.Flow/Classes/ObjectManagement/Proxy/Compiler.php
@@ -38,6 +38,7 @@ class Compiler
 
     /**
      * @var CompileTimeObjectManager
+     * @phpstan-ignore missingType.generics (todo: learn how to properly do this)
      */
     protected $objectManager;
 
@@ -52,13 +53,13 @@ class Compiler
     protected $reflectionService;
 
     /**
-     * @var array
+     * @var array<class-string,ProxyClass>
      */
     protected $proxyClasses = [];
 
     /**
      * Hardcoded list of Flow sub packages which must be immune proxying for security, technical or conceptual reasons.
-     * @var array
+     * @var array<int,string>
      */
     protected $excludedSubPackages = ['Neos\Flow\Aop', 'Neos\Flow\Cor', 'Neos\Flow\Obj', 'Neos\Flow\Pac', 'Neos\Flow\Ref', 'Neos\Flow\Uti'];
 
@@ -73,7 +74,7 @@ class Compiler
     /**
      * The final map of proxy classes that end up in the cache.
      *
-     * @var array
+     * @var array<class-string,true>
      */
     protected $storedProxyClasses = [];
 
@@ -86,8 +87,7 @@ public function __construct()
     }
 
     /**
-     * @param CompileTimeObjectManager $objectManager
-     * @return void
+     * @phpstan-ignore missingType.generics (todo: learn how to do this properly)
      */
     public function injectObjectManager(CompileTimeObjectManager $objectManager): void
     {
@@ -128,7 +128,7 @@ public function injectReflectionService(ReflectionService $reflectionService): v
      */
     public function getProxyClass(string $fullClassName): ProxyClass|false
     {
-        if (interface_exists($fullClassName) || (class_exists(BaseTestCase::class) && in_array(BaseTestCase::class, class_parents($fullClassName), true))) {
+        if (interface_exists($fullClassName) || (class_exists(BaseTestCase::class) && in_array(BaseTestCase::class, class_parents($fullClassName) ?: [], true))) {
             return false;
         }
 
@@ -141,7 +141,7 @@ public function getProxyClass(string $fullClassName): ProxyClass|false
             return false;
         }
 
-        if (method_exists($classReflection, 'isEnum') && $classReflection->isEnum()) {
+        if ($classReflection->isEnum()) {
             return false;
         }
 
@@ -153,7 +153,7 @@ public function getProxyClass(string $fullClassName): ProxyClass|false
             return false;
         }
         // Annotation classes (like \Neos\Flow\Annotations\Entity) must never be proxied because that would break the Doctrine AnnotationParser
-        if ($classReflection->isFinal() && preg_match('/^\s?\*\s?\@Annotation\s/m', $classReflection->getDocComment()) === 1) {
+        if ($classReflection->isFinal() && $classReflection->getDocComment() && preg_match('/^\s?\*\s?\@Annotation\s/m', $classReflection->getDocComment()) === 1) {
             return false;
         }
 
@@ -169,7 +169,7 @@ public function getProxyClass(string $fullClassName): ProxyClass|false
      * the proxy class doesn't have to be rebuilt because otherwise the cache would have been flushed by the file
      * monitor or some other mechanism.
      *
-     * @param string $fullClassName Name of the original class
+     * @param class-string $fullClassName Name of the original class
      * @return bool true if a cache entry exists
      */
     public function hasCacheEntryForClass(string $fullClassName): bool
@@ -191,17 +191,22 @@ public function compile(): int
         $compiledClasses = [];
         foreach ($this->objectManager->getRegisteredClassNames() as $fullOriginalClassNames) {
             foreach ($fullOriginalClassNames as $fullOriginalClassName) {
+                /** @var class-string $proxyClassName */
+                $proxyClassName = str_replace('\\', '_', $fullOriginalClassName);
                 if (isset($this->proxyClasses[$fullOriginalClassName])) {
                     $proxyClassCode = $this->proxyClasses[$fullOriginalClassName]->render();
                     if ($proxyClassCode !== '') {
                         $class = new ReflectionClass($fullOriginalClassName);
                         $classPathAndFilename = $class->getFileName();
+                        if ($classPathAndFilename === false) {
+                            throw new \Exception('Missing file name for class', 1744147231);
+                        }
                         $this->cacheOriginalClassFileAndProxyCode($fullOriginalClassName, $classPathAndFilename, $proxyClassCode);
-                        $this->storedProxyClasses[str_replace('\\', '_', $fullOriginalClassName)] = true;
+                        $this->storedProxyClasses[$proxyClassName] = true;
                         $compiledClasses[] = $fullOriginalClassName;
                     }
-                } elseif ($this->classesCache->has(str_replace('\\', '_', $fullOriginalClassName))) {
-                    $this->storedProxyClasses[str_replace('\\', '_', $fullOriginalClassName)] = true;
+                } elseif ($this->classesCache->has($proxyClassName)) {
+                    $this->storedProxyClasses[$proxyClassName] = true;
                 }
             }
         }
@@ -248,6 +253,9 @@ public function getStoredProxyClassMap(): string
     protected function cacheOriginalClassFileAndProxyCode(string $className, string $pathAndFilename, string $proxyClassCode): void
     {
         $classCode = file_get_contents($pathAndFilename);
+        if ($classCode === false) {
+            throw new \Exception('Failed to fetch class code ', 1744147125);
+        }
         $classCode = $this->replaceClassName($classCode, $pathAndFilename);
         $classCode = $this->replaceSelfWithStatic($classCode);
         $classCode = $this->makePrivateConstructorPublic($classCode, $pathAndFilename);
@@ -274,13 +282,18 @@ protected function cacheOriginalClassFileAndProxyCode(string $className, string
      */
     protected function stripOpeningPhpTag(string $classCode): string
     {
-        return preg_replace('/^\s*\\<\\?php(.*\n|.*)/', '$1', $classCode, 1);
+        $result = preg_replace('/^\s*\\<\\?php(.*\n|.*)/', '$1', $classCode, 1);
+        if ($result === null) {
+            throw new \Exception('Invalid PHP code', 1744147081);
+        }
+
+        return $result;
     }
 
 
     /**
      * Render the source (string) form of a PHP Attribute.
-     * @param ReflectionAttribute $attribute
+     * @param ReflectionAttribute<object> $attribute
      * @return string
      */
     public static function renderAttribute(ReflectionAttribute $attribute): string
@@ -343,7 +356,7 @@ public static function renderAnnotation(object $annotation): string
     /**
      * Render an array value as string for an annotation.
      *
-     * @param array $optionValue
+     * @param array<mixed> $optionValue
      * @return string
      */
     protected static function renderOptionArrayValueAsString(array $optionValue): string
@@ -400,6 +413,9 @@ protected function replaceClassName(string $classCode, string $pathAndFilename):
         return str_replace($classCodeUntilClassName, $classCodeUntilClassNameReplacement, $classCode);
     }
 
+    /**
+     * @param array<int,array{0: int, 1: string, 2: int}|string> $tokens
+     */
     private function getClassNameTokenIndex(array $tokens): ?int
     {
         $classToken = null;
diff --git a/Neos.Flow/Classes/ObjectManagement/Proxy/ObjectSerializationTrait.php b/Neos.Flow/Classes/ObjectManagement/Proxy/ObjectSerializationTrait.php
index 06e5607701..228d6f6890 100644
--- a/Neos.Flow/Classes/ObjectManagement/Proxy/ObjectSerializationTrait.php
+++ b/Neos.Flow/Classes/ObjectManagement/Proxy/ObjectSerializationTrait.php
@@ -24,6 +24,7 @@
 
 /**
  * Methods used to serialize objects used by proxy classes.
+ * @phpstan-ignore trait.unused (probably API?)
  */
 trait ObjectSerializationTrait
 {
diff --git a/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyClass.php b/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyClass.php
index d414df4d4d..7052cf3aa3 100644
--- a/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyClass.php
+++ b/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyClass.php
@@ -45,34 +45,38 @@ class ProxyClass
     protected $fullOriginalClassName;
 
     /**
-     * @var ProxyConstructorGenerator
+     * @var ?ProxyConstructorGenerator
      */
     protected $constructor;
 
     /**
-     * @var array
+     * @var array<string,ProxyMethodGenerator>
      */
     protected $methods = [];
 
     /**
-     * @var array
+     * @var array<string,string>
      */
     protected $constants = [];
 
     /**
      * Note: Not using ProxyInterface::class here, since the interface names must have a leading backslash.
      *
-     * @var array
+     * @var array<class-string>
      */
     protected $interfaces = ['\Neos\Flow\ObjectManagement\Proxy\ProxyInterface'];
 
     /**
-     * @var array
+     * @var array<class-string>
      */
     protected $traits = [];
 
     /**
-     * @var array
+     * @var array<string,array{
+     *     initialValueCode: string,
+     *     visibility: string,
+     *     docComment: string,
+     * }>
      */
     protected $properties = [];
 
@@ -88,10 +92,11 @@ class ProxyClass
      */
     public function __construct(string $fullOriginalClassName)
     {
-        if (!str_contains($fullOriginalClassName, '\\')) {
+        $pivot = strrpos($fullOriginalClassName, '\\');
+        if ($pivot === false) {
             $this->originalClassName = $fullOriginalClassName;
         } else {
-            $this->namespace = substr($fullOriginalClassName, 0, strrpos($fullOriginalClassName, '\\'));
+            $this->namespace = substr($fullOriginalClassName, 0, $pivot);
             $this->originalClassName = substr($fullOriginalClassName, strlen($this->namespace) + 1);
         }
         $this->fullOriginalClassName = $fullOriginalClassName;
@@ -186,7 +191,7 @@ public function addProperty(string $name, string $initialValueCode, string $visi
      * Note that the passed interface names must already have a leading backslash,
      * for example "\Neos\Flow\Foo\BarInterface".
      *
-     * @param array $interfaceNames Fully qualified names of the interfaces to introduce
+     * @param array<class-string> $interfaceNames Fully qualified names of the interfaces to introduce
      * @return void
      */
     public function addInterfaces(array $interfaceNames): void
@@ -200,7 +205,7 @@ public function addInterfaces(array $interfaceNames): void
      * Note that the passed trait names must have a leading backslash,
      * for example "\Neos\Flow\ObjectManagement\Proxy\PropertyInjectionTrait".
      *
-     * @param array $traitNames
+     * @param array<class-string> $traitNames
      * @return void
      */
     public function addTraits(array $traitNames): void
@@ -246,7 +251,6 @@ public function render(): string
         }
 
         foreach ($this->methods as $proxyMethod) {
-            assert($proxyMethod instanceof ProxyMethodGenerator);
             if ($proxyMethod->willBeRendered()) {
                 $methodsCode .= PHP_EOL . $proxyMethod->generate();
             }
@@ -274,7 +278,12 @@ protected function buildClassDocumentation(): string
     {
         $classReflection = new ClassReflection($this->fullOriginalClassName);
 
-        $classDocumentation = str_replace("*/", "* @codeCoverageIgnore\n */", $classReflection->getDocComment()) . "\n";
+        $docComment = $classReflection->getDocComment();
+        if (!$docComment) {
+            return '';
+        }
+
+        $classDocumentation = str_replace("*/", "* @codeCoverageIgnore\n */", $docComment) . "\n";
         foreach ($classReflection->getAttributes() as $attribute) {
             $classDocumentation .= Compiler::renderAttribute($attribute) . "\n";
         }
diff --git a/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyConstructorGenerator.php b/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyConstructorGenerator.php
index 4697909129..0963102fdc 100644
--- a/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyConstructorGenerator.php
+++ b/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyConstructorGenerator.php
@@ -18,8 +18,11 @@ final class ProxyConstructorGenerator extends ProxyMethodGenerator
 {
     private ?string $originalVisibility = null;
 
-    /** @phpstan-ignore constructor.unusedParameter */
-    public function __construct($name = null, array $parameters = [], $flags = self::FLAG_PUBLIC, $body = null, $docBlock = null)
+    /**
+     * @param array<mixed> $parameters
+     * @phpstan-ignore constructor.unusedParameter
+     */
+    public function __construct($name = null, array $parameters = [], $flags = self::FLAG_PUBLIC, $body = null, ?DocBlockGenerator $docBlock = null)
     {
         if ($docBlock === null) {
             $docBlock = new DocBlockGenerator();
@@ -46,7 +49,7 @@ public static function fromReflection(\Laminas\Code\Reflection\MethodReflection
         }
         $method->setVisibility(self::VISIBILITY_PUBLIC);
 
-        if (!empty($reflectionMethod->getDocComment())) {
+        if ($reflectionMethod->getDocBlock() !== false) {
             $docBlock = DocBlockGenerator::fromReflection($reflectionMethod->getDocBlock());
             $docBlock->setSourceContent(ProxyClassBuilder::AUTOGENERATED_PROXY_METHOD_COMMENT . PHP_EOL . PHP_EOL . $docBlock->getSourceContent());
         } else {
diff --git a/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyMethodGenerator.php b/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyMethodGenerator.php
index bd501fa412..46d4065c2b 100644
--- a/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyMethodGenerator.php
+++ b/Neos.Flow/Classes/ObjectManagement/Proxy/ProxyMethodGenerator.php
@@ -44,8 +44,9 @@ public static function copyMethodSignatureAndDocblock(\Laminas\Code\Reflection\M
     {
         $instance = parent::copyMethodSignature($reflectionMethod);
         assert($instance instanceof static);
-        if ($reflectionMethod->getDocComment() !== false) {
-            $instance->setDocBlock(DocBlockGenerator::fromReflection($reflectionMethod->getDocBlock()));
+        $docBlock = $reflectionMethod->getDocBlock();
+        if ($docBlock !== false) {
+            $instance->setDocBlock(DocBlockGenerator::fromReflection($docBlock));
         }
         $instance->fullOriginalClassName = $reflectionMethod->getDeclaringClass()->getName();
         $instance->attributesCode = $instance->buildAttributesCode($reflectionMethod);
@@ -271,7 +272,7 @@ protected function buildAttributesCode(\ReflectionMethod $reflectionMethod): str
     /**
      * Formats the arguments of attributes into a string.
      *
-     * @param array $arguments An array of arguments for attributes.
+     * @param array<mixed> $arguments An array of arguments for attributes.
      * @param string $methodName The current method name the proxy code is built for.
      * @return string The formatted arguments as a string.
      * @throws UnsupportedAttributeException
diff --git a/Neos.Flow/Classes/Package.php b/Neos.Flow/Classes/Package.php
index f6ad59cbfb..71f4492289 100644
--- a/Neos.Flow/Classes/Package.php
+++ b/Neos.Flow/Classes/Package.php
@@ -60,7 +60,6 @@ public function boot(Core\Bootstrap $bootstrap)
         if ($context->isTesting()) {
             // TODO: This is technically not necessary as we can register the request handler in the functional bootstrap
             // A future commit will remove this aftter BuildEssentials is adapted
-            /** @phpstan-ignore-next-line composer doesnt autoload this class */
             $bootstrap->registerRequestHandler(new Tests\FunctionalTestRequestHandler($bootstrap));
         }
 
@@ -148,7 +147,6 @@ public function boot(Core\Bootstrap $bootstrap)
             }
         });
 
-        /** @phpstan-ignore-next-line composer doesnt autoload this class */
         $dispatcher->connect(Tests\FunctionalTestCase::class, 'functionalTestTearDown', Mvc\Routing\RouterCachingService::class, 'flushCaches');
 
         $dispatcher->connect(Configuration\ConfigurationManager::class, 'configurationManagerReady', function (Configuration\ConfigurationManager $configurationManager) {
diff --git a/Neos.Flow/Classes/Package/FlowPackageInterface.php b/Neos.Flow/Classes/Package/FlowPackageInterface.php
index fe8586530a..ed254c2ebb 100644
--- a/Neos.Flow/Classes/Package/FlowPackageInterface.php
+++ b/Neos.Flow/Classes/Package/FlowPackageInterface.php
@@ -41,7 +41,7 @@ public function getConfigurationPath();
     /**
      * Returns a generator of filenames of class files provided by functional tests contained in this package
      *
-     * @return \Generator
+     * @return \Generator<class-string,string>
      * @internal
      */
     public function getFunctionalTestsClassFiles();
diff --git a/Neos.Flow/Classes/Package/FlowPackageKey.php b/Neos.Flow/Classes/Package/FlowPackageKey.php
index 5e5a72ec6e..fe23b20851 100644
--- a/Neos.Flow/Classes/Package/FlowPackageKey.php
+++ b/Neos.Flow/Classes/Package/FlowPackageKey.php
@@ -37,7 +37,7 @@ private function __construct(
         }
     }
 
-    public static function fromString(string $value)
+    public static function fromString(string $value): self
     {
         return new self($value);
     }
@@ -63,6 +63,9 @@ public static function isPackageKeyValid(string $string): bool
      * case version of the composer name / namespace will be used, with backslashes replaced by dots.
      *
      * Else the composer name will be used with the slash replaced by a dot
+     *
+     * // @todo replace with ComposerManifest array shape / object from ComposerUtility
+     * @param array<string,mixed> $manifest
      */
     public static function deriveFromManifestOrPath(array $manifest, string $packagePath): self
     {
@@ -77,6 +80,7 @@ public static function deriveFromManifestOrPath(array $manifest, string $package
         $type = $manifest['type'] ?? null;
         if (isset($manifest['autoload']['psr-0']) && is_array($manifest['autoload']['psr-0'])) {
             $namespaces = array_keys($manifest['autoload']['psr-0']);
+            /** @var string $autoloadNamespace */
             $autoloadNamespace = reset($namespaces);
         }
         return self::derivePackageKeyInternal($composerName, $type, $packagePath, $autoloadNamespace);
@@ -110,7 +114,7 @@ private static function derivePackageKeyInternal(string $composerName, ?string $
         }
 
         $packageKey = trim($packageKey, '.');
-        $packageKey = preg_replace('/[^A-Za-z0-9.]/', '', $packageKey);
+        $packageKey = preg_replace('/[^A-Za-z0-9.]/', '', $packageKey) ?: '';
 
         return new self($packageKey);
     }
diff --git a/Neos.Flow/Classes/Package/GenericPackage.php b/Neos.Flow/Classes/Package/GenericPackage.php
index 20d63c4a5d..5cf3e1a4ce 100644
--- a/Neos.Flow/Classes/Package/GenericPackage.php
+++ b/Neos.Flow/Classes/Package/GenericPackage.php
@@ -17,6 +17,12 @@
 
 /**
  * The generic base package that represents third party packages
+ *
+ * @phpstan-type AutoloadConfiguration array{
+ *     namespace: string,
+ *     classPath: string,
+ *     mappingType: string,
+ * }
  */
 class GenericPackage implements PackageInterface, PackageKeyAwareInterface
 {
@@ -54,12 +60,12 @@ class GenericPackage implements PackageInterface, PackageKeyAwareInterface
     protected $autoloadTypes;
 
     /**
-     * @var array
+     * @var array<string,AutoloadConfiguration>
      */
     protected $autoloadConfiguration;
 
     /**
-     * @var array
+     * @var array<int,AutoloadConfiguration>
      */
     protected $flattenedAutoloadConfiguration;
 
@@ -69,7 +75,7 @@ class GenericPackage implements PackageInterface, PackageKeyAwareInterface
      * @param string $packageKey Key of this package
      * @param string $composerName
      * @param string $packagePath Absolute path to the location of the package's composer manifest
-     * @param array $autoloadConfiguration
+     * @param array<string,AutoloadConfiguration> $autoloadConfiguration
      */
     public function __construct($packageKey, $composerName, $packagePath, array $autoloadConfiguration = [])
     {
@@ -82,7 +88,7 @@ public function __construct($packageKey, $composerName, $packagePath, array $aut
     /**
      * Returns the array of filenames of the class files
      *
-     * @return iterable A Generator for class names (key) and their filename, including the absolute path.
+     * @return iterable<class-string,string> A Generator for class names (key) and their filename, including the absolute path.
      */
     public function getClassFiles()
     {
@@ -121,7 +127,7 @@ public function getComposerName()
     /**
      * Returns array of all declared autoload namespaces contained in this package
      *
-     * @return array
+     * @return array<string>
      * @api
      */
     public function getNamespaces()
@@ -157,7 +163,7 @@ public function getPackagePath()
     }
 
     /**
-     * @return array
+     * @return array<string>
      */
     public function getAutoloadPaths()
     {
@@ -169,9 +175,9 @@ public function getAutoloadPaths()
     /**
      * Get the autoload configuration for this package. Any valid composer "autoload" configuration.
      *
-     * @return array
+     * @return array<string,AutoloadConfiguration>
      */
-    public function getAutoloadConfiguration()
+    public function getAutoloadConfiguration(): array
     {
         return $this->autoloadConfiguration;
     }
@@ -179,7 +185,7 @@ public function getAutoloadConfiguration()
     /**
      * Get a flattened array of autoload configurations that have a predictable pattern (PSR-0, PSR-4)
      *
-     * @return array Keys: "namespace", "classPath", "mappingType"
+     * @return array<int,AutoloadConfiguration>
      */
     public function getFlattenedAutoloadConfiguration()
     {
diff --git a/Neos.Flow/Classes/Package/Package.php b/Neos.Flow/Classes/Package/Package.php
index 45a4b47c30..d026d630f2 100644
--- a/Neos.Flow/Classes/Package/Package.php
+++ b/Neos.Flow/Classes/Package/Package.php
@@ -34,7 +34,7 @@ public function boot(Bootstrap $bootstrap)
     /**
      * Returns a generator of filenames of class files provided by functional tests contained in this package
      *
-     * @return \Generator A generator of class names (key) and their filename, including the relative path to the package's directory
+     * @return \Generator<class-string,string> A generator of class names (key) and their filename, including the relative path to the package's directory
      * @internal
      */
     public function getFunctionalTestsClassFiles()
@@ -42,8 +42,12 @@ public function getFunctionalTestsClassFiles()
         $namespaces = $this->getNamespaces();
         if (is_dir($this->packagePath . self::DIRECTORY_TESTS_FUNCTIONAL)) {
             // TODO REFACTOR replace with usage of "autoload-dev"
+            $namespace = reset($namespaces);
+            if (!$namespace) {
+                throw new \Exception('Missing namespace', 1744144110);
+            }
             $namespacePrefix = str_replace('/', '\\', Files::concatenatePaths([
-                reset($namespaces),
+                $namespace,
                 '\\Tests\\Functional\\'
             ]));
             foreach ($this->getClassesInNormalizedAutoloadPath($this->packagePath . FlowPackageInterface::DIRECTORY_TESTS_FUNCTIONAL, $namespacePrefix) as $className => $classPath) {
diff --git a/Neos.Flow/Classes/Package/PackageFactory.php b/Neos.Flow/Classes/Package/PackageFactory.php
index 8f9632e175..d67f720f70 100644
--- a/Neos.Flow/Classes/Package/PackageFactory.php
+++ b/Neos.Flow/Classes/Package/PackageFactory.php
@@ -27,7 +27,7 @@ class PackageFactory
      * @param string $packagePath path to package, relative to base path
      * @param FlowPackageKey $packageKey key / name of the package
      * @param string $composerName
-     * @param array $autoloadConfiguration Autoload configuration as defined in composer.json
+     * @param array<mixed> $autoloadConfiguration Autoload configuration as defined in composer.json
      * @param array{className: class-string<PackageInterface>, pathAndFilename: string}|null $packageClassInformation
      * @return PackageInterface&PackageKeyAwareInterface
      * @throws Exception\CorruptPackageException
@@ -49,9 +49,6 @@ public function create(string $packagesBasePath, string $packagePath, FlowPackag
 
         /** dynamic construction {@see GenericPackage::__construct} */
         $package = new $packageClassName($packageKey->value, $composerName, $absolutePackagePath, $autoloadConfiguration);
-        if (!$package instanceof PackageInterface) {
-            throw new Exception\CorruptPackageException(sprintf('The package class of package "%s" does not implement \Neos\Flow\Package\PackageInterface. Check the file "%s".', $packageKey->value, $packageClassInformation['pathAndFilename']), 1427193370);
-        }
         if (!$package instanceof PackageKeyAwareInterface) {
             throw new Exception\CorruptPackageException(sprintf('The package class of package "%s" does not implement \Neos\Flow\Package\PackageKeyAwareInterface. Check the file "%s".', $packageKey->value, $packageClassInformation['pathAndFilename']), 1711665156);
         }
@@ -100,8 +97,11 @@ public function detectFlowPackageFilePath(FlowPackageKey $packageKey, $absoluteP
         $absolutePackageClassPath = Files::concatenatePaths([$absolutePackagePath, $packageClassPathAndFilename]);
 
         $packageClassContents = file_get_contents($absolutePackageClassPath);
+        if (!$packageClassContents) {
+            throw new \Exception('Could not read package class file', 1744142431);
+        }
         $packageClassName = (new PhpAnalyzer($packageClassContents))->extractFullyQualifiedClassName();
-        if ($packageClassName === null) {
+        if ($packageClassName === null || !is_subclass_of($packageClassName, PackageInterface::class)) {
             throw new Exception\CorruptPackageException(sprintf('The package "%s" does not contain a valid package class. Check if the file "%s" really contains a class.', $packageKey->value, $packageClassPathAndFilename), 1327587091);
         }
 
diff --git a/Neos.Flow/Classes/Package/PackageInterface.php b/Neos.Flow/Classes/Package/PackageInterface.php
index b8ce3e2efd..d08d764258 100644
--- a/Neos.Flow/Classes/Package/PackageInterface.php
+++ b/Neos.Flow/Classes/Package/PackageInterface.php
@@ -25,7 +25,7 @@ interface PackageInterface
     /**
      * Returns the array of filenames of the class files
      *
-     * @return iterable An array or yields the class names (key) and their filename, including the relative path to the package's directory
+     * @return iterable<class-string,string> An array or yields the class names (key) and their filename, including the relative path to the package's directory
      * @api
      */
     public function getClassFiles();
@@ -41,7 +41,7 @@ public function getComposerName();
     /**
      * Returns an array of all namespaces declared for this package.
      *
-     * @return array
+     * @return array<string>
      * @api
      */
     public function getNamespaces();
diff --git a/Neos.Flow/Classes/Package/PackageManager.php b/Neos.Flow/Classes/Package/PackageManager.php
index d2b0522118..fdea0ef576 100644
--- a/Neos.Flow/Classes/Package/PackageManager.php
+++ b/Neos.Flow/Classes/Package/PackageManager.php
@@ -27,6 +27,13 @@
 /**
  * The default Flow Package Manager
  *
+ * @phpstan-type ComposerManifest array{
+ *     require?: array<string>,
+ *     extra?: array{neos?: array{loading-order?: array{after?: mixed}}},
+ *     autoload?: array<string,array<string,string>>,
+ *     name: string,
+ * }
+ *
  * @api
  * @Flow\Scope("singleton")
  */
@@ -60,7 +67,7 @@ class PackageManager
     /**
      * Array of available packages, indexed by package key (case sensitive)
      *
-     * @var array
+     * @var array<string,PackageInterface&PackageKeyAwareInterface>
      */
     protected $packages = [];
 
@@ -74,7 +81,7 @@ class PackageManager
     /**
      * A map between ComposerName and PackageKey, only available when scanAvailablePackages is run
      *
-     * @var array
+     * @var array<string,string>
      */
     protected $composerNameToPackageKeyMap = [];
 
@@ -93,12 +100,12 @@ class PackageManager
     /**
      * Package states configuration as stored in the PackageStates.php file
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $packageStatesConfiguration = [];
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $settings;
 
@@ -111,7 +118,7 @@ class PackageManager
      * Inject settings into the package manager. Has to be called explicitly on object initialization as
      * the package manager subpackage is excluded from proxy class building.
      *
-     * @param array $settings
+     * @param array<string,mixed> $settings
      * @return void
      */
     public function injectSettings(array $settings): void
@@ -145,8 +152,6 @@ public function initialize(Bootstrap $bootstrap): void
         $this->bootstrap = $bootstrap;
         $this->packageStatesConfiguration = $this->getCurrentPackageStates();
         $this->registerPackagesFromConfiguration($this->packageStatesConfiguration);
-        /** @var PackageInterface $package */
-
         foreach ($this->packages as $package) {
             if ($package instanceof FlowPackageInterface) {
                 $this->flowPackages[$package->getPackageKey()] = $package;
@@ -197,11 +202,11 @@ public function getPackagesBasePath(): string
      * Returns a PackageInterface object for the specified package.
      *
      * @param string $packageKey
-     * @return PackageInterface The requested package object
+     * @return PackageInterface&PackageKeyAwareInterface The requested package object
      * @throws Exception\UnknownPackageException if the specified package is not known
      * @api
      */
-    public function getPackage($packageKey): PackageInterface
+    public function getPackage($packageKey): PackageInterface&PackageKeyAwareInterface
     {
         if (!$this->isPackageAvailable($packageKey)) {
             throw new Exception\UnknownPackageException('Package "' . $packageKey . '" is not available. Please check if the package exists and that the package key is correct (package keys are case sensitive).', 1166546734);
@@ -214,7 +219,7 @@ public function getPackage($packageKey): PackageInterface
      * Returns an array of PackageInterface objects of all available packages.
      * A package is available, if the package directory contains valid meta information.
      *
-     * @return array<PackageInterface>
+     * @return array<PackageInterface&PackageKeyAwareInterface>
      * @api
      */
     public function getAvailablePackages(): array
@@ -229,7 +234,7 @@ public function getAvailablePackages(): array
      * @param string $packageState defaults to available
      * @param string $packageType
      *
-     * @return array<PackageInterface>
+     * @return array<PackageInterface&PackageKeyAwareInterface>
      * @throws Exception\InvalidPackageStateException
      * @api
      */
@@ -256,9 +261,9 @@ public function getFilteredPackages($packageState = 'available', $packageType =
      * Returns an array of PackageInterface objects in the given array of packages
      * that are of the specified package type.
      *
-     * @param array $packages Array of PackageInterface objects to be filtered
+     * @param array<PackageInterface&PackageKeyAwareInterface> $packages Array of PackageInterface objects to be filtered
      * @param string $packageType Filter out anything that's not of this packageType
-     * @return array<PackageInterface>
+     * @return array<PackageInterface&PackageKeyAwareInterface>
      */
     protected function filterPackagesByType($packages, $packageType): array
     {
@@ -276,7 +281,7 @@ protected function filterPackagesByType($packages, $packageType): array
      * Create a package, given the package key
      *
      * @param string $packageKey The package key of the new package
-     * @param array $manifest A composer manifest as associative array.
+     * @param array<string,mixed> $manifest A composer manifest as associative array.
      * @param string $packagesPath If specified, the package will be created in this path, otherwise the default "Application" directory is used
      * @return PackageInterface The newly created package
      *
@@ -371,7 +376,7 @@ public function createPackage($packageKey, array $manifest = [], $packagesPath =
     /**
      * Rescans available packages, order and write a new PackageStates file.
      *
-     * @return array The found and sorted package states.
+     * @return array<mixed> The found and sorted package states.
      * @throws Exception
      * @throws InvalidConfigurationException
      * @throws FilesException
@@ -389,7 +394,7 @@ public function rescanPackages(): array
      * initialises a package scan if the file was not found or the configuration format
      * was not current.
      *
-     * @return array
+     * @return array<mixed>
      * @throws Exception
      * @throws InvalidConfigurationException
      * @throws FilesException
@@ -417,7 +422,7 @@ protected function getCurrentPackageStates(): array
     /**
      * Load the current package states
      *
-     * @return array
+     * @return array<mixed>
      */
     protected function loadPackageStates(): array
     {
@@ -428,7 +433,7 @@ protected function loadPackageStates(): array
      * Scans all directories in the packages directories for available packages.
      * For each package a Package object is created and stored in $this->packages.
      *
-     * @return array
+     * @return array<string,mixed>
      * @throws Exception
      * @throws InvalidConfigurationException
      */
@@ -483,6 +488,8 @@ protected function scanAvailablePackages(): array
     /**
      * Traverses directories recursively from the given starting point and yields folder paths, who contain a composer.json.
      * When a composer.json was found, traversing into lower directories is stopped.
+     *
+     * @implements \Generator<string>
      */
     protected function findComposerPackagesInPath(string $startingDirectory): \Generator
     {
@@ -508,6 +515,14 @@ protected function findComposerPackagesInPath(string $startingDirectory): \Gener
     /**
      * @throws Exception\CorruptPackageException
      * @throws Exception\InvalidPackagePathException
+     * @param ComposerManifest $composerManifest
+     * @return array{
+     *     packageKey: string,
+     *     packagePath: string,
+     *     composerName: string,
+     *     autoloadConfiguration: array<mixed>,
+     *     packageClassInformation: array<string>,
+     * }
      */
     protected function preparePackageStateConfiguration(FlowPackageKey $packageKey, string $packagePath, array $composerManifest): array
     {
@@ -525,7 +540,7 @@ protected function preparePackageStateConfiguration(FlowPackageKey $packageKey,
     /**
      * Requires and registers all packages which were defined in packageStatesConfiguration
      *
-     * @param array $packageStatesConfiguration
+     * @param array<string,mixed> $packageStatesConfiguration
      * @throws Exception\CorruptPackageException
      */
     protected function registerPackagesFromConfiguration($packageStatesConfiguration): void
@@ -541,7 +556,7 @@ protected function registerPackagesFromConfiguration($packageStatesConfiguration
      * to all relevant data arrays.
      *
      * @param string $composerName
-     * @param array $packageStateConfiguration
+     * @param array<string,mixed> $packageStateConfiguration
      * @return void
      * @throws Exception\CorruptPackageException
      */
@@ -558,8 +573,8 @@ protected function registerPackageFromStateConfiguration($composerName, $package
      * Takes the given packageStatesConfiguration, sorts it by dependencies, saves it and returns
      * the ordered list
      *
-     * @param array $packageStates
-     * @return array
+     * @param array<string,mixed> $packageStates
+     * @return array<string,mixed>
      * @throws Exception\PackageStatesFileNotWritableException
      * @throws FilesException
      */
@@ -574,7 +589,7 @@ protected function sortAndSavePackageStates(array $packageStates): array
     /**
      * Save the given (ordered) array of package states data
      *
-     * @param array $orderedPackageStates
+     * @param array<string,mixed> $orderedPackageStates
      * @throws Exception\PackageStatesFileNotWritableException
      * @throws FilesException
      */
@@ -620,12 +635,15 @@ protected function savePackageStates(array $orderedPackageStates): void
      * and package configurations arrays holds all packages in the correct
      * initialization order.
      *
-     * @param array $packageStates The unordered package states
-     * @return array ordered package states.
+     * @param array<string,mixed> $packageStates The unordered package states
+     * @return array<string,mixed> ordered package states.
      */
     protected function sortAvailablePackagesByDependencies(array $packageStates): array
     {
-        $packageOrderResolver = new PackageOrderResolver($packageStates['packages'], $this->collectPackageManifestData($packageStates));
+        $packageOrderResolver = new PackageOrderResolver(
+            $packageStates['packages'],
+            $this->collectPackageManifestData($packageStates)
+        );
         $packageStates['packages'] = $packageOrderResolver->sort();
 
         return $packageStates;
@@ -634,8 +652,8 @@ protected function sortAvailablePackagesByDependencies(array $packageStates): ar
     /**
      * Collects the manifest data for all packages in the given package states array
      *
-     * @param array $packageStates
-     * @return array
+     * @param array<string,mixed> $packageStates
+     * @return array<string,ComposerManifest>
      */
     protected function collectPackageManifestData(array $packageStates): array
     {
diff --git a/Neos.Flow/Classes/Package/PackageOrderResolver.php b/Neos.Flow/Classes/Package/PackageOrderResolver.php
index 8fae9f6b99..c1f9235be8 100644
--- a/Neos.Flow/Classes/Package/PackageOrderResolver.php
+++ b/Neos.Flow/Classes/Package/PackageOrderResolver.php
@@ -3,21 +3,23 @@
 
 /**
  * A simple package dependency order solver. Just sorts by simple dependencies, does no checking or versions.
+ *
+ * @phpstan-import-type ComposerManifest from PackageManager
  */
 class PackageOrderResolver
 {
     /**
-     * @var array
+     * @var array<string,ComposerManifest>
      */
     protected $manifestData;
 
     /**
-     * @var array
+     * @var array<string,array<string,mixed>>
      */
     protected $packageStates;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $sortedPackages;
 
@@ -25,13 +27,13 @@ class PackageOrderResolver
      * Array with state information of still unsorted packages.
      * The key is a package key, the value is "-1" if it is on stack for cycle detection; otherwise it is the number of times it was attempted to sort it already.
      *
-     * @var array
+     * @var array<string,int>
      */
     protected $unsortedPackages;
 
     /**
-     * @param array $packages The array of package states to order by dependencies
-     * @param array $manifestData The manifests of all given packages for reading dependencies
+     * @param array<string,array<string,mixed>> $packages The array of package states to order by dependencies
+     * @param array<string,ComposerManifest> $manifestData The manifests of all given packages for reading dependencies
      */
     public function __construct(array $packages, array $manifestData)
     {
@@ -43,7 +45,7 @@ public function __construct(array $packages, array $manifestData)
     /**
      * Sorts the packages and returns the sorted packages array
      *
-     * @return array
+     * @return array<mixed>
      */
     public function sort()
     {
@@ -100,7 +102,6 @@ protected function sortPackage($packageKey)
             $unresolvedDependencies += $this->sortListBefore($packageKey, $sortingConfiguration);
         }
 
-        /** @var array $packageState */
         $packageState = $this->packageStates[$packageKey];
         $this->unsortedPackages[$packageKey] = $iterationForPackage + 1;
         if ($unresolvedDependencies === 0) {
diff --git a/Neos.Flow/Classes/Persistence/AbstractPersistenceManager.php b/Neos.Flow/Classes/Persistence/AbstractPersistenceManager.php
index 2db99302da..c887f1fc75 100644
--- a/Neos.Flow/Classes/Persistence/AbstractPersistenceManager.php
+++ b/Neos.Flow/Classes/Persistence/AbstractPersistenceManager.php
@@ -22,12 +22,12 @@
 abstract class AbstractPersistenceManager implements PersistenceManagerInterface
 {
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $settings = [];
 
     /**
-     * @var array
+     * @var array<string,Aspect\PersistenceMagicInterface>
      */
     protected $newObjects = [];
 
@@ -46,7 +46,7 @@ abstract class AbstractPersistenceManager implements PersistenceManagerInterface
      * Injects the Flow settings, the persistence part is kept
      * for further use.
      *
-     * @param array $settings
+     * @param array<string,array<mixed>> $settings
      * @return void
      */
     public function injectSettings(array $settings): void
diff --git a/Neos.Flow/Classes/Persistence/AllowedObjectsContainer.php b/Neos.Flow/Classes/Persistence/AllowedObjectsContainer.php
index a013cec08e..c877ce1960 100644
--- a/Neos.Flow/Classes/Persistence/AllowedObjectsContainer.php
+++ b/Neos.Flow/Classes/Persistence/AllowedObjectsContainer.php
@@ -18,6 +18,7 @@
 /**
  * A container for the list of allowed objects to be persisted during this request.
  *
+ * @extends \SplObjectStorage<object,mixed>
  * @Flow\Scope("singleton")
  */
 final class AllowedObjectsContainer extends \SplObjectStorage
diff --git a/Neos.Flow/Classes/Persistence/Aspect/EmbeddedValueObjectPointcutFilter.php b/Neos.Flow/Classes/Persistence/Aspect/EmbeddedValueObjectPointcutFilter.php
index e4526c1003..359e31a0a2 100644
--- a/Neos.Flow/Classes/Persistence/Aspect/EmbeddedValueObjectPointcutFilter.php
+++ b/Neos.Flow/Classes/Persistence/Aspect/EmbeddedValueObjectPointcutFilter.php
@@ -39,7 +39,7 @@ public function injectReflectionService(\Neos\Flow\Reflection\ReflectionService
     /**
      * Checks if the specified class and method matches against the filter
      *
-     * @param string $className Name of the class to check against
+     * @param class-string $className Name of the class to check against
      * @param string $methodName Name of the method to check against
      * @param string $methodDeclaringClassName Name of the class the method was originally declared in
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
@@ -64,7 +64,7 @@ public function hasRuntimeEvaluationsDefinition()
     /**
      * Returns runtime evaluations for a previously matched pointcut
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition()
     {
diff --git a/Neos.Flow/Classes/Persistence/Aspect/PersistenceMagicAspect.php b/Neos.Flow/Classes/Persistence/Aspect/PersistenceMagicAspect.php
index 7daf1e95dc..46b8d4e506 100644
--- a/Neos.Flow/Classes/Persistence/Aspect/PersistenceMagicAspect.php
+++ b/Neos.Flow/Classes/Persistence/Aspect/PersistenceMagicAspect.php
@@ -49,21 +49,21 @@ class PersistenceMagicAspect
     /**
      * @Flow\Pointcut("classAnnotatedWith(Neos\Flow\Annotations\Entity) || classAnnotatedWith(Doctrine\ORM\Mapping\Entity)")
      */
-    public function isEntity()
+    public function isEntity(): void
     {
     }
 
     /**
      * @Flow\Pointcut("classAnnotatedWith(Neos\Flow\Annotations\ValueObject) && !filter(Neos\Flow\Persistence\Aspect\EmbeddedValueObjectPointcutFilter)")
      */
-    public function isNonEmbeddedValueObject()
+    public function isNonEmbeddedValueObject(): void
     {
     }
 
     /**
      * @Flow\Pointcut("Neos\Flow\Persistence\Aspect\PersistenceMagicAspect->isEntity || Neos\Flow\Persistence\Aspect\PersistenceMagicAspect->isNonEmbeddedValueObject")
      */
-    public function isEntityOrValueObject()
+    public function isEntityOrValueObject(): void
     {
     }
 
@@ -114,6 +114,9 @@ public function generateValueHash(JoinPointInterface $joinPoint)
         $hashSourceParts = [];
 
         $classSchema = $this->reflectionService->getClassSchema($proxyClassName);
+        if (!$classSchema) {
+            throw new \Exception('Missing class schema for proxy class ' . $proxyClassName);
+        }
         foreach ($classSchema->getProperties() as $property => $propertySchema) {
             // Currently, private properties are transient. Should this behaviour change, they need to be included
             // in the value hash generation
@@ -138,6 +141,6 @@ public function generateValueHash(JoinPointInterface $joinPoint)
         $serializedSource = ($this->useIgBinary === true) ? igbinary_serialize($hashSourceParts) : serialize($hashSourceParts);
 
         $proxy = $joinPoint->getProxy();
-        ObjectAccess::setProperty($proxy, 'Persistence_Object_Identifier', sha1($serializedSource), true);
+        ObjectAccess::setProperty($proxy, 'Persistence_Object_Identifier', sha1($serializedSource ?: ''), true);
     }
 }
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/ArrayTypeConverter.php b/Neos.Flow/Classes/Persistence/Doctrine/ArrayTypeConverter.php
index 46bdd4ae3c..0a2de45843 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/ArrayTypeConverter.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/ArrayTypeConverter.php
@@ -63,16 +63,15 @@ class ArrayTypeConverter extends AbstractTypeConverter
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
-     * @param PropertyMappingConfigurationInterface $configuration
-     * @return mixed|Error the target type, or an error object if a user-error occurred
+     * @param array<string,mixed> $convertedChildProperties
+     * @return array<mixed> the target type, or an error object if a user-error occurred
      * @throws TypeConverterException thrown in case a developer error occurred
      * @api
      */
     public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
         $result = [];
-        $convertElements = $configuration->getConfigurationValue(ArrayTypeConverter::class, self::CONFIGURATION_CONVERT_ELEMENTS);
+        $convertElements = $configuration?->getConfigurationValue(ArrayTypeConverter::class, self::CONFIGURATION_CONVERT_ELEMENTS) ?: true;
         foreach ($source as $element) {
             if ($convertElements === true) {
                 $element = $this->propertyMapper->convert($element, 'array', $configuration);
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/CountWalker.php b/Neos.Flow/Classes/Persistence/Doctrine/CountWalker.php
index c1695d1b3a..f98cfeb319 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/CountWalker.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/CountWalker.php
@@ -34,7 +34,7 @@ public function walkSelectStatement(SelectStatement $AST)
         $parent = null;
         $parentName = null;
         foreach ($this->getQueryComponents() as $dqlAlias => $qComp) {
-            if ($qComp['parent'] === null && $qComp['nestingLevel'] === 0) {
+            if (($qComp['parent'] ?? null) === null && $qComp['nestingLevel'] === 0) {
                 $parent = $qComp;
                 $parentName = $dqlAlias;
                 break;
@@ -45,10 +45,13 @@ public function walkSelectStatement(SelectStatement $AST)
             $AST->selectClause->isDistinct = true;
         }
 
+        if (!is_string($parentName)) {
+            throw new \Exception('Missing parent name', 1744138349);
+        }
         $pathExpression = new PathExpression(
             PathExpression::TYPE_STATE_FIELD | PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION,
             $parentName,
-            $parent['metadata']->getSingleIdentifierFieldName()
+            ($parent['metadata'] ?? null)?->getSingleIdentifierFieldName()
         );
         $pathExpression->type = PathExpression::TYPE_STATE_FIELD;
 
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/DataTypes/JsonArrayType.php b/Neos.Flow/Classes/Persistence/Doctrine/DataTypes/JsonArrayType.php
index 33f829684a..0be649ad1f 100755
--- a/Neos.Flow/Classes/Persistence/Doctrine/DataTypes/JsonArrayType.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/DataTypes/JsonArrayType.php
@@ -60,7 +60,7 @@ public function getMappedDatabaseTypes(AbstractPlatform $platform): array
      *
      * @param mixed $value The value to convert.
      * @param AbstractPlatform $platform The currently used database platform.
-     * @return array|null The PHP representation of the value.
+     * @return array<mixed>|null The PHP representation of the value.
      * @throws ConversionException
      * @throws TypeConverterException
      */
@@ -114,6 +114,9 @@ public function convertToDatabaseValue($value, AbstractPlatform $platform): ?str
      */
     protected function initializeDependencies(): void
     {
+        if (!Bootstrap::$staticObjectManager) {
+            throw new \Exception('Cannot initialize dependencies without the static object manager', 1744398442);
+        }
         if ($this->persistenceManager === null) {
             $this->persistenceManager = Bootstrap::$staticObjectManager->get(PersistenceManagerInterface::class);
             $this->reflectionService = Bootstrap::$staticObjectManager->get(ReflectionService::class);
@@ -124,11 +127,15 @@ protected function initializeDependencies(): void
      * Traverses the $array and replaces known persisted objects (tuples of
      * type and identifier) with actual instances.
      *
+     * @param array<mixed> $array
      * @throws TypeConverterException
      */
     protected function decodeObjectReferences(array &$array): void
     {
-        assert($this->persistenceManager instanceof PersistenceManagerInterface);
+        $persistenceManager = $this->persistenceManager;
+        if (!$persistenceManager) {
+            throw new \Exception('PersistenceManager is missing', 1744138182);
+        }
 
         foreach ($array as &$value) {
             if (!is_array($value)) {
@@ -138,7 +145,7 @@ protected function decodeObjectReferences(array &$array): void
             if (isset($value['__value_object_value'], $value['__value_object_type'])) {
                 $value = self::deserializeValueObject($value);
             } elseif (isset($value['__flow_object_type'])) {
-                $value = $this->persistenceManager->getObjectByIdentifier($value['__identifier'], $value['__flow_object_type'], true);
+                $value = $persistenceManager->getObjectByIdentifier($value['__identifier'], $value['__flow_object_type'], true);
             } else {
                 $this->decodeObjectReferences($value);
             }
@@ -146,6 +153,7 @@ protected function decodeObjectReferences(array &$array): void
     }
 
     /**
+     * @param array<string,mixed> $serializedValueObject
      * @throws \InvalidArgumentException
      * @throws TypeConverterException
      */
@@ -168,12 +176,16 @@ public static function deserializeValueObject(array $serializedValueObject): \Js
      * Traverses the $array and replaces known persisted objects with a tuple of
      * type and identifier.
      *
+     * @param array<mixed> $array
      * @throws \RuntimeException
      * @throws \JsonException
      */
     protected function encodeObjectReferences(array &$array): void
     {
-        assert($this->persistenceManager instanceof PersistenceManagerInterface);
+        $persistenceManager = $this->persistenceManager;
+        if (!$persistenceManager) {
+            throw new \Exception('PersistenceManager is missing', 1744138137);
+        }
 
         foreach ($array as &$value) {
             if (is_array($value)) {
@@ -197,7 +209,7 @@ protected function encodeObjectReferences(array &$array): void
                 throw new \RuntimeException('Collection in array properties is not supported', 1375196581);
             } elseif ($value instanceof \ArrayObject) {
                 throw new \RuntimeException('ArrayObject in array properties is not supported', 1375196582);
-            } elseif ($this->persistenceManager->isNewObject($value) === false
+            } elseif ($persistenceManager->isNewObject($value) === false
                 && (
                     $this->reflectionService->isClassAnnotatedWith($propertyClassName, Flow\Entity::class)
                     || $this->reflectionService->isClassAnnotatedWith($propertyClassName, Flow\ValueObject::class)
@@ -206,7 +218,7 @@ protected function encodeObjectReferences(array &$array): void
             ) {
                 $value = [
                     '__flow_object_type' => $propertyClassName,
-                    '__identifier' => $this->persistenceManager->getIdentifierByObject($value)
+                    '__identifier' => $persistenceManager->getIdentifierByObject($value)
                 ];
             } elseif ($value instanceof \JsonSerializable
                 && DenormalizingObjectConverter::isDenormalizable(get_class($value))
@@ -219,6 +231,7 @@ protected function encodeObjectReferences(array &$array): void
     /**
      * @throws \RuntimeException
      * @throws \JsonException
+     * @return array<string,mixed>
      */
     public static function serializeValueObject(\JsonSerializable $valueObject): array
     {
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/EntityManagerConfiguration.php b/Neos.Flow/Classes/Persistence/Doctrine/EntityManagerConfiguration.php
index 93e19e6942..3225e80660 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/EntityManagerConfiguration.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/EntityManagerConfiguration.php
@@ -99,7 +99,7 @@ public function configureEntityManager(Connection $connection, Configuration $co
     }
 
     /**
-     * @param array $configuredSubscribers
+     * @param array<class-string> $configuredSubscribers
      * @param EventManager $eventManager
      * @throws IllegalObjectTypeException
      */
@@ -115,7 +115,7 @@ protected function registerEventSubscribers(array $configuredSubscribers, EventM
     }
 
     /**
-     * @param array $configuredListeners
+     * @param array<array{listener: class-string<object>, events: string|array<string>}> $configuredListeners
      * @param EventManager $eventManager
      */
     protected function registerEventListeners(array $configuredListeners, EventManager $eventManager): void
@@ -130,7 +130,7 @@ protected function registerEventListeners(array $configuredListeners, EventManag
      * Apply configured settings regarding DQL to the Doctrine Configuration.
      * At the moment, these are custom DQL functions.
      *
-     * @param array $configuredSettings
+     * @param array<string,mixed> $configuredSettings
      * @param Configuration $doctrineConfiguration
      * @return void
      */
@@ -174,7 +174,7 @@ protected function applyCacheConfiguration(Configuration $config): void
     /**
      * Apply configured settings regarding Doctrine's second level cache.
      *
-     * @param array $configuredSettings
+     * @param array<string,mixed> $configuredSettings
      * @param Configuration $doctrineConfiguration
      * @return void
      * @throws NoSuchCacheException
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/EntityManagerFactory.php b/Neos.Flow/Classes/Persistence/Doctrine/EntityManagerFactory.php
index 6380139d5e..3fc9c34544 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/EntityManagerFactory.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/EntityManagerFactory.php
@@ -55,7 +55,7 @@ class EntityManagerFactory
     protected $environment;
 
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $settings = [];
 
@@ -63,7 +63,7 @@ class EntityManagerFactory
      * Injects the Flow settings, the persistence part is kept
      * for further use.
      *
-     * @param array $settings
+     * @param array<string,array<string,mixed>> $settings
      * @return void
      * @throws InvalidConfigurationException
      */
@@ -138,7 +138,7 @@ public function create()
      * @param EventManager $eventManager
      * @Flow\Signal
      */
-    public function emitBeforeDoctrineEntityManagerCreation(Connection $connection, Configuration $config, EventManager $eventManager)
+    public function emitBeforeDoctrineEntityManagerCreation(Connection $connection, Configuration $config, EventManager $eventManager): void
     {
     }
 
@@ -147,7 +147,7 @@ public function emitBeforeDoctrineEntityManagerCreation(Connection $connection,
      * @param EntityManager $entityManager
      * @Flow\Signal
      */
-    public function emitAfterDoctrineEntityManagerCreation(Configuration $config, EntityManager $entityManager)
+    public function emitAfterDoctrineEntityManagerCreation(Configuration $config, EntityManager $entityManager): void
     {
     }
 
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/Mapping/ClassMetadata.php b/Neos.Flow/Classes/Persistence/Doctrine/Mapping/ClassMetadata.php
index 4a9fc7c8dc..5e24fd0d14 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/Mapping/ClassMetadata.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/Mapping/ClassMetadata.php
@@ -17,6 +17,8 @@
 /**
  * A ClassMetadata instance holds all the object-relational mapping metadata
  * of an entity and it's associations.
+ *
+ * @extends \Doctrine\ORM\Mapping\ClassMetadata<object>
  */
 class ClassMetadata extends \Doctrine\ORM\Mapping\ClassMetadata
 {
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/Mapping/ClassMetadataFactory.php b/Neos.Flow/Classes/Persistence/Doctrine/Mapping/ClassMetadataFactory.php
index eecf79fab8..ee630624e4 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/Mapping/ClassMetadataFactory.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/Mapping/ClassMetadataFactory.php
@@ -21,7 +21,7 @@ class ClassMetadataFactory extends \Doctrine\ORM\Mapping\ClassMetadataFactory
     /**
      * Creates a new ClassMetadata instance for the given class name.
      *
-     * @param string $className
+     * @param class-string $className
      * @return ClassMetadata
      */
     protected function newClassMetadataInstance($className)
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/Mapping/Driver/FlowAnnotationDriver.php b/Neos.Flow/Classes/Persistence/Doctrine/Mapping/Driver/FlowAnnotationDriver.php
index 8539422da6..d9fe31846a 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/Mapping/Driver/FlowAnnotationDriver.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/Mapping/Driver/FlowAnnotationDriver.php
@@ -70,7 +70,7 @@ class FlowAnnotationDriver implements DoctrineMappingDriverInterface, PointcutFi
     protected $entityManager;
 
     /**
-     * @var array
+     * @var ?array<int,class-string>
      */
     protected $classNames;
 
@@ -109,7 +109,7 @@ public function setEntityManager(EntityManagerInterface $entityManager)
     /**
      * Fetch a class schema for the given class, if possible.
      *
-     * @param string $className
+     * @param class-string $className
      * @return ClassSchema
      * @throws ClassSchemaNotFoundException
      */
@@ -126,7 +126,7 @@ protected function getClassSchema($className)
     /**
      * Check for $className being an aggregate root.
      *
-     * @param string $className
+     * @param class-string $className
      * @param string $propertySourceHint
      * @return boolean
      * @throws ClassSchemaNotFoundException
@@ -146,7 +146,7 @@ protected function isAggregateRoot($className, $propertySourceHint)
     /**
      * Check for $className being a value object.
      *
-     * @param string $className
+     * @param class-string $className
      * @param string $propertySourceHint
      * @return boolean
      * @throws ClassSchemaNotFoundException
@@ -166,8 +166,8 @@ protected function isValueObject($className, $propertySourceHint)
     /**
      * Loads the metadata for the specified class into the provided container.
      *
-     * @param string $className
-     * @param ClassMetadata $metadata
+     * @param class-string $className
+     * @param ClassMetadata<object> $metadata
      * @return void
      * @throws ORM\MappingException
      * @throws \UnexpectedValueException
@@ -178,9 +178,8 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
          * This is the actual type we have at this point, but we cannot change the
          * signature due to inheritance.
          *
-         * @var ORM\ClassMetadata $metadata
+         * @var ORM\ClassMetadata<object> $metadata
          */
-
         try {
             $class = $metadata->getReflectionClass();
             $classSchema = $this->getClassSchema($class->getName());
@@ -191,24 +190,28 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
 
         // Evaluate Entity annotation
         if (isset($classAnnotations[ORM\MappedSuperclass::class])) {
+            /** @var ORM\MappedSuperclass $mappedSuperclassAnnotation */
             $mappedSuperclassAnnotation = $classAnnotations[ORM\MappedSuperclass::class];
             if ($mappedSuperclassAnnotation->repositoryClass !== null) {
                 $metadata->setCustomRepositoryClass($mappedSuperclassAnnotation->repositoryClass);
             }
             $metadata->isMappedSuperclass = true;
         } elseif (isset($classAnnotations[Flow\Entity::class]) || isset($classAnnotations[ORM\Entity::class])) {
-            $entityAnnotation = isset($classAnnotations[Flow\Entity::class]) ? $classAnnotations[Flow\Entity::class] : $classAnnotations[ORM\Entity::class];
-            if ($entityAnnotation->repositoryClass !== null) {
+            /** @var Flow\Entity|ORM\Entity<object> $entityAnnotation */
+            $entityAnnotation = $classAnnotations[Flow\Entity::class] ?? $classAnnotations[ORM\Entity::class];
+            if ($entityAnnotation->repositoryClass !== null && is_subclass_of($entityAnnotation->repositoryClass, EntityRepository::class)) {
                 $metadata->setCustomRepositoryClass($entityAnnotation->repositoryClass);
             } elseif ($classSchema->getRepositoryClassName() !== null) {
-                if ($this->reflectionService->isClassImplementationOf($classSchema->getRepositoryClassName(), EntityRepository::class)) {
-                    $metadata->setCustomRepositoryClass($classSchema->getRepositoryClassName());
+                $repositoryClassName = $classSchema->getRepositoryClassName();
+                if (is_subclass_of($repositoryClassName, EntityRepository::class)) {
+                    $metadata->setCustomRepositoryClass($repositoryClassName);
                 }
             }
             if ($entityAnnotation->readOnly) {
                 $metadata->markReadOnly();
             }
         } elseif (isset($classAnnotations[Flow\ValueObject::class])) {
+            /** @var Flow\ValueObject $valueObjectAnnotation */
             $valueObjectAnnotation = $classAnnotations[Flow\ValueObject::class];
             if ($valueObjectAnnotation->embedded === true) {
                 $metadata->isEmbeddedClass = true;
@@ -225,6 +228,7 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
         // Evaluate Table annotation
         $primaryTable = [];
         if (isset($classAnnotations[ORM\Table::class])) {
+            /** @var ORM\Table $tableAnnotation */
             $tableAnnotation = $classAnnotations[ORM\Table::class];
             $primaryTable = [
                 'name' => $tableAnnotation->name,
@@ -276,6 +280,7 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
 
         // Evaluate @Cache annotation
         if (isset($classAnnotations[ORM\Cache::class])) {
+            /** @var ORM\Cache $cacheAnnotation */
             $cacheAnnotation = $classAnnotations[ORM\Cache::class];
             $cacheMap   = [
                 'region' => $cacheAnnotation->region,
@@ -287,6 +292,7 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
 
         // Evaluate NamedNativeQueries annotation
         if (isset($classAnnotations[ORM\NamedNativeQueries::class])) {
+            /** @var ORM\NamedNativeQueries $namedNativeQueriesAnnotation */
             $namedNativeQueriesAnnotation = $classAnnotations[ORM\NamedNativeQueries::class];
 
             foreach ($namedNativeQueriesAnnotation->value as $namedNativeQuery) {
@@ -301,6 +307,7 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
 
         // Evaluate SqlResultSetMappings annotation
         if (isset($classAnnotations[ORM\SqlResultSetMappings::class])) {
+            /** @var ORM\SqlResultSetMappings $sqlResultSetMappingsAnnotation */
             $sqlResultSetMappingsAnnotation = $classAnnotations[ORM\SqlResultSetMappings::class];
 
             foreach ($sqlResultSetMappingsAnnotation->value as $resultSetMapping) {
@@ -339,16 +346,10 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
 
         // Evaluate NamedQueries annotation
         if (isset($classAnnotations[ORM\NamedQueries::class])) {
+            /** @var ORM\NamedQueries $namedQueriesAnnotation */
             $namedQueriesAnnotation = $classAnnotations[ORM\NamedQueries::class];
 
-            if (!is_array($namedQueriesAnnotation->value)) {
-                throw new \UnexpectedValueException('@ORM\NamedQueries should contain an array of @ORM\NamedQuery annotations.');
-            }
-
             foreach ($namedQueriesAnnotation->value as $namedQuery) {
-                if (!($namedQuery instanceof ORM\NamedQuery)) {
-                    throw new \UnexpectedValueException('@ORM\NamedQueries should contain an array of @ORM\NamedQuery annotations.');
-                }
                 $metadata->addNamedQuery([
                     'name' => $namedQuery->name,
                     'query' => $namedQuery->query
@@ -358,17 +359,19 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
 
         // Evaluate InheritanceType annotation
         if (isset($classAnnotations[ORM\InheritanceType::class])) {
+            /** @var ORM\InheritanceType $inheritanceTypeAnnotation */
             $inheritanceTypeAnnotation = $classAnnotations[ORM\InheritanceType::class];
             $inheritanceType = constant('Doctrine\ORM\Mapping\ClassMetadata::INHERITANCE_TYPE_' . strtoupper($inheritanceTypeAnnotation->value));
 
             if ($inheritanceType !== ORM\ClassMetadata::INHERITANCE_TYPE_NONE) {
                 // Evaluate DiscriminatorColumn annotation
                 if (isset($classAnnotations[ORM\DiscriminatorColumn::class])) {
+                    /** @var ORM\DiscriminatorColumn $discriminatorColumnAnnotation */
                     $discriminatorColumnAnnotation = $classAnnotations[ORM\DiscriminatorColumn::class];
                     $discriminatorColumn = [
                         'name' => $discriminatorColumnAnnotation->name,
-                        'type' => $discriminatorColumnAnnotation->type,
-                        'length' => $discriminatorColumnAnnotation->length,
+                        'type' => $discriminatorColumnAnnotation->type ?: throw new \Exception('Cannot use untyped discriminator column', 1744137386),
+                        'length' => $discriminatorColumnAnnotation->length ?: throw new \Exception('Cannot use discriminator column without length', 1744137404),
                         'columnDefinition' => $discriminatorColumnAnnotation->columnDefinition
                     ];
                 } else {
@@ -379,6 +382,7 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
 
                 // Evaluate DiscriminatorMap annotation
                 if (isset($classAnnotations[ORM\DiscriminatorMap::class])) {
+                    /** @var ORM\DiscriminatorMap $discriminatorMapAnnotation */
                     $discriminatorMapAnnotation = $classAnnotations[ORM\DiscriminatorMap::class];
                     $discriminatorMap = $discriminatorMapAnnotation->value;
                 } else {
@@ -407,8 +411,11 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
 
         // Evaluate DoctrineChangeTrackingPolicy annotation
         if (isset($classAnnotations[ORM\ChangeTrackingPolicy::class])) {
+            /** @var ORM\ChangeTrackingPolicy $changeTrackingAnnotation */
             $changeTrackingAnnotation = $classAnnotations[ORM\ChangeTrackingPolicy::class];
-            $metadata->setChangeTrackingPolicy(constant('Doctrine\ORM\Mapping\ClassMetadata::CHANGETRACKING_' . strtoupper($changeTrackingAnnotation->value)));
+            $metadata->setChangeTrackingPolicy(constant(
+                'Doctrine\ORM\Mapping\ClassMetadata::CHANGETRACKING_' . strtoupper($changeTrackingAnnotation->value)
+            ));
         } else {
             $metadata->setChangeTrackingPolicy(ORM\ClassMetadata::CHANGETRACKING_DEFERRED_EXPLICIT);
         }
@@ -425,7 +432,11 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
             && !isset($primaryTable['uniqueConstraints'])) {
             $idProperties = array_keys($classSchema->getIdentityProperties());
             if (array_diff($idProperties, $metadata->getIdentifierFieldNames()) !== []) {
-                $uniqueIndexName = $this->truncateIdentifier('flow_identity_' . $primaryTable['name']);
+                $primaryTableName = $primaryTable['name'] ?? null;
+                if (!$primaryTableName) {
+                    throw new \Exception('Missing primary table name', 1744135393);
+                }
+                $uniqueIndexName = $this->truncateIdentifier('flow_identity_' . $primaryTableName);
                 foreach ($idProperties as $idProperty) {
                     $primaryTable['uniqueConstraints'][$uniqueIndexName]['columns'][] = $metadata->fieldMappings[$idProperty]['columnName'] ?? strtolower($idProperty);
                 }
@@ -534,11 +545,11 @@ protected function buildJoinTableColumnName($className)
      * Check if the referenced column name is set (and valid) and if not make sure
      * it is initialized properly.
      *
-     * @param array $joinColumns
-     * @param array $mapping
+     * @param array<mixed> $joinColumns
+     * @param array<mixed> $mapping
      * @param \ReflectionProperty $property
      * @param integer $direction regular or inverse mapping (use is to be coded)
-     * @return array
+     * @return array<mixed>
      */
     protected function buildJoinColumnsIfNeeded(array $joinColumns, array $mapping, \ReflectionProperty $property, $direction = self::MAPPING_REGULAR)
     {
@@ -574,7 +585,7 @@ protected function buildJoinColumnsIfNeeded(array $joinColumns, array $mapping,
     /**
      * Evaluate the property annotations and amend the metadata accordingly.
      *
-     * @param ORM\ClassMetadataInfo $metadata
+     * @param ORM\ClassMetadataInfo<object> $metadata
      * @return void
      * @throws ORM\MappingException
      */
@@ -601,7 +612,7 @@ protected function evaluatePropertyAnnotations(ORM\ClassMetadataInfo $metadata)
             $mapping['fieldName'] = $property->getName();
             $mapping['columnName'] = strtolower($property->getName());
             $mapping['targetEntity'] = $propertyMetaData['type'];
-            $mapping['nullable'] = $propertyMetaData['nullable'] ?? false;
+            $mapping['nullable'] = $propertyMetaData['nullable'];
 
             $joinColumns = $this->evaluateJoinColumnAnnotations($property);
 
@@ -621,13 +632,17 @@ protected function evaluatePropertyAnnotations(ORM\ClassMetadataInfo $metadata)
                 $mapping['inversedBy'] = $oneToOneAnnotation->inversedBy;
                 if ($oneToOneAnnotation->cascade !== null) {
                     $mapping['cascade'] = $oneToOneAnnotation->cascade;
+                    /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                 } elseif ($this->isValueObject($mapping['targetEntity'], $className)) {
                     $mapping['cascade'] = ['persist'];
+                    /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                 } elseif ($this->isAggregateRoot($mapping['targetEntity'], $className) === false) {
                     $mapping['cascade'] = ['all'];
                 }
                 // We need to apply our value for non-aggregate roots first, because Doctrine sets a default value for orphanRemoval (see #1127)
+                /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                 if ($this->isAggregateRoot($mapping['targetEntity'], $className) === false &&
+                    /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                     $this->isValueObject($mapping['targetEntity'], $className) === false) {
                     $mapping['orphanRemoval'] = true;
                 } elseif ($oneToOneAnnotation->orphanRemoval !== null) {
@@ -644,14 +659,18 @@ protected function evaluatePropertyAnnotations(ORM\ClassMetadataInfo $metadata)
                 }
                 if ($oneToManyAnnotation->cascade !== null) {
                     $mapping['cascade'] = $oneToManyAnnotation->cascade;
+                    /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                 } elseif ($this->isValueObject($mapping['targetEntity'], $className)) {
                     $mapping['cascade'] = ['persist'];
+                    /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                 } elseif ($this->isAggregateRoot($mapping['targetEntity'], $className) === false) {
                     $mapping['cascade'] = ['all'];
                 }
                 $mapping['indexBy'] = $oneToManyAnnotation->indexBy;
                 // We need to apply our value for non-aggregate roots first, because Doctrine sets a default value for orphanRemoval (see #1127)
+                /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                 if ($this->isAggregateRoot($mapping['targetEntity'], $className) === false &&
+                    /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                     $this->isValueObject($mapping['targetEntity'], $className) === false) {
                     $mapping['orphanRemoval'] = true;
                 } elseif ($oneToManyAnnotation->orphanRemoval !== null) {
@@ -712,8 +731,10 @@ protected function evaluatePropertyAnnotations(ORM\ClassMetadataInfo $metadata)
                 $mapping['joinColumns'] = $this->buildJoinColumnsIfNeeded($joinColumns, $mapping, $property);
                 if ($manyToOneAnnotation->cascade !== null) {
                     $mapping['cascade'] = $manyToOneAnnotation->cascade;
+                    /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                 } elseif ($this->isValueObject($mapping['targetEntity'], $className)) {
                     $mapping['cascade'] = ['persist'];
+                    /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                 } elseif ($this->isAggregateRoot($mapping['targetEntity'], $className) === false) {
                     $mapping['cascade'] = ['all'];
                 }
@@ -749,8 +770,10 @@ protected function evaluatePropertyAnnotations(ORM\ClassMetadataInfo $metadata)
                 $mapping['inversedBy'] = $manyToManyAnnotation->inversedBy;
                 if ($manyToManyAnnotation->cascade !== null) {
                     $mapping['cascade'] = $manyToManyAnnotation->cascade;
+                    /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                 } elseif ($this->isValueObject($mapping['targetEntity'], $className)) {
                     $mapping['cascade'] = ['persist'];
+                    /** @phpstan-ignore argument.type (this really is a class-string -.-) */
                 } elseif ($this->isAggregateRoot($mapping['targetEntity'], $className) === false) {
                     $mapping['cascade'] = ['all'];
                 }
@@ -798,7 +821,7 @@ protected function evaluatePropertyAnnotations(ORM\ClassMetadataInfo $metadata)
                             break;
                         default:
                             if (strpos($propertyMetaData['type'], '\\') !== false) {
-                                if ($this->reflectionService->isClassAnnotatedWith($propertyMetaData['type'], Flow\ValueObject::class)) {
+                                if (class_exists($propertyMetaData['type']) && $this->reflectionService->isClassAnnotatedWith($propertyMetaData['type'], Flow\ValueObject::class)) {
                                     $valueObjectAnnotation = $this->reflectionService->getClassAnnotation($propertyMetaData['type'], Flow\ValueObject::class);
                                     if ($valueObjectAnnotation && $valueObjectAnnotation->embedded === true) {
                                         $mapping['class'] = $propertyMetaData['type'];
@@ -833,11 +856,11 @@ protected function evaluatePropertyAnnotations(ORM\ClassMetadataInfo $metadata)
 
                 // Check for SequenceGenerator/TableGenerator definition
                 if ($seqGeneratorAnnotation = $this->reader->getPropertyAnnotation($property, ORM\SequenceGenerator::class)) {
-                    $metadata->setSequenceGeneratorDefinition([
+                    $metadata->setSequenceGeneratorDefinition(array_filter([
                         'sequenceName' => $seqGeneratorAnnotation->sequenceName,
                         'allocationSize' => $seqGeneratorAnnotation->allocationSize,
                         'initialValue' => $seqGeneratorAnnotation->initialValue
-                    ]);
+                    ]));
                 } elseif ($customGeneratorAnnotation = $this->reader->getPropertyAnnotation($property, ORM\CustomIdGenerator::class)) {
                     $metadata->setCustomGeneratorDefinition([
                         'class' => $customGeneratorAnnotation->class
@@ -847,10 +870,10 @@ protected function evaluatePropertyAnnotations(ORM\ClassMetadataInfo $metadata)
 
             // Evaluate @Cache annotation
             if (($cacheAnnotation = $this->reader->getPropertyAnnotation($property, ORM\Cache::class)) !== null) {
-                $metadata->enableAssociationCache($mapping['fieldName'], [
-                    'usage'         => constant('Doctrine\ORM\Mapping\ClassMetadata::CACHE_USAGE_' . $cacheAnnotation->usage),
-                    'region'        => $cacheAnnotation->region,
-                ]);
+                $metadata->enableAssociationCache($mapping['fieldName'], array_filter([
+                    'usage' => constant('Doctrine\ORM\Mapping\ClassMetadata::CACHE_USAGE_' . $cacheAnnotation->usage),
+                    'region' => $cacheAnnotation->region,
+                ]));
             }
         }
     }
@@ -861,8 +884,8 @@ protected function evaluatePropertyAnnotations(ORM\ClassMetadataInfo $metadata)
      * @param ORM\JoinTable $joinTableAnnotation
      * @param \ReflectionProperty $property
      * @param string $className
-     * @param array $mapping
-     * @return array
+     * @param array<mixed> $mapping
+     * @return array{name: string, schema: ?string, joinColumns: array<int,mixed>, inverseJoinColumns: array<int,mixed>}
      */
     protected function evaluateJoinTableAnnotation(ORM\JoinTable $joinTableAnnotation, \ReflectionProperty $property, $className, array $mapping)
     {
@@ -908,12 +931,12 @@ protected function evaluateJoinTableAnnotation(ORM\JoinTable $joinTableAnnotatio
     }
 
     /**
-     * Check for and build JoinColummn/JoinColumns annotations.
+     * Check for and build JoinColumn/JoinColumns annotations.
      *
      * If no annotations are found, a default is returned.
      *
      * @param \ReflectionProperty $property
-     * @return array
+     * @return array<int,array<mixed>>
      */
     protected function evaluateJoinColumnAnnotations(\ReflectionProperty $property)
     {
@@ -933,8 +956,8 @@ protected function evaluateJoinColumnAnnotations(\ReflectionProperty $property)
     /**
      * Evaluate the association overrides annotations and amend the metadata accordingly.
      *
-     * @param array $classAnnotations
-     * @param ORM\ClassMetadataInfo $metadata
+     * @param array<mixed> $classAnnotations
+     * @param ORM\ClassMetadataInfo<object> $metadata
      * @return void
      */
     protected function evaluateOverridesAnnotations(array $classAnnotations, ORM\ClassMetadataInfo $metadata)
@@ -992,9 +1015,9 @@ protected function evaluateOverridesAnnotations(array $classAnnotations, ORM\Cla
     /**
      * Evaluate the EntityListeners annotation and amend the metadata accordingly.
      *
-     * @param \ReflectionClass $class
-     * @param ORM\ClassMetadata $metadata
-     * @param array $classAnnotations
+     * @param \ReflectionClass<object> $class
+     * @param ORM\ClassMetadata<object> $metadata
+     * @param array<mixed> $classAnnotations
      * @return void
      * @throws ORM\MappingException
      */
@@ -1007,7 +1030,7 @@ protected function evaluateEntityListenersAnnotation(\ReflectionClass $class, OR
                 $listenerClassName = $metadata->fullyQualifiedClassName($item);
 
                 if ($listenerClassName === null || !class_exists($listenerClassName)) {
-                    throw ORM\MappingException::entityListenerClassNotFound($listenerClassName, $class->getName());
+                    throw ORM\MappingException::entityListenerClassNotFound($listenerClassName ?: 'null', $class->getName());
                 }
 
                 $hasMapping = false;
@@ -1034,8 +1057,8 @@ protected function evaluateEntityListenersAnnotation(\ReflectionClass $class, OR
     /**
      * Evaluate the lifecycle annotations and amend the metadata accordingly.
      *
-     * @param \ReflectionClass $class
-     * @param ORM\ClassMetadataInfo $metadata
+     * @param \ReflectionClass<object> $class
+     * @param ORM\ClassMetadataInfo<object> $metadata
      * @return void
      */
     protected function evaluateLifeCycleAnnotations(\ReflectionClass $class, ORM\ClassMetadataInfo $metadata)
@@ -1058,7 +1081,7 @@ protected function evaluateLifeCycleAnnotations(\ReflectionClass $class, ORM\Cla
      * Returns an array of callbacks for lifecycle annotations on the given method.
      *
      * @param \ReflectionMethod $method
-     * @return array
+     * @return array<int,array<int,mixed>>
      */
     protected function getMethodCallbacks(\ReflectionMethod $method)
     {
@@ -1120,7 +1143,7 @@ protected function getMaxIdentifierLength()
      * Returns whether the class with the specified name is transient. Only non-transient
      * classes, that is entities and mapped superclasses, should have their metadata loaded.
      *
-     * @param string $className
+     * @param class-string $className
      * @return boolean
      */
     public function isTransient($className)
@@ -1129,7 +1152,7 @@ public function isTransient($className)
             (
                 !$this->reflectionService->isClassAnnotatedWith($className, Flow\Entity::class) &&
                 !$this->reflectionService->isClassAnnotatedWith($className, Flow\ValueObject::class) &&
-                    !$this->reflectionService->isClassAnnotatedWith($className, ORM\Entity::class) &&
+                !$this->reflectionService->isClassAnnotatedWith($className, ORM\Entity::class) &&
                 !$this->reflectionService->isClassAnnotatedWith($className, ORM\MappedSuperclass::class) &&
                 !$this->reflectionService->isClassAnnotatedWith($className, ORM\Embeddable::class)
             );
@@ -1138,7 +1161,7 @@ public function isTransient($className)
     /**
      * Returns the names of all mapped (non-transient) classes known to this driver.
      *
-     * @return array
+     * @return array<int,class-string>
      */
     public function getAllClassNames()
     {
@@ -1169,7 +1192,7 @@ function ($className) {
      *
      * @param ORM\JoinColumn $joinColumnAnnotation
      * @param string $propertyName
-     * @return array
+     * @return array{name: ?string, unique: bool, nullable: bool, onDelete: mixed, columnDefinition: ?string, referencedColumnName: string}
      */
     protected function joinColumnToArray(ORM\JoinColumn $joinColumnAnnotation, $propertyName = null)
     {
@@ -1187,9 +1210,9 @@ protected function joinColumnToArray(ORM\JoinColumn $joinColumnAnnotation, $prop
      * Parse the given Column into an array
      *
      * @param ORM\Column $columnAnnotation
-     * @param array $mapping
+     * @param array<string,mixed> $mapping
      * @param string $fieldName
-     * @return array
+     * @return array<string,mixed>
      */
     protected function addColumnToMappingArray(ORM\Column $columnAnnotation, array $mapping = [], $fieldName = null)
     {
@@ -1222,11 +1245,12 @@ protected function addColumnToMappingArray(ORM\Column $columnAnnotation, array $
     /**
      * Returns the classname after stripping a potentially present Compiler::ORIGINAL_CLASSNAME_SUFFIX.
      *
-     * @param string $className
-     * @return string
+     * @param class-string $className
+     * @return class-string
      */
     protected function getUnproxiedClassName($className)
     {
+        /** @var class-string $className */
         $className = preg_replace('/' . Compiler::ORIGINAL_CLASSNAME_SUFFIX . '$/', '', $className);
 
         return $className;
@@ -1253,7 +1277,7 @@ private function getFetchMode($className, $fetchMode)
     /**
      * Checks if the specified class has a property annotated with Id
      *
-     * @param string $className Name of the class to check against
+     * @param class-string $className Name of the class to check against
      * @param string $methodName Name of the method to check against
      * @param string $methodDeclaringClassName Name of the class the method was originally declared in
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
@@ -1284,7 +1308,7 @@ public function hasRuntimeEvaluationsDefinition()
     /**
      * Returns runtime evaluations for a previously matched pointcut
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition()
     {
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/MigrationFinder.php b/Neos.Flow/Classes/Persistence/Doctrine/MigrationFinder.php
index 93555a066c..ced9438bae 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/MigrationFinder.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/MigrationFinder.php
@@ -45,7 +45,7 @@ public function findMigrations(string $directory, ?string $namespace = null): ar
                 $this->databasePlatformName
             ]);
             if (is_dir($path)) {
-                $files[] = glob($path . '/Version*.php');
+                $files[] = glob($path . '/Version*.php') ?: [];
             }
         }
 
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/ObjectValidationAndDeDuplicationListener.php b/Neos.Flow/Classes/Persistence/Doctrine/ObjectValidationAndDeDuplicationListener.php
index 92881f78b5..6732468bea 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/ObjectValidationAndDeDuplicationListener.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/ObjectValidationAndDeDuplicationListener.php
@@ -143,7 +143,7 @@ private function deduplicateValueObjectInsertions()
      * Validates the given object and throws an exception if validation fails.
      *
      * @param object $object
-     * @param \SplObjectStorage $validatedInstancesContainer
+     * @param \SplObjectStorage<object,mixed> $validatedInstancesContainer
      * @return void
      * @throws ObjectValidationFailedException
      */
@@ -151,21 +151,18 @@ private function validateObject($object, \SplObjectStorage $validatedInstancesCo
     {
         $className = $this->entityManager->getClassMetadata(get_class($object))->getName();
         $validator = $this->validatorResolver->getBaseValidatorConjunction($className, ['Persistence', 'Default']);
-        if ($validator === null) {
-            return;
-        }
 
         $validator->setValidatedInstancesContainer($validatedInstancesContainer);
         $validationResult = $validator->validate($object);
-        if ($validationResult->hasErrors()) {
+        if ($validationResult?->hasErrors()) {
             $errorMessages = '';
             $errorCount = 0;
-            $allErrors = $validationResult->getFlattenedErrors();
+            $allErrors = $validationResult->getFlattenedErrors() ?: [];
             foreach ($allErrors as $path => $errors) {
                 $errorMessages .= $path . ':' . PHP_EOL;
                 foreach ($errors as $error) {
                     $errorCount++;
-                    $errorMessages .= (string)$error . PHP_EOL;
+                    $errorMessages .= $error . PHP_EOL;
                 }
             }
             throw new ObjectValidationFailedException('An instance of "' . get_class($object) . '" failed to pass validation with ' . $errorCount . ' error(s): ' . PHP_EOL . $errorMessages, 1322585164);
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/PersistenceManager.php b/Neos.Flow/Classes/Persistence/Doctrine/PersistenceManager.php
index be1c1127c3..9be04cdcef 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/PersistenceManager.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/PersistenceManager.php
@@ -151,7 +151,7 @@ public function clearState(): void
      */
     public function isNewObject($object): bool
     {
-        if (!$object instanceof PersistenceMagicInterface) {
+        if (!($object instanceof PersistenceMagicInterface)) {
             return true;
         }
 
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/Query.php b/Neos.Flow/Classes/Persistence/Doctrine/Query.php
index 62ddd3ed8a..44592cb81d 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/Query.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/Query.php
@@ -64,7 +64,7 @@ class Query implements QueryInterface
     protected $entityManager;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $settings;
 
@@ -74,7 +74,7 @@ class Query implements QueryInterface
     protected $constraint;
 
     /**
-     * @var array
+     * @var array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING>
      */
     protected $orderings = [];
 
@@ -104,7 +104,7 @@ class Query implements QueryInterface
     protected $parameters;
 
     /**
-     * @var array
+     * @var ?array<string,string>
      */
     protected $joins;
 
@@ -140,10 +140,10 @@ public function injectEntityManager(EntityManagerInterface $entityManager)
      * Injects the Flow settings, the persistence part is kept
      * for further use.
      *
-     * @param array $settings
+     * @param array<string,mixed> $settings
      * @return void
      */
-    public function injectSettings(array $settings)
+    public function injectSettings(array $settings): void
     {
         $this->settings = $settings['persistence'];
     }
@@ -151,7 +151,7 @@ public function injectSettings(array $settings)
     /**
      * @param LoggerInterface $logger
      */
-    public function injectLogger(LoggerInterface $logger)
+    public function injectLogger(LoggerInterface $logger): void
     {
         $this->logger = $logger;
     }
@@ -186,7 +186,7 @@ public function execute(bool $cacheResult = false): QueryResultInterface
      * Really executes the query on the database.
      * This should only ever be executed from the QueryResult class.
      *
-     * @return array result set
+     * @return mixed result set
      * @throws DatabaseException
      * @throws DatabaseConnectionException
      * @throws DatabaseStructureException
@@ -283,7 +283,7 @@ public function count(): int
      *  'bar' => \Neos\Flow\Persistence\QueryInterface::ORDER_DESCENDING
      * )
      *
-     * @param array $orderings The property names to order by
+     * @param array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING> $orderings The property names to order by
      * @return QueryInterface
      * @api
      */
@@ -304,7 +304,7 @@ public function setOrderings(array $orderings): QueryInterface
      *  'bar' => \Neos\Flow\Persistence\QueryInterface::ORDER_DESCENDING
      * )
      *
-     * @return array
+     * @return array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING>
      * @api
      */
     public function getOrderings(): array
@@ -393,7 +393,7 @@ public function getOffset(): ?int
      * The constraint used to limit the result set. Returns $this to allow
      * for chaining (fluid interface)
      *
-     * @param object $constraint Some constraint, depending on the backend
+     * @param object|string $constraint Some constraint, depending on the backend
      * @return QueryInterface
      * @api
      */
@@ -456,7 +456,7 @@ public function logicalOr(mixed $constraint1, mixed ...$constraints)
     /**
      * Performs a logical negation of the given constraint
      *
-     * @param object $constraint Constraint to negate
+     * @param object|string $constraint Constraint to negate
      * @return object
      * @api
      */
@@ -618,7 +618,7 @@ public function greaterThanOrEqual(string $propertyName, $operand)
     /**
      * Add parameters to the query
      *
-     * @param array $parameters
+     * @param array<mixed> $parameters
      * @return void
      */
     public function addParameters($parameters)
@@ -632,7 +632,7 @@ public function addParameters($parameters)
     /**
      * Gets all defined query parameters for the query being constructed.
      *
-     * @return ArrayCollection
+     * @return ArrayCollection<int,Parameter>
      */
     public function getParameters()
     {
@@ -717,7 +717,7 @@ public function __wakeup()
             $this->queryBuilder->where($this->constraint);
         }
 
-        if (is_array($this->orderings)) {
+        if ($this->orderings !== []) {
             $aliases = $this->queryBuilder->getRootAliases();
             foreach ($this->orderings as $propertyName => $order) {
                 $this->queryBuilder->addOrderBy($aliases[0] . '.' . $propertyName, $order);
@@ -732,7 +732,7 @@ public function __wakeup()
         $this->queryBuilder->setMaxResults($this->limit);
         $this->queryBuilder->distinct($this->distinct);
         $this->queryBuilder->setParameters($this->parameters);
-        unset($this->parameters);
+        $this->parameters = new ArrayCollection();
     }
 
     /**
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/QueryResult.php b/Neos.Flow/Classes/Persistence/Doctrine/QueryResult.php
index e8004a88ab..a97d42307b 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/QueryResult.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/QueryResult.php
@@ -23,7 +23,7 @@
 class QueryResult implements QueryResultInterface
 {
     /**
-     * @var array
+     * @var ?array<mixed>
      * @Flow\Transient
      */
     protected $rows;
@@ -50,6 +50,7 @@ public function __construct(Query $query)
     /**
      * Loads the objects this QueryResult is supposed to hold
      *
+     * @phpstan-assert array<mixed> $this->rows
      * @return void
      */
     protected function initialize()
@@ -110,7 +111,7 @@ public function count(): int
     /**
      * Returns an array with the objects in the result set
      *
-     * @return array
+     * @return array<mixed>
      * @api
      */
     public function toArray(): array
@@ -209,6 +210,6 @@ public function rewind(): void
     public function valid(): bool
     {
         $this->initialize();
-        return current($this->rows) !== false;
+        return current($this->rows ?: []) !== false;
     }
 }
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/Repository.php b/Neos.Flow/Classes/Persistence/Doctrine/Repository.php
index 5749463bea..87017f174f 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/Repository.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/Repository.php
@@ -13,8 +13,8 @@
 
 use Doctrine\ORM\EntityManagerInterface;
 use Doctrine\ORM\EntityRepository;
+use Doctrine\ORM\Mapping\ClassMetadata;
 use Doctrine\ORM\QueryBuilder;
-use Doctrine\Persistence\Mapping\ClassMetadata;
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\Persistence\Exception\IllegalObjectTypeException;
 use Neos\Flow\Persistence\Exception\UnknownObjectException;
@@ -26,6 +26,7 @@
 /**
  * The Flow default Repository, based on Doctrine 2
  *
+ * @extends EntityRepository<object>
  * @api
  */
 abstract class Repository extends EntityRepository implements RepositoryInterface
@@ -50,7 +51,7 @@ abstract class Repository extends EntityRepository implements RepositoryInterfac
     protected $objectType;
 
     /**
-     * @var array
+     * @var array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING>
      */
     protected $defaultOrderings = [];
 
@@ -58,7 +59,7 @@ abstract class Repository extends EntityRepository implements RepositoryInterfac
      * Initializes a new Repository.
      *
      * @param EntityManagerInterface $entityManager The EntityManager to use.
-     * @param ClassMetadata|null $classMetadata The class descriptor.
+     * @param ClassMetadata<object>|null $classMetadata The class descriptor.
      */
     public function __construct(EntityManagerInterface $entityManager, ?ClassMetadata $classMetadata = null)
     {
@@ -70,8 +71,12 @@ public function __construct(EntityManagerInterface $entityManager, ?ClassMetadat
             }
             /** @var class-string $objectType */
             $this->objectType = $objectType;
+            /** @var ?ClassMetadata<object> $classMetadata */
             $classMetadata = $entityManager->getClassMetadata($this->objectType);
         }
+        if (!$classMetadata) {
+            throw new \Exception('Unable to resolve class metadata for ' . $this->objectType);
+        }
         parent::__construct($entityManager, $classMetadata);
         $this->entityManager = $this->_em;
     }
@@ -97,9 +102,8 @@ public function getEntityClassName(): string
      */
     public function add($object): void
     {
-        if (!is_object($object) || !($object instanceof $this->objectType)) {
-            $type = (is_object($object) ? get_class($object) : gettype($object));
-            throw new IllegalObjectTypeException('The value given to add() was ' . $type . ' , however the ' . get_class($this) . ' can only store ' . $this->objectType . ' instances.', 1517408062);
+        if (!($object instanceof $this->objectType)) {
+            throw new IllegalObjectTypeException('The value given to add() was ' . get_class($object) . ' , however the ' . get_class($this) . ' can only store ' . $this->objectType . ' instances.', 1517408062);
         }
         $this->entityManager->persist($object);
     }
@@ -114,9 +118,8 @@ public function add($object): void
      */
     public function remove($object): void
     {
-        if (!is_object($object) || !($object instanceof $this->objectType)) {
-            $type = (is_object($object) ? get_class($object) : gettype($object));
-            throw new IllegalObjectTypeException('The value given to remove() was ' . $type . ' , however the ' . get_class($this) . ' can only handle ' . $this->objectType . ' instances.', 1517408067);
+        if (!($object instanceof $this->objectType)) {
+            throw new IllegalObjectTypeException('The value given to remove() was ' . get_class($object) . ' , however the ' . get_class($this) . ' can only handle ' . $this->objectType . ' instances.', 1517408067);
         }
         $this->entityManager->remove($object);
     }
@@ -124,9 +127,10 @@ public function remove($object): void
     /**
      * Finds all entities in the repository.
      *
-     * @phpstan-ignore-next-line we don't satisfy the contract of doctrines repository as we don't return a simple array.
-     * @return QueryResultInterface The query result
+     * @return QueryResultInterface<object> The query result
      * @api
+     * (don't know how generics work here yet and ignoring method.childReturnType has no effect)
+     * @phpstan-ignore-next-line
      */
     public function findAll(): QueryResultInterface
     {
@@ -136,7 +140,7 @@ public function findAll(): QueryResultInterface
     /**
      * Find all objects and return an IterableResult
      *
-     * @return iterable
+     * @return iterable<object>
      */
     public function findAllIterator(): iterable
     {
@@ -222,7 +226,7 @@ public function removeAll(): void
      *  'bar' => \Neos\Flow\Persistence\QueryInterface::ORDER_DESCENDING
      * )
      *
-     * @param array $defaultOrderings The property names to order by by default
+     * @param array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING> $defaultOrderings The property names to order by by default
      * @return void
      * @api
      */
@@ -257,7 +261,7 @@ public function update($object): void
      *  - countBy<PropertyName>($value, $caseSensitive = true)
      *
      * @param string $method Name of the method
-     * @param array $arguments The arguments
+     * @param array<mixed> $arguments The arguments
      * @return mixed The result of the repository method
      * @api
      */
diff --git a/Neos.Flow/Classes/Persistence/Doctrine/Service.php b/Neos.Flow/Classes/Persistence/Doctrine/Service.php
index 2c18e36a20..c3d3496588 100644
--- a/Neos.Flow/Classes/Persistence/Doctrine/Service.php
+++ b/Neos.Flow/Classes/Persistence/Doctrine/Service.php
@@ -42,6 +42,7 @@
 use Doctrine\Migrations\Version\ExecutionResult;
 use Doctrine\Migrations\Version\Version;
 use Doctrine\ORM\EntityManagerInterface;
+use Doctrine\ORM\Mapping\ClassMetadata;
 use Doctrine\ORM\Mapping\MappingException;
 use Doctrine\ORM\Tools\SchemaTool;
 use Doctrine\ORM\Tools\SchemaValidator;
@@ -97,7 +98,7 @@ class Service
      * Validates the metadata mapping for Doctrine, using the SchemaValidator
      * of Doctrine.
      *
-     * @return array
+     * @return array<int|string,array<string>>
      */
     public function validateMapping(): array
     {
@@ -167,7 +168,7 @@ public function compileProxies(): void
      * Returns information about which entities exist and possibly if their
      * mapping information contains errors or not.
      *
-     * @return array
+     * @return array<class-string,string|ClassMetadata<object>>
      */
     public function getEntityStatus(): array
     {
@@ -192,12 +193,12 @@ public function getEntityStatus(): array
      * Run DQL and return the result as-is.
      *
      * @param string $dql
-     * @param integer $hydrationMode
+     * @param 1|2|3|4|5|6|string|null $hydrationMode
      * @param int|null $firstResult
      * @param int|null $maxResult
      * @return mixed
      */
-    public function runDql(string $dql, int $hydrationMode = \Doctrine\ORM\Query::HYDRATE_OBJECT, ?int $firstResult = null, ?int $maxResult = null)
+    public function runDql(string $dql, int|string|null $hydrationMode = \Doctrine\ORM\Query::HYDRATE_OBJECT, ?int $firstResult = null, ?int $maxResult = null)
     {
         $query = $this->entityManager->createQuery($dql);
         if ($firstResult !== null) {
@@ -489,7 +490,7 @@ public function markAsMigrated(string $version, bool $markAsMigrated, ?string $o
         if ($version === 'all') {
             if ($markAsMigrated === false) {
                 foreach ($executedMigrations->getItems() as $availableMigration) {
-                    $this->mark($output, $availableMigration->getVersion(), false, $executedMigrations, !$markAsMigrated, $overrideMigrationFolderName);
+                    $this->mark($output, $availableMigration->getVersion(), false, $executedMigrations, true, $overrideMigrationFolderName);
                 }
             }
 
@@ -619,7 +620,7 @@ public function getMigrationStatus(?string $overrideMigrationFolderName = null):
      * @param boolean $diffAgainstCurrent
      * @param string|null $filterExpression
      * @param string|null $overrideMigrationFolderName
-     * @return array Path to the new file
+     * @return array<int,mixed> Path to the new file
      * @throws DBALException
      * @throws FilesException
      */
@@ -694,10 +695,10 @@ public function getMigrationFolderName(): string
      *
      * @param Schema $schema
      * @param AbstractPlatform $platform
-     * @param array $tableNames
+     * @param array<string> $tableNames
      * @param string $search
      * @param string $replace
-     * @return array
+     * @return array{drop: array<int,string>, add: array<int,string>}
      */
     public static function getForeignKeyHandlingSql(Schema $schema, AbstractPlatform $platform, array $tableNames, string $search, string $replace): array
     {
diff --git a/Neos.Flow/Classes/Persistence/EmptyQueryResult.php b/Neos.Flow/Classes/Persistence/EmptyQueryResult.php
index ce291f11d6..3f1e5ed430 100644
--- a/Neos.Flow/Classes/Persistence/EmptyQueryResult.php
+++ b/Neos.Flow/Classes/Persistence/EmptyQueryResult.php
@@ -58,7 +58,7 @@ public function getFirst()
     /**
      * Returns an empty array
      *
-     * @return array
+     * @return array<mixed>
      * @api
      */
     public function toArray(): array
@@ -68,6 +68,7 @@ public function toArray(): array
 
     public function current(): mixed
     {
+        /** @phpstan-ignore return.type (I don't see any "object" requirement here) */
         return null;
     }
 
diff --git a/Neos.Flow/Classes/Persistence/PersistenceManagerInterface.php b/Neos.Flow/Classes/Persistence/PersistenceManagerInterface.php
index 5aff47fa89..80888fb1e6 100644
--- a/Neos.Flow/Classes/Persistence/PersistenceManagerInterface.php
+++ b/Neos.Flow/Classes/Persistence/PersistenceManagerInterface.php
@@ -22,7 +22,7 @@ interface PersistenceManagerInterface
     /**
      * Injects the Flow settings, called by Flow.
      *
-     * @param array $settings
+     * @param array<string,mixed> $settings
      * @return void
      * @api
      */
diff --git a/Neos.Flow/Classes/Persistence/QueryInterface.php b/Neos.Flow/Classes/Persistence/QueryInterface.php
index 910f37d9d8..f7d6334bae 100644
--- a/Neos.Flow/Classes/Persistence/QueryInterface.php
+++ b/Neos.Flow/Classes/Persistence/QueryInterface.php
@@ -129,7 +129,7 @@ public function count(): int;
      *  'bar' => \Neos\Flow\Persistence\QueryInterface::ORDER_DESCENDING
      * )
      *
-     * @param array $orderings The property names to order by
+     * @param array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING> $orderings The property names to order by
      * @return QueryInterface
      * @api
      */
@@ -142,7 +142,7 @@ public function setOrderings(array $orderings): QueryInterface;
      *  'bar' => \Neos\Flow\Persistence\QueryInterface::ORDER_DESCENDING
      * )
      *
-     * @return array
+     * @return array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING>
      * @api
      */
     public function getOrderings(): array;
diff --git a/Neos.Flow/Classes/Persistence/QueryResultInterface.php b/Neos.Flow/Classes/Persistence/QueryResultInterface.php
index 001d247753..1c260a280f 100644
--- a/Neos.Flow/Classes/Persistence/QueryResultInterface.php
+++ b/Neos.Flow/Classes/Persistence/QueryResultInterface.php
@@ -14,6 +14,8 @@
 /**
  * A lazy result list that is returned by Query::execute()
  *
+ * @extends \Iterator<mixed,object>
+ * @extends \ArrayAccess<mixed,object>
  * @api
  */
 interface QueryResultInterface extends \Countable, \Iterator, \ArrayAccess
@@ -37,7 +39,7 @@ public function getFirst();
     /**
      * Returns an array with the objects in the result set
      *
-     * @return array
+     * @return array<mixed>
      * @api
      */
     public function toArray(): array;
diff --git a/Neos.Flow/Classes/Persistence/Repository.php b/Neos.Flow/Classes/Persistence/Repository.php
index cea6418226..3ace4da0cf 100644
--- a/Neos.Flow/Classes/Persistence/Repository.php
+++ b/Neos.Flow/Classes/Persistence/Repository.php
@@ -36,7 +36,7 @@ abstract class Repository implements RepositoryInterface
     protected $entityClassName;
 
     /**
-     * @var array
+     * @var array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING>
      */
     protected $defaultOrderings = [];
 
@@ -78,9 +78,8 @@ public function getEntityClassName(): string
      */
     public function add($object): void
     {
-        if (!is_object($object) || !($object instanceof $this->entityClassName)) {
-            $type = (is_object($object) ? get_class($object) : gettype($object));
-            throw new IllegalObjectTypeException('The value given to add() was ' . $type . ' , however the ' . get_class($this) . ' can only store ' . $this->entityClassName . ' instances.', 1298403438);
+        if (!($object instanceof $this->entityClassName)) {
+            throw new IllegalObjectTypeException('The value given to add() was ' . get_class($object) . ' , however the ' . get_class($this) . ' can only store ' . $this->entityClassName . ' instances.', 1298403438);
         }
         $this->persistenceManager->add($object);
     }
@@ -95,9 +94,8 @@ public function add($object): void
      */
     public function remove($object): void
     {
-        if (!is_object($object) || !($object instanceof $this->entityClassName)) {
-            $type = (is_object($object) ? get_class($object) : gettype($object));
-            throw new IllegalObjectTypeException('The value given to remove() was ' . $type . ' , however the ' . get_class($this) . ' can only handle ' . $this->entityClassName . ' instances.', 1298403442);
+        if (!($object instanceof $this->entityClassName)) {
+            throw new IllegalObjectTypeException('The value given to remove() was ' . get_class($object) . ' , however the ' . get_class($this) . ' can only handle ' . $this->entityClassName . ' instances.', 1298403442);
         }
         $this->persistenceManager->remove($object);
     }
@@ -174,7 +172,7 @@ public function removeAll(): void
      *  'bar' => \Neos\Flow\Persistence\QueryInterface::ORDER_DESCENDING
      * )
      *
-     * @param array $defaultOrderings The property names to order by by default
+     * @param array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING> $defaultOrderings The property names to order by by default
      * @return void
      * @api
      */
@@ -192,9 +190,8 @@ public function setDefaultOrderings(array $defaultOrderings): void
      */
     public function update($object): void
     {
-        if (!is_object($object) || !($object instanceof $this->entityClassName)) {
-            $type = (is_object($object) ? get_class($object) : gettype($object));
-            throw new IllegalObjectTypeException('The value given to update() was ' . $type . ' , however the ' . get_class($this) . ' can only store ' . $this->entityClassName . ' instances.', 1249479625);
+        if (!($object instanceof $this->entityClassName)) {
+            throw new IllegalObjectTypeException('The value given to update() was ' . get_class($object) . ' , however the ' . get_class($this) . ' can only store ' . $this->entityClassName . ' instances.', 1249479625);
         }
 
         $this->persistenceManager->update($object);
@@ -209,7 +206,7 @@ public function update($object): void
      *  - countBy<PropertyName>($value, $caseSensitive = true)
      *
      * @param string $method Name of the method
-     * @param array $arguments The arguments
+     * @param array<mixed> $arguments The arguments
      * @return mixed The result of the repository method
      * @api
      */
diff --git a/Neos.Flow/Classes/Persistence/RepositoryInterface.php b/Neos.Flow/Classes/Persistence/RepositoryInterface.php
index 12dcf762dd..23f4e0c6af 100644
--- a/Neos.Flow/Classes/Persistence/RepositoryInterface.php
+++ b/Neos.Flow/Classes/Persistence/RepositoryInterface.php
@@ -93,7 +93,7 @@ public function removeAll(): void;
      *  'bar' => \Neos\Flow\Persistence\QueryInterface::ORDER_DESCENDING
      * )
      *
-     * @param array $defaultOrderings The property names to order by by default
+     * @param array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING> $defaultOrderings The property names to order by by default
      * @return void
      * @api
      */
@@ -117,7 +117,7 @@ public function update($object): void;
      *  - countBy<PropertyName>($value, $caseSensitive = true)
      *
      * @param string $method Name of the method
-     * @param array $arguments The arguments
+     * @param array<mixed> $arguments The arguments
      * @return mixed The result of the repository method
      * @api
      */
diff --git a/Neos.Flow/Classes/Property/PropertyMapper.php b/Neos.Flow/Classes/Property/PropertyMapper.php
index 8344fc0d59..8ab371830a 100644
--- a/Neos.Flow/Classes/Property/PropertyMapper.php
+++ b/Neos.Flow/Classes/Property/PropertyMapper.php
@@ -53,14 +53,14 @@ class PropertyMapper
      * 3. Dimension: Priority
      * Value: Type Converter instance
      *
-     * @var array
+     * @var array<string,array<string,array<int,class-string<TypeConverterInterface>>>>
      */
     protected $typeConverters = [];
 
     /**
      * A list of property mapping messages (errors, warnings) which have occured on last mapping.
      *
-     * @var Result
+     * @var ?Result
      */
     protected $messages;
 
@@ -85,7 +85,7 @@ public function initializeObject()
      * Returns all class names implementing the TypeConverterInterface.
      *
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of type converter implementations
+     * @return array<class-string<TypeConverterInterface>> Array of type converter implementations
      * @Flow\CompileStatic
      */
     public static function getTypeConverterImplementationClassNames($objectManager)
@@ -106,9 +106,10 @@ public static function getTypeConverterImplementationClassNames($objectManager)
      * @return mixed an instance of $targetType
      * @throws Exception
      * @throws SecurityException
+     * @phpstan-assert Result $this->getMessages()
      * @api
      */
-    public function convert($source, $targetType, ?PropertyMappingConfigurationInterface $configuration = null)
+    public function convert($source, string $targetType, ?PropertyMappingConfigurationInterface $configuration = null)
     {
         if ($configuration === null) {
             $configuration = $this->buildPropertyMappingConfiguration();
@@ -123,9 +124,10 @@ public function convert($source, $targetType, ?PropertyMappingConfigurationInter
             }
 
             return $result;
-        } catch (SecurityException $exception) {
+        } catch (SecurityException $exception) { /** @phpstan-ignore catch.neverThrown (AOP I guess) */
             throw $exception;
         } catch (\Exception $exception) {
+            /** @phpstan-ignore greater.alwaysFalse (Not sure about this tbh) */
             throw new PropertyException('Could not convert target type "' . $targetType . '"' . (count($currentPropertyPath) > 0 ? ', at property path "' . implode('.', $currentPropertyPath) . '"' : '') . ': ' . $exception->getMessage(), 1297759968, $exception);
         }
     }
@@ -133,7 +135,7 @@ public function convert($source, $targetType, ?PropertyMappingConfigurationInter
     /**
      * Get the messages of the last Property Mapping
      *
-     * @return Result
+     * @return ?Result
      * @api
      */
     public function getMessages()
@@ -147,7 +149,7 @@ public function getMessages()
      * @param mixed $source the source data to map. MUST be a simple type, NO object allowed!
      * @param string $targetType The type of the target; can be either a class name or a simple type.
      * @param PropertyMappingConfigurationInterface $configuration Configuration for the property mapping.
-     * @param array $currentPropertyPath The property path currently being mapped; used for knowing the context in case an exception is thrown.
+     * @param array<int,string> $currentPropertyPath The property path currently being mapped; used for knowing the context in case an exception is thrown.
      * @return mixed an instance of $targetType
      * @throws Exception\TypeConverterException
      * @throws Exception\InvalidPropertyMappingConfigurationException
@@ -175,10 +177,6 @@ protected function doMapping($source, $targetType, PropertyMappingConfigurationI
         $typeConverter = $this->findTypeConverter($source, $targetType, $configuration);
         $targetType = $typeConverter->getTargetTypeForSource($source, $targetType, $configuration);
 
-        if (!is_object($typeConverter) || !($typeConverter instanceof TypeConverterInterface)) {
-            throw new Exception\TypeConverterException('Type converter for "' . $source . '" -> "' . $targetType . '" not found.');
-        }
-
         $convertedChildProperties = [];
         foreach ($typeConverter->getSourceChildPropertiesToBeConverted($source) as $sourcePropertyName => $sourcePropertyValue) {
             $targetPropertyName = $configuration->getTargetPropertyName($sourcePropertyName);
@@ -210,7 +208,7 @@ protected function doMapping($source, $targetType, PropertyMappingConfigurationI
         $result = $typeConverter->convertFrom($source, $targetType, $convertedChildProperties, $configuration);
 
         if ($result instanceof Error) {
-            $this->messages->forProperty(implode('.', $currentPropertyPath))->addError($result);
+            $this->messages?->forProperty(implode('.', $currentPropertyPath))->addError($result);
         }
 
         return $result;
@@ -232,9 +230,6 @@ protected function findTypeConverter($source, $targetType, PropertyMappingConfig
             return $configuration->getTypeConverter();
         }
 
-        if (!is_string($targetType)) {
-            throw new Exception\InvalidTargetException('The target type was no string, but of type "' . gettype($targetType) . '"', 1297941727);
-        }
         $normalizedTargetType = TypeHandling::normalizeType($targetType);
         $truncatedTargetType = TypeHandling::truncateElementType($normalizedTargetType);
         $converter = null;
@@ -296,7 +291,7 @@ protected function findFirstEligibleTypeConverterInObjectHierarchy($source, $sou
             }
         }
 
-        $converters = $this->getConvertersForInterfaces($convertersForSource, class_implements($targetClass));
+        $converters = $this->getConvertersForInterfaces($convertersForSource, class_implements($targetClass) ?: []);
         $converter = $this->findEligibleConverterWithHighestPriority($converters, $source, $targetType);
 
         if ($converter !== null) {
@@ -341,9 +336,9 @@ protected function findEligibleConverterWithHighestPriority($converters, $source
     }
 
     /**
-     * @param array $convertersForSource
-     * @param array $interfaceNames
-     * @return array
+     * @param array<string,array<int,class-string<TypeConverterInterface>>> $convertersForSource
+     * @param array<class-string> $interfaceNames
+     * @return array<int,class-string<TypeConverterInterface>>
      * @throws DuplicateTypeConverterException
      */
     protected function getConvertersForInterfaces(array $convertersForSource, array $interfaceNames)
@@ -353,7 +348,7 @@ protected function getConvertersForInterfaces(array $convertersForSource, array
             if (isset($convertersForSource[$implementedInterface])) {
                 foreach ($convertersForSource[$implementedInterface] as $priority => $converter) {
                     if (isset($convertersForInterface[$priority])) {
-                        throw new DuplicateTypeConverterException('There exist at least two converters which handle the conversion to an interface with priority "' . $priority . '". ' . get_class($convertersForInterface[$priority]) . ' and ' . get_class($converter), 1297951338);
+                        throw new DuplicateTypeConverterException('There exist at least two converters which handle the conversion to an interface with priority "' . $priority . '". ' . $convertersForInterface[$priority] . ' and ' . $converter, 1297951338);
                     }
                     $convertersForInterface[$priority] = $converter;
                 }
@@ -367,7 +362,7 @@ protected function getConvertersForInterfaces(array $convertersForSource, array
      * Determine the type of the source data, or throw an exception if source was an unsupported format.
      *
      * @param mixed $source
-     * @return array Possible source types (single value for simple typed source, multiple values for object source)
+     * @return array<string> Possible source types (single value for simple typed source, multiple values for object source)
      * @throws Exception\InvalidSourceException
      */
     protected function determineSourceTypes($source)
@@ -396,7 +391,7 @@ protected function determineSourceTypes($source)
     /**
      * Collects all TypeConverter implementations in a multi-dimensional array with source and target types.
      *
-     * @return array
+     * @return array<string,array<string,array<int,class-string<TypeConverterInterface>>>>
      * @throws Exception\DuplicateTypeConverterException
      * @see getTypeConverters
      */
@@ -405,7 +400,6 @@ protected function prepareTypeConverterMap()
         $typeConverterMap = [];
         $typeConverterClassNames = static::getTypeConverterImplementationClassNames($this->objectManager);
         foreach ($typeConverterClassNames as $typeConverterClassName) {
-            /** @var TypeConverterInterface $typeConverter */
             $typeConverter = $this->objectManager->get($typeConverterClassName);
             foreach ($typeConverter->getSupportedSourceTypes() as $supportedSourceType) {
                 $normalizedSourceType = TypeHandling::normalizeType($supportedSourceType);
@@ -430,7 +424,7 @@ protected function prepareTypeConverterMap()
      * 3. Dimension: Priority
      * Value: Type Converter instance
      *
-     * @return array
+     * @return array<string,array<string,array<int,class-string<TypeConverterInterface>>>>
      */
     public function getTypeConverters()
     {
diff --git a/Neos.Flow/Classes/Property/PropertyMappingConfiguration.php b/Neos.Flow/Classes/Property/PropertyMappingConfiguration.php
index dc6021c1cb..c92713b00f 100644
--- a/Neos.Flow/Classes/Property/PropertyMappingConfiguration.php
+++ b/Neos.Flow/Classes/Property/PropertyMappingConfiguration.php
@@ -30,21 +30,21 @@ class PropertyMappingConfiguration implements PropertyMappingConfigurationInterf
      * 2. Dimension: Configuration Key
      * Value: Configuration Value
      *
-     * @var array
+     * @var array<class-string<TypeConverterInterface>,array<int|string,mixed>>
      */
     protected $configuration;
 
     /**
      * Stores the configuration for specific child properties.
      *
-     * @var array<PropertyMappingConfiguration>
+     * @var array<string,PropertyMappingConfiguration>
      */
     protected $subConfigurationForProperty = [];
 
     /**
      * Keys which should be renamed
      *
-     * @var array
+     * @var array<string,string>
      */
     protected $mapping = [];
 
@@ -56,21 +56,21 @@ class PropertyMappingConfiguration implements PropertyMappingConfigurationInterf
     /**
      * List of allowed property names to be converted
      *
-     * @var array
+     * @var array<string,string>
      */
     protected $propertiesToBeMapped = [];
 
     /**
      * List of property names to be skipped during property mapping
      *
-     * @var array
+     * @var array<string,string>
      */
     protected $propertiesToSkip = [];
 
     /**
      * List of disallowed property names which will be ignored while property mapping
      *
-     * @var array
+     * @var array<string,string>
      */
     protected $propertiesNotToBeMapped = [];
 
@@ -260,7 +260,7 @@ public function getTargetPropertyName($sourcePropertyName)
 
     /**
      * @param string $typeConverterClassName
-     * @param string $key
+     * @param string|int $key
      * @return mixed configuration value for the specific $typeConverterClassName. Can be used by Type Converters to fetch converter-specific configuration.
      * @api
      */
@@ -290,8 +290,8 @@ public function setMapping($sourcePropertyName, $targetPropertyName)
     /**
      * Set all options for the given $typeConverter.
      *
-     * @param string $typeConverter class name of type converter
-     * @param array $options
+     * @param class-string<TypeConverterInterface> $typeConverter class name of type converter
+     * @param array<mixed> $options
      * @return PropertyMappingConfiguration this
      * @api
      */
@@ -306,7 +306,7 @@ public function setTypeConverterOptions($typeConverter, array $options)
     /**
      * Set a single option (denoted by $optionKey) for the given $typeConverter.
      *
-     * @param string $typeConverter class name of type converter
+     * @param class-string<TypeConverterInterface> $typeConverter class name of type converter
      * @param int|string $optionKey
      * @param mixed $optionValue
      * @return PropertyMappingConfiguration this
@@ -326,13 +326,18 @@ public function setTypeConverterOption($typeConverter, $optionKey, $optionValue)
      * When setting an option on a subclassed type converter, this option must also be set on
      * all its parent type converters.
      *
-     * @param string $typeConverter The type converter class
-     * @return array Class names of type converters
+     * @param class-string<TypeConverterInterface> $typeConverter The type converter class
+     * @return array<int|string,class-string<TypeConverterInterface>> Class names of type converters
      */
     protected function getTypeConvertersWithParentClasses($typeConverter)
     {
         $typeConverterClasses = class_parents($typeConverter);
-        $typeConverterClasses = $typeConverterClasses === false ? [] : $typeConverterClasses;
+        $typeConverterClasses = $typeConverterClasses === false
+            ? []
+            : array_filter(
+                $typeConverterClasses,
+                fn (string $parentClassName): bool => is_subclass_of($parentClassName, TypeConverterInterface::class)
+            );
         $typeConverterClasses[] = $typeConverter;
         return $typeConverterClasses;
     }
@@ -355,7 +360,7 @@ public function forProperty($propertyPath)
     /**
      * Traverse the property configuration. Only used by forProperty().
      *
-     * @param array $splittedPropertyPath
+     * @param array<string> $splittedPropertyPath
      * @return PropertyMappingConfiguration (or a subclass thereof)
      */
     public function traverseProperties(array $splittedPropertyPath)
diff --git a/Neos.Flow/Classes/Property/PropertyMappingConfigurationInterface.php b/Neos.Flow/Classes/Property/PropertyMappingConfigurationInterface.php
index 786e08b003..55622e78c7 100644
--- a/Neos.Flow/Classes/Property/PropertyMappingConfigurationInterface.php
+++ b/Neos.Flow/Classes/Property/PropertyMappingConfigurationInterface.php
@@ -70,7 +70,7 @@ public function getTargetPropertyName($sourcePropertyName);
 
     /**
      * @param string $typeConverterClassName
-     * @param string $key
+     * @param string|int $key
      * @return mixed configuration value for the specific $typeConverterClassName. Can be used by Type Converters to fetch converter-specific configuration
      * @api
      */
diff --git a/Neos.Flow/Classes/Property/TypeConverter/ArrayConverter.php b/Neos.Flow/Classes/Property/TypeConverter/ArrayConverter.php
index ca088c34cb..216f8b2bc8 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/ArrayConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/ArrayConverter.php
@@ -112,9 +112,9 @@ class ArrayConverter extends AbstractTypeConverter
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
-     * @return array
+     * @return array<mixed>
      * @throws InvalidPropertyMappingConfigurationException
      * @throws InvalidSourceException
      * @throws TypeConverterException
@@ -146,9 +146,13 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
             $exportType = $this->getResourceExportType($configuration);
             switch ($exportType) {
                 case self::RESOURCE_EXPORT_TYPE_BASE64:
+                    $fileContent = file_get_contents('resource://' . $source->getSha1());
+                    if ($fileContent === false) {
+                        throw new \Exception('Failed to fetch content for resource ' . $source->getSha1(), 1744060115);
+                    }
                     return [
                         'filename' => $source->getFilename(),
-                        'data' => base64_encode(file_get_contents('resource://' . $source->getSha1())),
+                        'data' => base64_encode($fileContent),
                         'collectionName' => $source->getCollectionName(),
                         'relativePublicationPath' => $source->getRelativePublicationPath(),
                         'mediaType' => $source->getMediaType(),
@@ -159,7 +163,13 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
                     if ($sourceStream === false) {
                         throw new InvalidSourceException(sprintf('Could not get stream of resource "%s" (%s). This might be caused by a broken resource object and can be fixed by running the "resource:clean" command.', $source->getFilename(), $source->getSha1()), 1435842312);
                     }
+                    if (!$configuration) {
+                        throw new \Exception('Cannot resolve target path without a property mapping configuration', 1744060031);
+                    }
                     $targetStream = fopen($configuration->getConfigurationValue(ArrayConverter::class, self::CONFIGURATION_RESOURCE_SAVE_PATH) . '/' . $source->getSha1(), 'w');
+                    if ($targetStream === false) {
+                        throw new \Exception('Could not open target stream', 1744060053);
+                    }
                     stream_copy_to_stream($sourceStream, $targetStream);
                     fclose($targetStream);
                     fclose($sourceStream);
@@ -181,7 +191,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
 
     /**
      * @param PropertyMappingConfigurationInterface|null $configuration
-     * @return string
+     * @return non-empty-string
      * @throws InvalidPropertyMappingConfigurationException
      */
     protected function getStringDelimiter(?PropertyMappingConfigurationInterface $configuration = null)
@@ -195,6 +205,8 @@ protected function getStringDelimiter(?PropertyMappingConfigurationInterface $co
             return self::DEFAULT_STRING_DELIMITER;
         } elseif (!is_string($stringDelimiter)) {
             throw new InvalidPropertyMappingConfigurationException(sprintf('CONFIGURATION_STRING_DELIMITER must be of type string, "%s" given', (is_object($stringDelimiter) ? get_class($stringDelimiter) : gettype($stringDelimiter))), 1368433339);
+        } elseif ($stringDelimiter === '') {
+            throw new InvalidPropertyMappingConfigurationException('CONFIGURATION_STRING_DELIMITER must not be empty', 1744060278);
         }
 
         return $stringDelimiter;
diff --git a/Neos.Flow/Classes/Property/TypeConverter/ArrayFromObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/ArrayFromObjectConverter.php
index 0c5d63e1d6..772798dbac 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/ArrayFromObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/ArrayFromObjectConverter.php
@@ -50,7 +50,7 @@ class ArrayFromObjectConverter extends AbstractTypeConverter
      * Convert all properties in the source array
      *
      * @param mixed $source
-     * @return array
+     * @return array<string,mixed>
      */
     public function getSourceChildPropertiesToBeConverted($source)
     {
@@ -90,7 +90,7 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return mixed|Error the target type, or an error object if a user-error occurred
      * @api
diff --git a/Neos.Flow/Classes/Property/TypeConverter/ArrayObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/ArrayObjectConverter.php
index ea519af032..24bfc8c087 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/ArrayObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/ArrayObjectConverter.php
@@ -45,9 +45,9 @@ class ArrayObjectConverter extends AbstractTypeConverter
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
-     * @return array
+     * @return array<mixed>
      * @throws InvalidSourceException
      * @api
      */
diff --git a/Neos.Flow/Classes/Property/TypeConverter/BooleanConverter.php b/Neos.Flow/Classes/Property/TypeConverter/BooleanConverter.php
index 460f1b3541..135b17ab15 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/BooleanConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/BooleanConverter.php
@@ -46,7 +46,7 @@ class BooleanConverter extends AbstractTypeConverter
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return boolean
      * @api
diff --git a/Neos.Flow/Classes/Property/TypeConverter/CollectionConverter.php b/Neos.Flow/Classes/Property/TypeConverter/CollectionConverter.php
index 91755c7d9a..6226dc8fcf 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/CollectionConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/CollectionConverter.php
@@ -49,9 +49,9 @@ class CollectionConverter extends AbstractTypeConverter
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
-     * @return ArrayCollection
+     * @return ArrayCollection<string,mixed>
      * @api
      */
     public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
@@ -63,7 +63,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
      * Returns the source, if it is an array, otherwise an empty array.
      *
      * @param mixed $source
-     * @return array
+     * @return array<mixed>
      * @api
      */
     public function getSourceChildPropertiesToBeConverted($source)
diff --git a/Neos.Flow/Classes/Property/TypeConverter/DateTimeConverter.php b/Neos.Flow/Classes/Property/TypeConverter/DateTimeConverter.php
index 8a68a92286..339b3dce97 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/DateTimeConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/DateTimeConverter.php
@@ -92,7 +92,7 @@ class DateTimeConverter extends AbstractTypeConverter
     /**
      * If conversion is possible.
      *
-     * @param string|int|array $source
+     * @param string|int|array<mixed> $source
      * @param string $targetType
      * @return boolean
      */
@@ -101,21 +101,16 @@ public function canConvertFrom($source, $targetType)
         if (!is_callable([$targetType, 'createFromFormat'])) {
             return false;
         }
-        if (is_array($source)) {
-            return true;
-        }
-        if (is_integer($source)) {
-            return true;
-        }
-        return is_string($source);
+
+        return true;
     }
 
     /**
      * Converts $source to a \DateTime using the configured dateFormat
      *
-     * @param string|integer|array $source the string to be converted to a \DateTime object
+     * @param string|integer|array<string,mixed> $source the string to be converted to a \DateTime object
      * @param string $targetType must be "DateTime"
-     * @param array $convertedChildProperties not used currently
+     * @param array<string,mixed> $convertedChildProperties not used currently
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return \DateTimeInterface|null|Error
      * @throws InvalidPropertyMappingConfigurationException
@@ -171,7 +166,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
         if ($date === false) {
             return new Error('The date "%s" was not recognized (for format "%s").', 1307719788, [$dateAsString, $dateFormat]);
         }
-        if (isset($source['hour'], $source['minute'], $source['second']) && is_array($source)) {
+        if (isset($source['hour'], $source['minute'], $source['second'])) {
             $date = $this->overrideTime($date, $source);
         }
         return $date;
@@ -179,7 +174,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
 
     /**
      * Returns whether date information (day, month, year) are present as keys in $source.
-     * @param array $source
+     * @param array<string,mixed> $source
      * @return bool
      */
     protected function isDatePartKeysProvided(array $source)
@@ -215,7 +210,7 @@ protected function getDefaultDateFormat(?PropertyMappingConfigurationInterface $
      * Overrides hour, minute & second of the given date with the values in the $source array
      *
      * @param \DateTimeInterface $date
-     * @param array $source
+     * @param array<string,mixed> $source
      * @return \DateTimeInterface
      */
     protected function overrideTime(\DateTimeInterface $date, array $source)
@@ -223,7 +218,7 @@ protected function overrideTime(\DateTimeInterface $date, array $source)
         $hour = isset($source['hour']) ? (integer)$source['hour'] : 0;
         $minute = isset($source['minute']) ? (integer)$source['minute'] : 0;
         $second = isset($source['second']) ? (integer)$source['second'] : 0;
-        if ($date instanceof \DateTime || $date instanceof \DateTimeImmutable) {
+        if (is_callable([$date, 'setTime'])) {
             $date = $date->setTime($hour, $minute, $second);
         }
         return $date;
diff --git a/Neos.Flow/Classes/Property/TypeConverter/FloatConverter.php b/Neos.Flow/Classes/Property/TypeConverter/FloatConverter.php
index 5cd49c1183..d8919f9e9e 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/FloatConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/FloatConverter.php
@@ -124,7 +124,7 @@ class FloatConverter extends AbstractTypeConverter
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return float|Error|null
      * @throws InvalidPropertyMappingConfigurationException
@@ -172,7 +172,7 @@ protected function parseUsingLocaleIfConfigured($source, PropertyMappingConfigur
         }
 
         if (!$locale instanceof Locale) {
-            $exceptionMessage = 'Determined locale is not of type "\Neos\Flow\I18n\Locale", but of type "' . (is_object($locale) ? get_class($locale) : gettype($locale)) . '".';
+            $exceptionMessage = 'Determined locale is not of type "\Neos\Flow\I18n\Locale", but of type "' . gettype($locale) . '".';
             throw new InvalidPropertyMappingConfigurationException($exceptionMessage, 1334837413);
         }
 
@@ -215,8 +215,8 @@ protected function parseUsingLocaleIfConfigured($source, PropertyMappingConfigur
      * Helper method to collect configuration for this class.
      *
      * @param PropertyMappingConfigurationInterface $configuration
-     * @param array $configurationKeys
-     * @return array
+     * @param array<string> $configurationKeys
+     * @return array<string,mixed>
      */
     protected function getConfigurationKeysAndValues(PropertyMappingConfigurationInterface $configuration, array $configurationKeys)
     {
diff --git a/Neos.Flow/Classes/Property/TypeConverter/IntegerConverter.php b/Neos.Flow/Classes/Property/TypeConverter/IntegerConverter.php
index 6ccf96a562..edecebe380 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/IntegerConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/IntegerConverter.php
@@ -47,7 +47,7 @@ class IntegerConverter extends AbstractTypeConverter
      *
      * @param int|string|\DateTimeInterface|null $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return integer|null|Error
      * @api
diff --git a/Neos.Flow/Classes/Property/TypeConverter/MediaTypeConverter.php b/Neos.Flow/Classes/Property/TypeConverter/MediaTypeConverter.php
index f78b1cd663..96d4f58d31 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/MediaTypeConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/MediaTypeConverter.php
@@ -48,9 +48,9 @@ class MediaTypeConverter extends AbstractTypeConverter implements MediaTypeConve
      *
      * @param string $source the raw request body
      * @param string $targetType must be "array"
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
-     * @return array|string|integer Note that this TypeConverter may return a non-array in case of JSON media type, even though he declares to only convert to array
+     * @return array<mixed>|string|integer Note that this TypeConverter may return a non-array in case of JSON media type, even though he declares to only convert to array
      * @api
      */
     public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
@@ -71,13 +71,13 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
      *
      * @param string $requestBody the raw request body
      * @param string $mediaType the configured media type (for example "application/json")
-     * @return array|string|integer
+     * @return array<mixed>|string|integer
      * @api
      */
     protected function convertMediaType($requestBody, $mediaType)
     {
         $mediaTypeParts = MediaTypes::parseMediaType($mediaType);
-        if (!isset($mediaTypeParts['subtype']) || $mediaTypeParts['subtype'] === '') {
+        if ($mediaTypeParts['subtype'] === '') {
             return [];
         }
         $result = [];
diff --git a/Neos.Flow/Classes/Property/TypeConverter/ObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/ObjectConverter.php
index 62f6599243..77a33e5657 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/ObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/ObjectConverter.php
@@ -79,7 +79,18 @@ class ObjectConverter extends AbstractTypeConverter
     /**
      * As it is very likely that the constructor arguments are needed twice we should cache them for the request.
      *
-     * @var array
+     * @var array<class-string,array<string,array{
+     *       position: int,
+     *       optional: bool,
+     *       type: ?string,
+     *       class: ?string,
+     *       array: bool,
+     *       byReference: bool,
+     *       allowsNull: bool,
+     *       defaultValue: mixed,
+     *       scalarDeclaration: bool,
+     *       annotations: array<string,array<int,object>>,
+     *  }>>
      */
     protected $constructorReflectionFirstLevelCache = [];
 
@@ -93,9 +104,12 @@ class ObjectConverter extends AbstractTypeConverter
     public function canConvertFrom($source, $targetType)
     {
         return !(
-            $this->reflectionService->isClassAnnotatedWith($targetType, Flow\Entity::class) ||
-            $this->reflectionService->isClassAnnotatedWith($targetType, Flow\ValueObject::class) ||
-            $this->reflectionService->isClassAnnotatedWith($targetType, \Doctrine\ORM\Mapping\Entity::class)
+            class_exists($targetType) &&
+            (
+                $this->reflectionService->isClassAnnotatedWith($targetType, Flow\Entity::class) ||
+                $this->reflectionService->isClassAnnotatedWith($targetType, Flow\ValueObject::class) ||
+                $this->reflectionService->isClassAnnotatedWith($targetType, \Doctrine\ORM\Mapping\Entity::class)
+            )
         );
     }
 
@@ -116,7 +130,7 @@ public function getSourceChildPropertiesToBeConverted($source)
     /**
      * The type of a property is determined by the reflection service.
      *
-     * @param string $targetType
+     * @param class-string $targetType
      * @param string $propertyName
      * @param PropertyMappingConfigurationInterface $configuration
      * @return string|null
@@ -149,6 +163,9 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
                     // would not find a property mapper. It is needed because the ObjectConverter doesn't use class schemata,
                     // but reads the annotations directly.
                     $declaredType = strtok(trim(current($varTagValues), " \n\t"), " \n\t");
+                    if ($declaredType === false) {
+                        throw new \Exception('Invalid declared type', 1744058940);
+                    }
                     try {
                         $parsedType = TypeHandling::parseType($declaredType);
                     } catch (InvalidTypeException $exception) {
@@ -173,7 +190,7 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return object the target type
      * @throws InvalidTargetException
@@ -185,6 +202,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
         $object = $this->buildObject($convertedChildProperties, $targetType);
         foreach ($convertedChildProperties as $propertyName => $propertyValue) {
             $result = ObjectAccess::setProperty($object, $propertyName, $propertyValue);
+            /** @var object $object */
             if ($result === false) {
                 $exceptionMessage = sprintf(
                     'Property "%s" having a value of type "%s" could not be set in target object of type "%s". Make sure that the property is accessible properly, for example via an appropriate setter method.',
@@ -214,7 +232,7 @@ public function getTargetTypeForSource($source, $originalTargetType, ?PropertyMa
     {
         $targetType = $originalTargetType;
 
-        if (is_array($source) && array_key_exists('__type', $source)) {
+        if (is_array($source) && array_key_exists('__type', $source) && is_string($source['__type'])) {
             $targetType = $source['__type'];
 
             if ($configuration === null) {
@@ -224,6 +242,7 @@ public function getTargetTypeForSource($source, $originalTargetType, ?PropertyMa
                 throw new InvalidPropertyMappingConfigurationException('Override of target type not allowed. To enable this, you need to set the PropertyMappingConfiguration Value "CONFIGURATION_OVERRIDE_TARGET_TYPE_ALLOWED" to true.', 1317050430);
             }
 
+            /** @todo is_a is not recursive! replace with is_subclass_of or similar */
             if ($targetType !== $originalTargetType && is_a($targetType, $originalTargetType, true) === false) {
                 throw new InvalidDataTypeException('The given type "' . $targetType . '" is not a subtype of "' . $originalTargetType . '".', 1317048056);
             }
@@ -239,7 +258,7 @@ public function getTargetTypeForSource($source, $originalTargetType, ?PropertyMa
      *
      * Furthermore, the constructor arguments are removed from $possibleConstructorArgumentValues
      *
-     * @param array &$possibleConstructorArgumentValues
+     * @param array<string,mixed> &$possibleConstructorArgumentValues
      * @param string $objectType
      * @return object The created instance
      * @throws InvalidTargetException if a required constructor argument is missing
@@ -248,6 +267,9 @@ protected function buildObject(array &$possibleConstructorArgumentValues, $objec
     {
         $constructorArguments = [];
         $className = $this->objectManager->getClassNameByObjectName($objectType);
+        if ($className === false) {
+            throw new \Exception('Invalid object type '. $objectType, 1744058576);
+        }
         $constructorSignature = $this->getConstructorArgumentsForClass($className);
         if (count($constructorSignature)) {
             foreach ($constructorSignature as $constructorArgumentName => $constructorArgumentReflection) {
@@ -256,7 +278,7 @@ protected function buildObject(array &$possibleConstructorArgumentValues, $objec
                     unset($possibleConstructorArgumentValues[$constructorArgumentName]);
                 } elseif ($constructorArgumentReflection['optional'] === true) {
                     $constructorArguments[] = $constructorArgumentReflection['defaultValue'];
-                } elseif ($this->objectManager->isRegistered($constructorArgumentReflection['type']) && $this->objectManager->getScope($constructorArgumentReflection['type']) === Configuration::SCOPE_SINGLETON) {
+                } elseif ($constructorArgumentReflection['type'] && $this->objectManager->isRegistered($constructorArgumentReflection['type']) && $this->objectManager->getScope($constructorArgumentReflection['type']) === Configuration::SCOPE_SINGLETON) {
                     $constructorArguments[] = $this->objectManager->get($constructorArgumentReflection['type']);
                 } else {
                     throw new InvalidTargetException('Missing constructor argument "' . $constructorArgumentName . '" for object of type "' . $objectType . '".', 1268734872);
@@ -272,8 +294,19 @@ protected function buildObject(array &$possibleConstructorArgumentValues, $objec
     /**
      * Get the constructor argument reflection for the given object type.
      *
-     * @param string $className
-     * @return array<array>
+     * @param class-string $className
+     * @return array<string,array{
+     *        position: int,
+     *        optional: bool,
+     *        type: ?string,
+     *        class: ?string,
+     *        array: bool,
+     *        byReference: bool,
+     *        allowsNull: bool,
+     *        defaultValue: mixed,
+     *        scalarDeclaration: bool,
+     *        annotations: array<string,array<int,object>>,
+     * }>
      */
     protected function getConstructorArgumentsForClass($className)
     {
diff --git a/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectConverter.php
index 9ce89473ea..8f4bd51253 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectConverter.php
@@ -88,9 +88,12 @@ class PersistentObjectConverter extends ObjectConverter
     public function canConvertFrom($source, $targetType)
     {
         return (
-            $this->reflectionService->isClassAnnotatedWith($targetType, Flow\Entity::class) ||
-            $this->reflectionService->isClassAnnotatedWith($targetType, ValueObject::class) ||
-            $this->reflectionService->isClassAnnotatedWith($targetType, \Doctrine\ORM\Mapping\Entity::class)
+            class_exists($targetType) &&
+            (
+                $this->reflectionService->isClassAnnotatedWith($targetType, Flow\Entity::class) ||
+                $this->reflectionService->isClassAnnotatedWith($targetType, ValueObject::class) ||
+                $this->reflectionService->isClassAnnotatedWith($targetType, \Doctrine\ORM\Mapping\Entity::class)
+            )
         );
     }
 
@@ -114,7 +117,7 @@ public function getSourceChildPropertiesToBeConverted($source)
     /**
      * The type of a property is determined by the reflection service.
      *
-     * @param string $targetType
+     * @param class-string $targetType
      * @param string $propertyName
      * @param PropertyMappingConfigurationInterface $configuration
      * @return string
@@ -128,6 +131,9 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
         }
 
         $schema = $this->reflectionService->getClassSchema($targetType);
+        if (!$schema) {
+            throw new InvalidTargetException('Schema for target object of type "' . $targetType . '" not found.', 1744057928);
+        }
         $setterMethodName = ObjectAccess::buildSetterMethodName($propertyName);
         $constructorParameters = $this->reflectionService->getMethodParameters($targetType, '__construct');
 
@@ -154,7 +160,7 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface $configuration
      * @return object|TargetNotFoundError|null the converted entity/value object or an instance of TargetNotFoundError if the object could not be resolved
      * @throws \InvalidArgumentException|InvalidTargetException
@@ -191,6 +197,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
 
         foreach ($convertedChildProperties as $propertyName => $propertyValue) {
             // We need to check for "immutable" constructor arguments that have no setter and remove them.
+            /** @var object $object */
             if (isset($objectConstructorArguments[$propertyName]) && !ObjectAccess::isPropertySettable($object, $propertyName)) {
                 $currentPropertyValue = ObjectAccess::getProperty($object, $propertyName);
                 if ($currentPropertyValue === $propertyValue) {
@@ -217,15 +224,16 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
             }
         }
 
+        /** @var object $object */
         return $object;
     }
 
     /**
      * Handle the case if $source is an array.
      *
-     * @param array $source
+     * @param array<mixed> $source
      * @param class-string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> &$convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return object|TargetNotFoundError
      * @throws InvalidPropertyMappingConfigurationException
@@ -267,7 +275,7 @@ protected function handleArrayData(array $source, $targetType, array &$converted
      * Set the given $identity on the created $object.
      *
      * @param object $object
-     * @param string|array $identity
+     * @param string|array<mixed> $identity
      * @return void
      * @todo set identity properly if it is composite or custom property
      */
@@ -300,8 +308,8 @@ protected function fetchObjectFromPersistence($identity, $targetType)
     /**
      * Finds an object from the repository by searching for its identity properties.
      *
-     * @param array $identityProperties Property names and values to search for
-     * @param string $type The object type to look for
+     * @param array<string,mixed> $identityProperties Property names and values to search for
+     * @param class-string $type The object type to look for
      * @return object|null Either the object matching the identity or NULL if no object was found
      * @throws DuplicateObjectException if more than one object was found
      */
@@ -311,7 +319,7 @@ protected function findObjectByIdentityProperties(array $identityProperties, $ty
         $classSchema = $this->reflectionService->getClassSchema($type);
 
         $equals = [];
-        foreach ($classSchema->getIdentityProperties() as $propertyName => $propertyType) {
+        foreach ($classSchema?->getIdentityProperties() ?: [] as $propertyName => $propertyType) {
             if (isset($identityProperties[$propertyName])) {
                 if ($propertyType === 'string') {
                     $equals[] = $query->equals($propertyName, $identityProperties[$propertyName], false);
diff --git a/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectSerializer.php b/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectSerializer.php
index 5231260403..0ee57cbfde 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectSerializer.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/PersistentObjectSerializer.php
@@ -52,7 +52,7 @@ class PersistentObjectSerializer extends AbstractTypeConverter
      *
      * @param object $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return mixed The identifier for the object if it is known, or NULL
      */
diff --git a/Neos.Flow/Classes/Property/TypeConverter/ScalarTypeToObjectConverter.php b/Neos.Flow/Classes/Property/TypeConverter/ScalarTypeToObjectConverter.php
index 988e0a5ad4..4656aa035f 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/ScalarTypeToObjectConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/ScalarTypeToObjectConverter.php
@@ -58,6 +58,9 @@ class ScalarTypeToObjectConverter extends AbstractTypeConverter
      */
     public function canConvertFrom($source, $targetType)
     {
+        if (!class_exists($targetType)) {
+            return false;
+        }
         if ((
             $this->reflectionService->isClassAnnotatedWith($targetType, Flow\Entity::class) ||
             $this->reflectionService->isClassAnnotatedWith($targetType, Flow\ValueObject::class) ||
@@ -71,7 +74,8 @@ public function canConvertFrom($source, $targetType)
             return false;
         }
         $methodParameter = array_shift($methodParameters);
-        return TypeHandling::normalizeType($methodParameter['type']) === TypeHandling::normalizeType(gettype($source));
+        $methodParameterType = $methodParameter['type'] ?? null;
+        return ($methodParameterType ? TypeHandling::normalizeType($methodParameterType) : null) === TypeHandling::normalizeType(gettype($source));
     }
 
     /**
@@ -79,7 +83,7 @@ public function canConvertFrom($source, $targetType)
      *
      * @param string|float|integer|bool $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return object
      */
diff --git a/Neos.Flow/Classes/Property/TypeConverter/SessionConverter.php b/Neos.Flow/Classes/Property/TypeConverter/SessionConverter.php
index 3729434ed9..72ab19178b 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/SessionConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/SessionConverter.php
@@ -14,6 +14,7 @@
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\Property\PropertyMappingConfigurationInterface;
 use Neos\Flow\Session\Session;
+use Neos\Flow\Session\SessionInterface;
 use Neos\Flow\Session\SessionManagerInterface;
 
 /**
@@ -70,9 +71,9 @@ public function canConvertFrom($source, $targetType)
      *
      * @param string $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
-     * @return object the target type
+     * @return ?SessionInterface the target type
      */
     public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
     {
diff --git a/Neos.Flow/Classes/Property/TypeConverter/StringConverter.php b/Neos.Flow/Classes/Property/TypeConverter/StringConverter.php
index dce5764954..ee58bc43ab 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/StringConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/StringConverter.php
@@ -94,7 +94,7 @@ class StringConverter extends AbstractTypeConverter
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return string
      * @throws InvalidPropertyMappingConfigurationException
@@ -113,7 +113,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
                 case self::ARRAY_FORMAT_CSV:
                     return implode($this->getCsvDelimiter($configuration), $source);
                 case self::ARRAY_FORMAT_JSON:
-                    return json_encode($source);
+                    return json_encode($source, JSON_THROW_ON_ERROR);
                 default:
                     throw new InvalidPropertyMappingConfigurationException(sprintf('Invalid array export format "%s" given', $this->getArrayFormat($configuration)), 1404317220);
             }
diff --git a/Neos.Flow/Classes/Property/TypeConverter/TypedArrayConverter.php b/Neos.Flow/Classes/Property/TypeConverter/TypedArrayConverter.php
index f183ca93cf..5550c4b281 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/TypedArrayConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/TypedArrayConverter.php
@@ -56,11 +56,11 @@ public function canConvertFrom($source, $targetType)
     }
 
     /**
-     * @param array $source An array of objects/simple types
+     * @param array<mixed> $source An array of objects/simple types
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
-     * @return array
+     * @return array<string,mixed>
      * @api
      */
     public function convertFrom($source, $targetType, array $convertedChildProperties = [], ?PropertyMappingConfigurationInterface $configuration = null)
@@ -72,7 +72,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
      * Returns the source, if it is an array, otherwise an empty array.
      *
      * @param mixed $source
-     * @return array
+     * @return array<mixed>
      */
     public function getSourceChildPropertiesToBeConverted($source)
     {
@@ -85,7 +85,7 @@ public function getSourceChildPropertiesToBeConverted($source)
      * @param string $targetType
      * @param string $propertyName
      * @param PropertyMappingConfigurationInterface $configuration
-     * @return string
+     * @return ?string
      */
     public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappingConfigurationInterface $configuration)
     {
diff --git a/Neos.Flow/Classes/Property/TypeConverter/UriTypeConverter.php b/Neos.Flow/Classes/Property/TypeConverter/UriTypeConverter.php
index f8556886df..3a6299e3c2 100644
--- a/Neos.Flow/Classes/Property/TypeConverter/UriTypeConverter.php
+++ b/Neos.Flow/Classes/Property/TypeConverter/UriTypeConverter.php
@@ -46,7 +46,7 @@ class UriTypeConverter extends AbstractTypeConverter
      *
      * @param string $source The URI to be converted
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return Uri|Error if the input format is not supported or could not be converted for other reasons
      */
diff --git a/Neos.Flow/Classes/Property/TypeConverterInterface.php b/Neos.Flow/Classes/Property/TypeConverterInterface.php
index d9bb5bbc8e..47c0e0b561 100644
--- a/Neos.Flow/Classes/Property/TypeConverterInterface.php
+++ b/Neos.Flow/Classes/Property/TypeConverterInterface.php
@@ -104,7 +104,7 @@ public function getTypeOfChildProperty($targetType, $propertyName, PropertyMappi
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<string,mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return mixed|Error the target type, or an error object if a user-error occurred
      * @throws Exception\TypeConverterException thrown in case a developer error occurred
diff --git a/Neos.Flow/Classes/Reflection/ClassReflection.php b/Neos.Flow/Classes/Reflection/ClassReflection.php
index 34664fab6c..6ecc334ca4 100644
--- a/Neos.Flow/Classes/Reflection/ClassReflection.php
+++ b/Neos.Flow/Classes/Reflection/ClassReflection.php
@@ -16,6 +16,7 @@
 /**
  * Extended version of the ReflectionClass
  *
+ * @extends \ReflectionClass<object>
  * @Flow\Proxy(false)
  */
 class ClassReflection extends \ReflectionClass
@@ -39,7 +40,7 @@ static function ($className) use ($classNameOrObject) {
     }
 
     /**
-     * @var DocCommentParser Holds an instance of the doc comment parser for this class
+     * @var ?DocCommentParser Holds an instance of the doc comment parser for this class
      */
     protected $docCommentParser;
 
@@ -48,12 +49,14 @@ static function ($className) use ($classNameOrObject) {
      * that MethodReflection objects are returned instead of the
      * original ReflectionMethod instances.
      *
-     * @return MethodReflection Method reflection object of the constructor method
+     * @return ?MethodReflection Method reflection object of the constructor method
      */
-    public function getConstructor(): MethodReflection
+    public function getConstructor(): ?MethodReflection
     {
         $parentConstructor = parent::getConstructor();
-        return (!is_object($parentConstructor)) ? $parentConstructor : new MethodReflection($this->getName(), $parentConstructor->getName());
+        return $parentConstructor === null
+            ? $parentConstructor
+            : new MethodReflection($this->getName(), $parentConstructor->getName());
     }
 
     /**
@@ -165,7 +168,7 @@ public function isTaggedWith($tag)
     /**
      * Returns an array of tags and their values
      *
-     * @return array Tags and values
+     * @return array<string,array<int,string>> Tags and values
      */
     public function getTagsValues()
     {
@@ -175,7 +178,7 @@ public function getTagsValues()
     /**
      * Returns the values of the specified tag
      * @param string $tag
-     * @return array Values of the given tag
+     * @return array<int,string> Values of the given tag
      */
     public function getTagValues($tag)
     {
@@ -205,7 +208,7 @@ public function newInstanceWithoutConstructor(): object
     {
         $instance = parent::newInstanceWithoutConstructor();
 
-        if (method_exists($instance, '__wakeup') && is_callable([$instance, '__wakeup'])) {
+        if (method_exists($instance, '__wakeup')) {
             $instance->__wakeup();
         }
 
@@ -221,8 +224,11 @@ public function newInstanceWithoutConstructor(): object
     protected function getDocCommentParser()
     {
         if (!is_object($this->docCommentParser)) {
-            $this->docCommentParser = new DocCommentParser;
-            $this->docCommentParser->parseDocComment($this->getDocComment());
+            $this->docCommentParser = new DocCommentParser();
+            $docComment = $this->getDocComment();
+            if ($docComment) {
+                $this->docCommentParser->parseDocComment($docComment);
+            }
         }
         return $this->docCommentParser;
     }
diff --git a/Neos.Flow/Classes/Reflection/ClassSchema.php b/Neos.Flow/Classes/Reflection/ClassSchema.php
index df24913f7a..98bd7312aa 100644
--- a/Neos.Flow/Classes/Reflection/ClassSchema.php
+++ b/Neos.Flow/Classes/Reflection/ClassSchema.php
@@ -11,6 +11,7 @@
  * source code.
  */
 
+use Neos\Flow\Persistence\RepositoryInterface;
 use Neos\Utility\Exception\InvalidTypeException;
 use Neos\Utility\TypeHandling;
 
@@ -47,21 +48,27 @@ class ClassSchema
     protected $lazyLoadable = false;
 
     /**
-     * @var string|null
+     * @var class-string<RepositoryInterface>|null
      */
     protected $repositoryClassName;
 
     /**
      * Properties of the class which need to be persisted
      *
-     * @var array
+     * @var array<string,array{
+     *     type: string,
+     *     elementType: ?string,
+     *     nullable: bool,
+     *     lazy: bool,
+     *     transient: bool,
+     * }>
      */
     protected $properties = [];
 
     /**
      * The properties forming the identity of an object
      *
-     * @var array
+     * @var array<string,string>
      */
     protected $identityProperties = [];
 
@@ -137,7 +144,13 @@ public function addProperty($name, $type, $lazy = false, $transient = false)
      * hasProperty($propertyName) before!
      *
      * @param string $propertyName
-     * @return array
+     * @return array{
+     *       type: string,
+     *       elementType: ?string,
+     *       nullable: bool,
+     *       lazy: bool,
+     *       transient: bool,
+     * }
      */
     public function getProperty($propertyName)
     {
@@ -147,7 +160,13 @@ public function getProperty($propertyName)
     /**
      * Returns all properties defined in this schema
      *
-     * @return array
+     * @return array<string,array{
+     *      type: string,
+     *      elementType: ?string,
+     *      nullable: bool,
+     *      lazy: bool,
+     *      transient: bool,
+     * }>
      */
     public function getProperties()
     {
@@ -198,7 +217,7 @@ public function getModelType()
     /**
      * Set the class name of the repository managing an entity.
      *
-     * @param string $repositoryClassName
+     * @param ?class-string<RepositoryInterface> $repositoryClassName
      * @return void
      * @throws Exception\ClassSchemaConstraintViolationException
      */
@@ -211,7 +230,7 @@ public function setRepositoryClassName($repositoryClassName)
     }
 
     /**
-     * @return string
+     * @return ?class-string<RepositoryInterface>
      */
     public function getRepositoryClassName()
     {
@@ -300,7 +319,7 @@ public function markAsIdentityProperty($propertyName)
     /**
      * Gets the properties (names and types) forming the identity of an object.
      *
-     * @return array
+     * @return array<string,string>
      * @see markAsIdentityProperty()
      */
     public function getIdentityProperties()
diff --git a/Neos.Flow/Classes/Reflection/DocCommentParser.php b/Neos.Flow/Classes/Reflection/DocCommentParser.php
index 514a976456..3eca9e1db4 100644
--- a/Neos.Flow/Classes/Reflection/DocCommentParser.php
+++ b/Neos.Flow/Classes/Reflection/DocCommentParser.php
@@ -28,7 +28,7 @@ class DocCommentParser
 
     /**
      * An array of tag names and their values (multiple values are possible)
-     * @var array
+     * @var array<string,array<int,string>>
      */
     protected $tags = [];
 
@@ -47,9 +47,9 @@ public function parseDocComment($docComment)
 
         $lines = explode(chr(10), $docComment);
         foreach ($lines as $line) {
-            $line = trim(preg_replace('/\*\/$/', '', $line));
+            $line = trim(preg_replace('/\*\/$/', '', $line) ?: '');
             if ($line !== '' && strpos($line, '* @') !== false) {
-                $this->parseTag(substr($line, strpos($line, '@')));
+                $this->parseTag(substr($line, strpos($line, '@') ?: 0));
             } elseif (count($this->tags) === 0) {
                 $this->description .= preg_replace('/\s*\\/?[\\\\*]*\s?(.*)$/', '$1', $line) . chr(10);
             }
@@ -60,7 +60,7 @@ public function parseDocComment($docComment)
     /**
      * Returns the tags which have been previously parsed
      *
-     * @return array Array of tag names and their (multiple) values
+     * @return array<string,array<int,string>> Array of tag names and their (multiple) values
      */
     public function getTagsValues()
     {
@@ -73,7 +73,7 @@ public function getTagsValues()
      * available.
      *
      * @param string $tagName The tag name to retrieve the values for
-     * @return array The tag's values
+     * @return array<int,string> The tag's values
      * @throws Exception
      */
     public function getTagValues($tagName)
@@ -116,7 +116,7 @@ protected function parseTag($line)
     {
         $tagAndValue = [];
         if (preg_match('/@[A-Za-z0-9\\\\]+\\\\([A-Za-z0-9]+)(?:\\((.*)\\))?$/', $line, $tagAndValue) === 0) {
-            $tagAndValue = preg_split('/\s/', $line, 2);
+            $tagAndValue = preg_split('/\s/', $line, 2) ?: [];
         } else {
             array_shift($tagAndValue);
         }
diff --git a/Neos.Flow/Classes/Reflection/MethodReflection.php b/Neos.Flow/Classes/Reflection/MethodReflection.php
index b5e8a0e1e7..37b4317881 100644
--- a/Neos.Flow/Classes/Reflection/MethodReflection.php
+++ b/Neos.Flow/Classes/Reflection/MethodReflection.php
@@ -21,7 +21,7 @@
 class MethodReflection extends \ReflectionMethod
 {
     /**
-     * @var DocCommentParser An instance of the doc comment parser
+     * @var ?DocCommentParser An instance of the doc comment parser
      */
     protected $docCommentParser;
 
@@ -66,7 +66,7 @@ public function isTaggedWith($tag)
     /**
      * Returns an array of tags and their values
      *
-     * @return array Tags and values
+     * @return array<string,array<int,string>> Tags and values
      */
     public function getTagsValues()
     {
@@ -77,7 +77,7 @@ public function getTagsValues()
      * Returns the values of the specified tag
      *
      * @param string $tag Tag name to check for
-     * @return array Values of the given tag
+     * @return array<int,string> Values of the given tag
      */
     public function getTagValues($tag)
     {
@@ -99,9 +99,6 @@ public function getDescription()
      */
     public function getDeclaredReturnType()
     {
-        if (!is_callable([$this, 'getReturnType'])) {
-            return null;
-        }
         $type = $this->getReturnType();
         return $type !== null ? ltrim((string)$type, '?') : null;
     }
@@ -111,9 +108,6 @@ public function getDeclaredReturnType()
      */
     public function isDeclaredReturnTypeNullable()
     {
-        if (!is_callable([$this, 'getReturnType'])) {
-            return false;
-        }
         $type = $this->getReturnType();
         return $type !== null && $type->allowsNull();
     }
@@ -127,8 +121,11 @@ public function isDeclaredReturnTypeNullable()
     protected function getDocCommentParser()
     {
         if (!is_object($this->docCommentParser)) {
-            $this->docCommentParser = new DocCommentParser;
-            $this->docCommentParser->parseDocComment($this->getDocComment());
+            $this->docCommentParser = new DocCommentParser();
+            $docComment = $this->getDocComment();
+            if ($docComment) {
+                $this->docCommentParser->parseDocComment($docComment);
+            }
         }
         return $this->docCommentParser;
     }
diff --git a/Neos.Flow/Classes/Reflection/ParameterReflection.php b/Neos.Flow/Classes/Reflection/ParameterReflection.php
index 94c560aac0..11d4831436 100644
--- a/Neos.Flow/Classes/Reflection/ParameterReflection.php
+++ b/Neos.Flow/Classes/Reflection/ParameterReflection.php
@@ -28,11 +28,12 @@ class ParameterReflection extends \ReflectionParameter
     /**
      * Returns the declaring class
      *
-     * @return ClassReflection The declaring class
+     * @return ?ClassReflection The declaring class
      */
-    public function getDeclaringClass(): ClassReflection
+    public function getDeclaringClass(): ?ClassReflection
     {
-        return new ClassReflection(parent::getDeclaringClass()->getName());
+        $reflectionClass = parent::getDeclaringClass();
+        return $reflectionClass ? new ClassReflection($reflectionClass->getName()) : null;
     }
 
     /**
diff --git a/Neos.Flow/Classes/Reflection/PropertyReflection.php b/Neos.Flow/Classes/Reflection/PropertyReflection.php
index 1b59ba4c4e..4afc83c6f8 100644
--- a/Neos.Flow/Classes/Reflection/PropertyReflection.php
+++ b/Neos.Flow/Classes/Reflection/PropertyReflection.php
@@ -21,7 +21,7 @@
 class PropertyReflection extends \ReflectionProperty
 {
     /**
-     * @var DocCommentParser An instance of the doc comment parser
+     * @var ?DocCommentParser An instance of the doc comment parser
      */
     protected $docCommentParser;
 
@@ -58,7 +58,7 @@ public function getDeclaringClass(): ClassReflection
     /**
      * Returns an array of tags and their values
      *
-     * @return array Tags and values
+     * @return array<string,array<int,string>> Tags and values
      */
     public function getTagsValues()
     {
@@ -69,7 +69,7 @@ public function getTagsValues()
      * Returns the values of the specified tag
      *
      * @param string $tag
-     * @return array Values of the given tag
+     * @return array<int,string> Values of the given tag
      */
     public function getTagValues($tag)
     {
@@ -137,8 +137,11 @@ public function setValue($object = null, $value = null): void
     protected function getDocCommentParser()
     {
         if (!is_object($this->docCommentParser)) {
-            $this->docCommentParser = new DocCommentParser;
-            $this->docCommentParser->parseDocComment($this->getDocComment());
+            $this->docCommentParser = new DocCommentParser();
+            $docComment = $this->getDocComment();
+            if ($docComment) {
+                $this->docCommentParser->parseDocComment($docComment);
+            }
         }
         return $this->docCommentParser;
     }
diff --git a/Neos.Flow/Classes/Reflection/ReflectionService.php b/Neos.Flow/Classes/Reflection/ReflectionService.php
index 5c720b5db0..f9d457c48f 100644
--- a/Neos.Flow/Classes/Reflection/ReflectionService.php
+++ b/Neos.Flow/Classes/Reflection/ReflectionService.php
@@ -92,6 +92,9 @@ class ReflectionService
     protected const DATA_PARAMETER_ANNOTATIONS = 25;
 
     protected Reader $annotationReader;
+    /**
+     * @var array<string,array<class-string>> class names per package (key)
+     */
     protected array $availableClassNames = [];
     protected VariableFrontend $reflectionDataRuntimeCache;
     protected VariableFrontend $classSchemataRuntimeCache;
@@ -107,40 +110,87 @@ class ReflectionService
     /**
      * a cache which stores the use statements reflected for a particular class
      * (only relevant for un-expanded "var" and "param" annotations)
+     *
+     * @var array<class-string,array<string>>
      */
     protected array $useStatementsForClassCache;
 
+    /**
+     * @var array<string,mixed>
+     */
     protected array $settings = [];
 
     /**
      * Array of annotation classnames and the names of classes which are annotated with them
+     *
+     * @var array<class-string,array<class-string, bool>>
      */
     protected array $annotatedClasses = [];
 
     /**
      * Array of method annotations and the classes and methods which are annotated with them
+     *
+     * @var array<class-string,array<class-string,array<string,string>>>
      */
     protected array $classesByMethodAnnotations = [];
 
     /**
      * Schemata of all classes which can be persisted
      *
-     * @var array<string, ClassSchema|false>
+     * @var array<class-string,ClassSchema>
      */
     protected array $classSchemata = [];
 
     /**
      * An array of class names which are currently being forgotten by forgetClass(). Acts as a safeguard against infinite loops.
+     *
+     * @var array<class-string,true>
      */
     protected array $classesCurrentlyBeingForgotten = [];
 
     /**
      * Array with reflection information indexed by class name
+     *
+     * @var array<class-string,array{
+     *     1?: array<class-string,bool>,
+     *     3?: array<class-string,bool>,
+     *     5?: array<int,object>,
+     *     6?: true,
+     *     7?: true,
+     *     8?: array<string,array{
+     *         10?: true,
+     *         11?: true,
+     *         12: int,
+     *         13: array<string,array{
+     *             16: int,
+     *             17?: true,
+     *             18?: string,
+     *             19?: true,
+     *             20?: string,
+     *             21?: true,
+     *             22?: mixed,
+     *             23?: true,
+     *             24?: true,
+     *             25?: array<string,array<int,object>>
+     *         }>,
+     *         25: ?string
+     *     }>,
+     *     9?: array<string,array{
+     *         14?: array<int|string,array<mixed>>,
+     *         15?: array<string,array<int,object>>,
+     *         24?: int,
+     *         26?: string,
+     *         28?: true,
+     *     }>,
+     *     27?: true,
+     * }|false>
      */
     protected array $classReflectionData = [];
 
     /**
      * Array with updated reflection information (e.g. in Development context after classes have changed)
+     *
+     * @var array<class-string,true>
      */
     protected array $updatedReflectionData = [];
 
@@ -148,6 +198,8 @@ class ReflectionService
 
     /**
      * A runtime cache for reflected method annotations to speed up repeating checks.
+     *
+     * @var array<class-string,array<string,array<object>>>
      */
     protected array $methodAnnotationsRuntimeCache = [];
 
@@ -162,6 +214,9 @@ public function setClassSchemataRuntimeCache(VariableFrontend $cache): void
         $this->classSchemataRuntimeCache = $cache;
     }
 
+    /**
+     * @param array<string,mixed> $settings
+     */
     public function injectSettings(array $settings): void
     {
         $this->settings = $settings['reflection'];
@@ -211,7 +266,7 @@ protected function initialize(): void
      * This method is called by the Compile Time Object Manager which also determines
      * the list of classes to consider for reflection.
      *
-     * @param array $availableClassNames
+     * @param array<string,array<int,class-string>> $availableClassNames
      * @throws ClassLoadingForReflectionFailedException
      * @throws ClassSchemaConstraintViolationException
      * @throws Exception
@@ -251,6 +306,7 @@ public function isClassReflected(string $className): bool
     /**
      * Returns the names of all classes known to this reflection service.
      *
+     * @return array<int,class-string>
      * @api
      */
     public function getAllClassNames(): array
@@ -268,19 +324,20 @@ public function getAllClassNames(): array
      * implementation was found in the package defining the interface, false is returned.
      *
      * @param class-string $interfaceName
-     * @return string|bool
+     * @return class-string|false
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
      * @api
      */
-    public function getDefaultImplementationClassNameForInterface(string $interfaceName): string|bool
+    public function getDefaultImplementationClassNameForInterface(string $interfaceName): string|false
     {
         if (interface_exists($interfaceName) === false) {
             throw new \InvalidArgumentException('"' . $interfaceName . '" does not exist or is not the name of an interface.', 1238769559);
         }
         $interfaceName = $this->prepareClassReflectionForUsage($interfaceName);
 
+        /** @var array<class-string> $classNamesFound */
         $classNamesFound = array_keys($this->classReflectionData[$interfaceName][self::DATA_INTERFACE_IMPLEMENTATIONS] ?? []);
         if (count($classNamesFound) === 1) {
             return $classNamesFound[0];
@@ -318,6 +375,7 @@ public function getAllImplementationClassNamesForInterface(string $interfaceName
         }
         $interfaceName = $this->prepareClassReflectionForUsage($interfaceName);
 
+        /** @phpstan-ignore return.type (classic subtype dilemma; don't know how to solve it yet) */
         return array_keys($this->classReflectionData[$interfaceName][self::DATA_INTERFACE_IMPLEMENTATIONS] ?? []);
     }
 
@@ -325,8 +383,9 @@ public function getAllImplementationClassNamesForInterface(string $interfaceName
      * Searches for and returns all names of classes inheriting the specified class.
      * If no class inheriting the given class was found, an empty array is returned.
      *
-     * @param class-string $className
-     * @return array<class-string>
+     * @template T of object
+     * @param class-string<T> $className
+     * @return array<class-string<T>>
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -338,12 +397,16 @@ public function getAllSubClassNamesForClass(string $className): array
             throw new \InvalidArgumentException('"' . $className . '" does not exist or is not the name of a class.', 1257168042);
         }
         $className = $this->prepareClassReflectionForUsage($className);
+        /** @phpstan-ignore return.type (classic subtype dilemma; don't know how to solve it yet) */
         return array_keys($this->classReflectionData[$className][self::DATA_CLASS_SUBCLASSES] ?? []);
     }
 
     /**
      * Searches for and returns all names of classes which are tagged by the specified
      * annotation. If no classes were found, an empty array is returned.
+     *
+     * @param class-string $annotationClassName
+     * @return array<int,class-string>
      */
     public function getClassNamesByAnnotation(string $annotationClassName): array
     {
@@ -358,6 +421,8 @@ public function getClassNamesByAnnotation(string $annotationClassName): array
     /**
      * Tells if the specified class has the given annotation
      *
+     * @param class-string $className
+     * @param class-string $annotationClassName
      * @api
      */
     public function isClassAnnotatedWith(string $className, string $annotationClassName): bool
@@ -375,9 +440,10 @@ public function isClassAnnotatedWith(string $className, string $annotationClassN
     /**
      * Returns the specified class annotations or an empty array
      *
+     * @template T
      * @param class-string $className
-     * @param null|class-string $annotationClassName
-     * @return array<object>
+     * @param null|class-string<T> $annotationClassName
+     * @return ($annotationClassName is null ? array<int,object> : array<int,T>)
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -410,9 +476,10 @@ public function getClassAnnotations(string $className, string|null $annotationCl
      * If multiple annotations are set on the target you will
      * get the first instance of them.
      *
+     * @template T of object
      * @param class-string $className
-     * @param class-string $annotationClassName
-     * @return object|null
+     * @param class-string<T> $annotationClassName
+     * @return T|null
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -424,12 +491,15 @@ public function getClassAnnotation(string $className, string $annotationClassNam
         }
         $annotations = $this->getClassAnnotations($className, $annotationClassName);
 
-        return $annotations === [] ? null : reset($annotations);
+        return $annotations[0] ?? null;
     }
 
     /**
      * Tells if the specified class implements the given interface
      *
+     * @todo can't this be replaces with is_subclass_of() ?
+     * @param class-string $className
+     * @param class-string $interfaceName
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -476,7 +546,7 @@ public function isClassFinal(string $className): bool
     /**
      * Tells if the specified class is readonly or not
      *
-     * @param string $className Name of the class to analyze
+     * @param class-string $className Name of the class to analyze
      * @return bool true if the class is readonly, otherwise false
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
@@ -492,6 +562,7 @@ public function isClassReadonly(string $className): bool
     /**
      * Tells if the class is unconfigurable or not
      *
+     * @param class-string $className
      * @api
      */
     public function isClassUnconfigurable(string $className): bool
@@ -505,6 +576,7 @@ public function isClassUnconfigurable(string $className): bool
      * Returns all class names of classes containing at least one method annotated
      * with the given annotation class
      *
+     * @return array<int,class-string>
      * @api
      */
     public function getClassesContainingMethodsAnnotatedWith(string $annotationClassName): array
@@ -519,6 +591,7 @@ public function getClassesContainingMethodsAnnotatedWith(string $annotationClass
     /**
      * Returns all names of methods of the given class that are annotated with the given annotation class
      *
+     * @return array<string,string>
      * @api
      */
     public function getMethodsAnnotatedWith(string $className, string $annotationClassName): array
@@ -532,7 +605,7 @@ public function getMethodsAnnotatedWith(string $className, string $annotationCla
     /**
      * Tells if the specified method is final or not
      *
-     * @param string $className
+     * @param class-string $className
      * @param string $methodName
      * @return bool
      * @throws ClassLoadingForReflectionFailedException
@@ -603,6 +676,7 @@ public function isMethodPrivate(string $className, string $methodName): bool
     /**
      * Tells if the specified method is tagged with the given tag
      *
+     * @param class-string $className
      * @throws \ReflectionException
      * @api
      */
@@ -643,9 +717,10 @@ public function isMethodAnnotatedWith(string $className, string $methodName, str
     /**
      * Returns the specified method annotations or an empty array
      *
+     * @template T
      * @param class-string $className
-     * @param class-string|null $annotationClassName
-     * @return array<object>
+     * @param class-string<T>|null $annotationClassName
+     * @return ($annotationClassName is null ? array<object> : array<T>)
      *
      * @throws \ReflectionException
      * @api
@@ -692,6 +767,11 @@ public function getMethodAnnotations(string $className, string $methodName, stri
      * If multiple annotations are set on the target you will
      * get the first instance of them.
      *
+     * @template T of object
+     * @param class-string $className
+     * @param class-string<T> $annotationClassName
+     * @return ?T
+     *
      * @throws \ReflectionException
      */
     public function getMethodAnnotation(string $className, string $methodName, string $annotationClassName): ?object
@@ -740,6 +820,8 @@ public function hasMethod(string $className, string $methodName): bool
      *
      * @throws \ReflectionException
      * @deprecated since 8.4
+     * @param class-string $className
+     * @return array<string,array<int,string>>
      */
     public function getMethodTagsValues(string $className, string $methodName): array
     {
@@ -756,7 +838,18 @@ public function getMethodTagsValues(string $className, string $methodName): arra
      * additional information about the parameter position, type hint etc.
      *
      * @param class-string $className
-     * @return array An array of parameter names and additional information or an empty array of no parameters were found
+     * @return array<string,array{
+     *      position: int,
+     *      optional: bool,
+     *      type: ?string,
+     *      class: ?string,
+     *      array: bool,
+     *      byReference: bool,
+     *      allowsNull: bool,
+     *      defaultValue: mixed,
+     *      scalarDeclaration: bool,
+     *      annotations: array<string,array<int,object>>,
+     * }> An array of parameter names and additional information or an empty array of no parameters were found
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -819,7 +912,7 @@ public function getPropertyNamesByTag(string $className, string $tag): array
      *
      * @param class-string $className
      * @param string $propertyName
-     * @return array
+     * @return array<int|string,array<mixed>>
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -837,7 +930,7 @@ public function getPropertyTagsValues(string $className, string $propertyName):
      * @param class-string $className
      * @param string $propertyName
      * @param string $tag
-     * @return array
+     * @return array<mixed>
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -884,6 +977,7 @@ public function isPropertyPrivate(string $className, string $propertyName): bool
     /**
      * Tells if the specified property is promoted
      *
+     * @param class-string $className
      * @api
      */
     public function isPropertyPromoted(string $className, string $propertyName): bool
@@ -958,10 +1052,11 @@ public function getPropertyNamesByAnnotation(string $className, string $annotati
     /**
      * Returns the specified property annotations or an empty array
      *
+     * @template Annotation of object
      * @param class-string $className
      * @param string $propertyName
-     * @param class-string|null $annotationClassName
-     * @return array<object>
+     * @param class-string<Annotation>|null $annotationClassName
+     * @return ($annotationClassName is null ? array<class-string,array<object>> : array<Annotation>)
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -978,6 +1073,9 @@ public function getPropertyAnnotations(string $className, string $propertyName,
             return $this->classReflectionData[$className][self::DATA_CLASS_PROPERTIES][$propertyName][self::DATA_PROPERTY_ANNOTATIONS];
         }
 
+        /** @phpstan-ignore return.type
+         * (in case of an annotation class name, this is really the annotation instance; The array iss just mixed with arbitrary-string-indexed other objects)
+         */
         return $this->classReflectionData[$className][self::DATA_CLASS_PROPERTIES][$propertyName][self::DATA_PROPERTY_ANNOTATIONS][$annotationClassName] ?? [];
     }
 
@@ -987,10 +1085,11 @@ public function getPropertyAnnotations(string $className, string $propertyName,
      * If multiple annotations are set on the target you will
      * get the first instance of them.
      *
-     * @param string $className
+     * @template Annotation of object
+     * @param class-string $className
      * @param string $propertyName
-     * @param string $annotationClassName
-     * @return object|null
+     * @param class-string<Annotation> $annotationClassName
+     * @return Annotation|null
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -1001,7 +1100,7 @@ public function getPropertyAnnotation(string $className, string $propertyName, s
             $this->initialize();
         }
         $annotations = $this->getPropertyAnnotations($className, $propertyName, $annotationClassName);
-        return $annotations === [] ? null : reset($annotations);
+        return reset($annotations) ?: null;
     }
 
     /**
@@ -1017,8 +1116,8 @@ public function getClassSchema(string|object $classNameOrObject): ?ClassSchema
         }
 
         $className = $classNameOrObject;
-        if (is_object($classNameOrObject)) {
-            $className = TypeHandling::getTypeForValue($classNameOrObject);
+        if (is_object($className)) {
+            $className = TypeHandling::getTypeForValue($className);
         }
         $className = $this->cleanClassName($className);
 
@@ -1034,7 +1133,7 @@ public function getClassSchema(string|object $classNameOrObject): ?ClassSchema
      * Initializes the ReflectionService, cleans the given class name and finally reflects the class if necessary.
      *
      * @param class-string $className
-     * @return string
+     * @return class-string
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -1147,12 +1246,15 @@ protected function reflectClass(string $className): void
         }
 
         if ($class->isAbstract() || $class->isInterface()) {
+            /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
             $this->classReflectionData[$className][self::DATA_CLASS_ABSTRACT] = true;
         }
         if ($class->isFinal()) {
+            /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
             $this->classReflectionData[$className][self::DATA_CLASS_FINAL] = true;
         }
         if ($class->isReadOnly()) {
+            /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
             $this->classReflectionData[$className][self::DATA_CLASS_READONLY] = true;
         }
 
@@ -1167,6 +1269,7 @@ protected function reflectClass(string $className): void
         foreach ($this->annotationReader->getClassAnnotations($class) as $annotation) {
             $annotationClassName = get_class($annotation);
             $this->annotatedClasses[$annotationClassName][$className] = true;
+            /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
             $this->classReflectionData[$className][self::DATA_CLASS_ANNOTATIONS][] = $annotation;
         }
 
@@ -1176,6 +1279,7 @@ protected function reflectClass(string $className): void
                 continue;
             }
             $this->annotatedClasses[$annotationClassName][$className] = true;
+            /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
             $this->classReflectionData[$className][self::DATA_CLASS_ANNOTATIONS][] = $attribute->newInstance();
         }
 
@@ -1194,6 +1298,7 @@ protected function reflectClass(string $className): void
     }
 
     /**
+     * @param class-string $className
      * @return int visibility
      */
     public function reflectClassProperty(string $className, PropertyReflection $property): int
@@ -1203,6 +1308,7 @@ public function reflectClassProperty(string $className, PropertyReflection $prop
         }
 
         $propertyName = $property->getName();
+        /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
         $this->classReflectionData[$className][self::DATA_CLASS_PROPERTIES][$propertyName] = [];
         if ($property->hasType()) {
             $this->classReflectionData[$className][self::DATA_CLASS_PROPERTIES][$propertyName][self::DATA_PROPERTY_TYPE] = trim((string)$property->getType(), '?');
@@ -1242,6 +1348,10 @@ public function reflectClassProperty(string $className, PropertyReflection $prop
         return $visibility;
     }
 
+    /**
+     * @param array<mixed> $tagValues
+     * @return array<mixed>|null
+     */
     protected function reflectPropertyTag(string $className, PropertyReflection $property, string $tagName, array $tagValues): ?array
     {
         if ($this->isTagIgnored($tagName)) {
@@ -1263,20 +1373,25 @@ protected function reflectPropertyTag(string $className, PropertyReflection $pro
     }
 
     /**
+     * @param class-string $className
      * @throws InvalidClassException
      * @throws ClassLoadingForReflectionFailedException
      * @throws \ReflectionException
      */
     protected function addParentClass(string $className, ClassReflection $parentClass): void
     {
+        /** @var class-string $parentClassName */
         $parentClassName = $parentClass->getName();
         if (!$this->isClassReflected($parentClassName)) {
             $this->loadOrReflectClassIfNecessary($parentClassName);
         }
+
+        /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
         $this->classReflectionData[$parentClassName][self::DATA_CLASS_SUBCLASSES][$className] = true;
     }
 
     /**
+     * @param class-string $className
      * @throws ClassLoadingForReflectionFailedException
      * @throws InvalidClassException
      * @throws \ReflectionException
@@ -1292,6 +1407,7 @@ protected function addImplementedInterface(string $className, ClassReflection $i
             $this->loadOrReflectClassIfNecessary($interfaceName);
         }
 
+        /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
         $this->classReflectionData[$interfaceName][self::DATA_INTERFACE_IMPLEMENTATIONS][$className] = true;
     }
 
@@ -1304,11 +1420,14 @@ protected function reflectClassMethod(string $className, MethodReflection $metho
     {
         $methodName = $method->getName();
         if ($method->isFinal()) {
+            /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
             $this->classReflectionData[$className][self::DATA_CLASS_METHODS][$methodName][self::DATA_METHOD_FINAL] = true;
         }
         if ($method->isStatic()) {
+            /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
             $this->classReflectionData[$className][self::DATA_CLASS_METHODS][$methodName][self::DATA_METHOD_STATIC] = true;
         }
+        /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
         $this->classReflectionData[$className][self::DATA_CLASS_METHODS][$methodName][self::DATA_METHOD_VISIBILITY] = $this->extractVisibility($method);
 
         foreach ($this->getMethodAnnotations($className, $methodName) as $methodAnnotation) {
@@ -1340,6 +1459,7 @@ protected function reflectClassMethod(string $className, MethodReflection $metho
                 }
             }
         }
+        /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
         $this->classReflectionData[$className][self::DATA_CLASS_METHODS][$methodName][self::DATA_METHOD_DECLARED_RETURN_TYPE] = $returnType;
 
         foreach ($method->getParameters() as $parameter) {
@@ -1364,6 +1484,7 @@ protected function reflectClassMethodParameter(string $className, MethodReflecti
         $methodName = $method->getName();
         $paramAnnotations = $method->isTaggedWith('param') ? $method->getTagValues('param') : [];
 
+        /** @phpstan-ignore offsetAccess.nonOffsetAccessible (is not false, todo simplify structure to always be an array) */
         $this->classReflectionData[$className][self::DATA_CLASS_METHODS][$methodName][self::DATA_METHOD_PARAMETERS][$parameter->getName()] = $this->convertParameterReflectionToArray($parameter, $method);
         if (!isset($this->settings['logIncorrectDocCommentHints']) || $this->settings['logIncorrectDocCommentHints'] !== true) {
             return;
@@ -1381,7 +1502,7 @@ protected function reflectClassMethodParameter(string $className, MethodReflecti
         }
 
         if (
-            isset($this->classReflectionData[$className][self::DATA_CLASS_METHODS][$methodName][self::DATA_METHOD_PARAMETERS][$parameter->getName()][self::DATA_PARAMETER_TYPE]) &&
+            isset($this->classReflectionData[$className][self::DATA_CLASS_METHODS][$methodName][self::DATA_METHOD_PARAMETERS][$parameter->getName()][self::DATA_PARAMETER_TYPE]) && class_exists($parameterAnnotation[0]) &&
             $this->classReflectionData[$className][self::DATA_CLASS_METHODS][$methodName][self::DATA_METHOD_PARAMETERS][$parameter->getName()][self::DATA_PARAMETER_TYPE] !== $this->cleanClassName($parameterAnnotation[0])
         ) {
             $this->log('  Wrong type in @param for "' . $method->getName() . '::' . $parameter->getName() . '": "' . $parameterAnnotation[0] . '"', LogLevel::DEBUG);
@@ -1447,6 +1568,7 @@ protected function expandType(ClassReflection $class, string $type): string
     /**
      * Finds all parent classes of the given class
      *
+     * @param array<int,ClassReflection> $parentClasses
      * @return array<ClassReflection>
      */
     protected function getParentClasses(ClassReflection $class, array $parentClasses = []): array
@@ -1514,7 +1636,11 @@ protected function buildClassSchema(string $className): ClassSchema
         }
 
         $possibleRepositoryClassName = str_replace('\\Model\\', '\\Repository\\', $className) . 'Repository';
-        if ($this->isClassReflected($possibleRepositoryClassName) === true) {
+        if (
+            class_exists($possibleRepositoryClassName)
+            && is_subclass_of($possibleRepositoryClassName, RepositoryInterface::class)
+            && $this->isClassReflected($possibleRepositoryClassName) === true
+        ) {
             $classSchema->setRepositoryClassName($possibleRepositoryClassName);
         }
 
@@ -1540,7 +1666,6 @@ protected function addPropertiesToClassSchema(ClassSchema $classSchema): void
         $className = $classSchema->getClassName();
         $skipArtificialIdentity = false;
 
-        /* @var $valueObjectAnnotation Flow\ValueObject */
         $valueObjectAnnotation = $this->getClassAnnotation($className, Flow\ValueObject::class);
         if ($valueObjectAnnotation !== null && $valueObjectAnnotation->embedded === true) {
             $skipArtificialIdentity = true;
@@ -1594,6 +1719,9 @@ protected function evaluateClassPropertyAnnotationsForSchema(ClassSchema $classS
         }
 
         $declaredType = strtok(trim(current($varTagValues), " \n\t"), " \n\t");
+        if ($declaredType === false) {
+            throw new \Exception('Invalid type for ' . $className . '::$' . $propertyName, 1744046737);
+        }
 
         if ($this->isPropertyAnnotatedWith($className, $propertyName, ORM\Id::class)) {
             $skipArtificialIdentity = true;
@@ -1644,7 +1772,7 @@ protected function completeRepositoryAssignments(): void
         }
 
         foreach ($this->classSchemata as $classSchema) {
-            if ($classSchema instanceof ClassSchema && class_exists($classSchema->getClassName()) && $classSchema->isAggregateRoot()) {
+            if (class_exists($classSchema->getClassName()) && $classSchema->isAggregateRoot()) {
                 $this->makeChildClassesAggregateRoot($classSchema);
             }
         }
@@ -1684,7 +1812,7 @@ protected function makeChildClassesAggregateRoot(ClassSchema $classSchema): void
     protected function ensureAggregateRootInheritanceChainConsistency(): void
     {
         foreach ($this->classSchemata as $className => $classSchema) {
-            if (!class_exists($className) || ($classSchema instanceof ClassSchema && $classSchema->isAggregateRoot() === false)) {
+            if (!class_exists($className) || ($classSchema->isAggregateRoot() === false)) {
                 continue;
             }
 
@@ -1726,8 +1854,30 @@ protected function checkValueObjectRequirements(string $className): void
      * Converts the internal, optimized data structure of parameter information into
      * a human-friendly array with speaking indexes.
      *
-     * @param array $parametersInformation Raw, internal parameter information
-     * @return array Developer friendly version
+     * @param array<string,array{
+     *     16: int,
+     *     17?: true,
+     *     18?: string,
+     *     19?: true,
+     *     20?: string,
+     *     21?: true,
+     *     22?: mixed,
+     *     23?: true,
+     *     24?: true,
+     *     25?: array<string,array<int,object>>,
+     * }> $parametersInformation Raw, internal parameter information
+     * @return array<string,array{
+     *     position: int,
+     *     optional: bool,
+     *     type: ?string,
+     *     class: ?string,
+     *     array: bool,
+     *     byReference: bool,
+     *     allowsNull: bool,
+     *     defaultValue: mixed,
+     *     scalarDeclaration: bool,
+     *     annotations: array<string,array<int,object>>,
+     * }> Developer friendly version
      */
     protected function convertParameterDataToArray(array $parametersInformation): array
     {
@@ -1736,7 +1886,7 @@ protected function convertParameterDataToArray(array $parametersInformation): ar
             $parameters[$parameterName] = [
                 'position' => $parameterData[self::DATA_PARAMETER_POSITION],
                 'optional' => isset($parameterData[self::DATA_PARAMETER_OPTIONAL]),
-                'type' => $parameterData[self::DATA_PARAMETER_TYPE],
+                'type' => $parameterData[self::DATA_PARAMETER_TYPE] ?? null,
                 'class' => $parameterData[self::DATA_PARAMETER_CLASS] ?? null,
                 'array' => isset($parameterData[self::DATA_PARAMETER_ARRAY]),
                 'byReference' => isset($parameterData[self::DATA_PARAMETER_BY_REFERENCE]),
@@ -1753,7 +1903,18 @@ protected function convertParameterDataToArray(array $parametersInformation): ar
     /**
      * Converts the given parameter reflection into an information array
      *
-     * @return array Parameter information array
+     * @return array{
+     *     16: int,
+     *     17?: true,
+     *     18?: string,
+     *     19?: true,
+     *     20?: string,
+     *     21?: true,
+     *     22?: mixed,
+     *     23?: true,
+     *     24?: true,
+     *     25?: array<string,array<int,object>>
+     * } Parameter information array
      */
     protected function convertParameterReflectionToArray(ParameterReflection $parameter, MethodReflection $method): array
     {
@@ -1794,7 +1955,7 @@ protected function convertParameterReflectionToArray(ParameterReflection $parame
                 break;
             }
         }
-        if (!isset($parameterInformation[self::DATA_PARAMETER_TYPE]) && $parameterType !== null) {
+        if (!isset($parameterInformation[self::DATA_PARAMETER_TYPE]) && $parameterType !== null && class_exists($parameterType)) {
             $parameterInformation[self::DATA_PARAMETER_TYPE] = $this->cleanClassName($parameterType);
         } elseif (!isset($parameterInformation[self::DATA_PARAMETER_TYPE])) {
             $parameterInformation[self::DATA_PARAMETER_TYPE] = 'mixed';
@@ -1820,7 +1981,7 @@ protected function convertParameterReflectionToArray(ParameterReflection $parame
     protected function forgetChangedClasses(): void
     {
         foreach ($this->classReflectionData as $className => $_) {
-            if (is_string($className) && !$this->reflectionDataRuntimeCache->has($this->produceCacheIdentifierFromClassName($className))) {
+            if (!$this->reflectionDataRuntimeCache->has($this->produceCacheIdentifierFromClassName($className))) {
                 $this->forgetClass($className);
             }
         }
@@ -1953,6 +2114,8 @@ public function saveToCache(): void
 
     /**
      * Clean a given class name from possibly prefixed backslash
+     * @param class-string $className
+     * @return class-string
      */
     protected function cleanClassName(string $className): string
     {
@@ -1969,6 +2132,7 @@ protected function produceCacheIdentifierFromClassName(string $className): strin
 
     /**
      * Writes the given message along with the additional information into the log.
+     * @param array<string,mixed> $additionalData
      */
     protected function log(string $message, string $severity = LogLevel::INFO, array $additionalData = []): void
     {
@@ -1992,7 +2156,7 @@ function (\ReflectionNamedType|\ReflectionIntersectionType $type) {
                 $parameterType->getTypes()
             )),
             $parameterType instanceof \ReflectionIntersectionType => implode('&', array_map(
-                function (\ReflectionNamedType $type) {
+                function (\ReflectionType $type) {
                     return $this->renderParameterType($type);
                 },
                 $parameterType->getTypes()
diff --git a/Neos.Flow/Classes/Reflection/ReflectionServiceFactory.php b/Neos.Flow/Classes/Reflection/ReflectionServiceFactory.php
index e3e5ed1429..61ef500d0f 100644
--- a/Neos.Flow/Classes/Reflection/ReflectionServiceFactory.php
+++ b/Neos.Flow/Classes/Reflection/ReflectionServiceFactory.php
@@ -11,6 +11,7 @@
  * source code.
  */
 
+use Neos\Cache\Frontend\VariableFrontend;
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\Cache\CacheManager;
 use Neos\Flow\Configuration\ConfigurationManager;
@@ -62,8 +63,16 @@ public function create(): ReflectionService
         $reflectionService = new ReflectionService();
         $reflectionService->injectLogger($this->bootstrap->getEarlyInstance(PsrLoggerFactoryInterface::class)->get('systemLogger'));
         $reflectionService->injectSettings($settings);
-        $reflectionService->setReflectionDataRuntimeCache($cacheManager->getCache('Flow_Reflection_RuntimeData'));
-        $reflectionService->setClassSchemataRuntimeCache($cacheManager->getCache('Flow_Reflection_RuntimeClassSchemata'));
+        $runtimeDataCache = $cacheManager->getCache('Flow_Reflection_RuntimeData');
+        if (!$runtimeDataCache instanceof VariableFrontend) {
+            throw new \Exception('Cache Flow_Reflection_RuntimeData must have a VariableFrontend', 1743972055);
+        }
+        $reflectionService->setReflectionDataRuntimeCache($runtimeDataCache);
+        $runtimeClassSchemataCache = $cacheManager->getCache('Flow_Reflection_RuntimeClassSchemata');
+        if (!$runtimeClassSchemataCache instanceof VariableFrontend) {
+            throw new \Exception('Cache Flow_Reflection_RuntimeClassSchemata must have a VariableFrontend', 1743972058);
+        }
+        $reflectionService->setClassSchemataRuntimeCache($runtimeClassSchemataCache);
 
         $this->reflectionService = $reflectionService;
         return $reflectionService;
diff --git a/Neos.Flow/Classes/ResourceManagement/Collection.php b/Neos.Flow/Classes/ResourceManagement/Collection.php
index 6b07307bb0..275e85cf4c 100644
--- a/Neos.Flow/Classes/ResourceManagement/Collection.php
+++ b/Neos.Flow/Classes/ResourceManagement/Collection.php
@@ -40,7 +40,7 @@ class Collection implements CollectionInterface
     protected $target;
 
     /**
-     * @var array
+     * @var array<string>
      */
     protected $pathPatterns;
 
@@ -56,7 +56,7 @@ class Collection implements CollectionInterface
      * @param string $name User-space name of this collection, as specified in the settings
      * @param StorageInterface $storage The storage for data used in this collection
      * @param TargetInterface $target The publication target for this collection
-     * @param array $pathPatterns Glob patterns for paths to consider – only supported by specific storages
+     * @param array<string> $pathPatterns Glob patterns for paths to consider – only supported by specific storages
      */
     public function __construct($name, StorageInterface $storage, TargetInterface $target, array $pathPatterns)
     {
diff --git a/Neos.Flow/Classes/ResourceManagement/EelHelper/StaticResourceHelper.php b/Neos.Flow/Classes/ResourceManagement/EelHelper/StaticResourceHelper.php
index a4f61a2a13..fbaf18510e 100644
--- a/Neos.Flow/Classes/ResourceManagement/EelHelper/StaticResourceHelper.php
+++ b/Neos.Flow/Classes/ResourceManagement/EelHelper/StaticResourceHelper.php
@@ -73,7 +73,7 @@ protected function getLocalizedResourcePath(string $packageKey, string $pathAndF
         $resourcePath = sprintf('resource://%s/%s', $packageKey, $pathAndFilename);
         if ($localize === true) {
             $localizedResourcePathData = $this->i18nService->getLocalizedFilename($resourcePath);
-            $resourcePath = $localizedResourcePathData[0] ?? $resourcePath;
+            $resourcePath = $localizedResourcePathData[0];
         }
         return $resourcePath;
     }
diff --git a/Neos.Flow/Classes/ResourceManagement/PersistentResource.php b/Neos.Flow/Classes/ResourceManagement/PersistentResource.php
index f431792dde..4e47d9f839 100644
--- a/Neos.Flow/Classes/ResourceManagement/PersistentResource.php
+++ b/Neos.Flow/Classes/ResourceManagement/PersistentResource.php
@@ -179,7 +179,7 @@ public function setFilename($filename)
         $this->throwExceptionIfProtected();
 
         $pathInfo = UnicodeFunctions::pathinfo($filename);
-        $extension = (isset($pathInfo['extension']) ? '.' . strtolower($pathInfo['extension']) : '');
+        $extension = '.' . strtolower($pathInfo['extension']);
         $this->filename = $pathInfo['filename'] . $extension;
         $this->mediaType = Utility\MediaTypes::getMediaTypeFromFilename($this->filename);
     }
@@ -298,10 +298,10 @@ public function getSha1()
      * @return void
      * @api
      */
-    public function setSha1($sha1)
+    public function setSha1(string $sha1)
     {
         $this->throwExceptionIfProtected();
-        if (!is_string($sha1) || preg_match('/[A-Fa-f0-9]{40}/', $sha1) !== 1) {
+        if (preg_match('/[A-Fa-f0-9]{40}/', $sha1) !== 1) {
             throw new \InvalidArgumentException('Specified invalid hash to setSha1()', 1362564220);
         }
         $this->sha1 = strtolower($sha1);
@@ -330,9 +330,9 @@ public function createTemporaryLocalCopy()
             $temporaryPathAndFilename .= '-' . microtime(true);
 
             if (function_exists('posix_getpid')) {
-                $temporaryPathAndFilename .= '-' . str_pad(posix_getpid(), 10);
+                $temporaryPathAndFilename .= '-' . str_pad((string)posix_getpid(), 10);
             } else {
-                $temporaryPathAndFilename .= '-' . (string) getmypid();
+                $temporaryPathAndFilename .= '-' . getmypid();
             }
 
             $temporaryPathAndFilename = trim($temporaryPathAndFilename);
@@ -364,7 +364,9 @@ public function postPersist()
     {
         if ($this->lifecycleEventsActive) {
             $collection = $this->resourceManager->getCollection($this->collectionName);
-            $collection->getTarget()->publishResource($this, $collection);
+            if ($collection) {
+                $collection->getTarget()->publishResource($this, $collection);
+            }
         }
     }
 
diff --git a/Neos.Flow/Classes/ResourceManagement/Publishing/MessageCollector.php b/Neos.Flow/Classes/ResourceManagement/Publishing/MessageCollector.php
index ffba74d24a..b5b6ecefc0 100644
--- a/Neos.Flow/Classes/ResourceManagement/Publishing/MessageCollector.php
+++ b/Neos.Flow/Classes/ResourceManagement/Publishing/MessageCollector.php
@@ -35,7 +35,7 @@ class MessageCollector
     ];
 
     /**
-     * @var \SplObjectStorage
+     * @var \SplObjectStorage<Message,mixed>
      */
     protected $messages;
 
diff --git a/Neos.Flow/Classes/ResourceManagement/ResourceManager.php b/Neos.Flow/Classes/ResourceManagement/ResourceManager.php
index 8956aa1770..c513b5bb7a 100644
--- a/Neos.Flow/Classes/ResourceManagement/ResourceManager.php
+++ b/Neos.Flow/Classes/ResourceManagement/ResourceManager.php
@@ -65,7 +65,7 @@ class ResourceManager
     protected $persistenceManager;
 
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $settings;
 
@@ -98,7 +98,7 @@ class ResourceManager
     /**
      * Injects the settings of this package
      *
-     * @param array $settings
+     * @param array<string,mixed> $settings
      * @return void
      */
     public function injectSettings(array $settings)
@@ -156,7 +156,6 @@ public function importResource($source, $collectionName = ResourceManager::DEFAU
             throw new Exception(sprintf('Tried to import a file into the resource collection "%s" but no such collection exists. Please check your settings and the code which triggered the import.', $collectionName), 1375196643);
         }
 
-        /* @var CollectionInterface $collection */
         $collection = $this->collections[$collectionName];
 
         try {
@@ -165,15 +164,17 @@ public function importResource($source, $collectionName = ResourceManager::DEFAU
                 ObjectAccess::setProperty($resource, 'Persistence_Object_Identifier', $forcedPersistenceObjectIdentifier, true);
             }
             if (!is_resource($source)) {
+                /** @var string $source */
                 $pathInfo = UnicodeFunctions::pathinfo($source);
+                /** @var PersistentResource $resource */
                 $resource->setFilename($pathInfo['basename']);
             }
         } catch (Exception $exception) {
             throw new Exception(sprintf('Importing a file into the resource collection "%s" failed: %s', $collectionName, $exception->getMessage()), 1375197120, $exception);
         }
-
+        /** @var PersistentResource $resource */
         $this->resourceRepository->add($resource);
-        $this->logger->debug(sprintf('Successfully imported file "%s" into the resource collection "%s" (storage: %s, a %s. SHA1: %s)', $source, $collectionName, $collection->getStorage()->getName(), get_class($collection), $resource->getSha1()));
+        $this->logger->debug(sprintf('Successfully imported file into the resource collection "%s" (storage: %s, a %s. SHA1: %s)', $collectionName, $collection->getStorage()->getName(), get_class($collection), $resource->getSha1()));
         return $resource;
     }
 
@@ -195,18 +196,14 @@ public function importResource($source, $collectionName = ResourceManager::DEFAU
      * @throws Exception
      * @api
      */
-    public function importResourceFromContent($content, $filename, $collectionName = ResourceManager::DEFAULT_PERSISTENT_COLLECTION_NAME, $forcedPersistenceObjectIdentifier = null)
+    public function importResourceFromContent(string $content, $filename, $collectionName = ResourceManager::DEFAULT_PERSISTENT_COLLECTION_NAME, $forcedPersistenceObjectIdentifier = null)
     {
-        if (!is_string($content)) {
-            throw new Exception(sprintf('Tried to import content into the resource collection "%s" but the given content was a %s instead of a string.', $collectionName, gettype($content)), 1380878115);
-        }
         $this->initialize();
 
         if (!isset($this->collections[$collectionName])) {
             throw new Exception(sprintf('Tried to import a file into the resource collection "%s" but no such collection exists. Please check your settings and the code which triggered the import.', $collectionName), 1380878131);
         }
 
-        /* @var CollectionInterface $collection */
         $collection = $this->collections[$collectionName];
 
         try {
@@ -219,6 +216,7 @@ public function importResourceFromContent($content, $filename, $collectionName =
             throw new Exception(sprintf('Importing content into the resource collection "%s" failed: %s', $collectionName, $exception->getMessage()), 1381156155, $exception);
         }
 
+        /** @var PersistentResource $resource */
         $this->resourceRepository->add($resource);
         $this->logger->debug(sprintf('Successfully imported content into the resource collection "%s" (storage: %s, a %s. SHA1: %s)', $collectionName, $collection->getStorage()->getName(), get_class($collection->getStorage()), $resource->getSha1()));
 
@@ -232,7 +230,7 @@ public function importResourceFromContent($content, $filename, $collectionName =
      * On a successful import this method returns a PersistentResource object representing
      * the newly imported persistent resource.
      *
-     * @param array $uploadInfo An array detailing the resource to import (expected keys: name, tmp_name)
+     * @param array<string,mixed> $uploadInfo An array detailing the resource to import (expected keys: name, tmp_name)
      * @param string $collectionName Name of the collection this uploaded resource should be added to
      * @return PersistentResource A resource object representing the imported resource
      * @throws Exception
@@ -303,7 +301,7 @@ public function getStreamByResource(PersistentResource $resource)
      * $resource2 => array('originalFilename' => 'Bar.txt'),
      * ...
      *
-     * @return \SplObjectStorage
+     * @return \SplObjectStorage<PersistentResource,mixed>
      * @api
      */
     public function getImportedResources()
@@ -449,7 +447,7 @@ public function getPublicPackageResourceUriByPath($path)
      * Return the package key and the relative path and filename from the given resource path
      *
      * @param string $path The ressource path, like resource://Your.Package/Public/Image/Dummy.png
-     * @return array The array contains two value, first the packageKey followed by the relativePathAndFilename
+     * @return array{0: string, 1: string} The array contains two value, first the packageKey followed by the relativePathAndFilename
      * @throws Exception
      * @api
      */
@@ -554,7 +552,10 @@ protected function initializeStorages()
             if (!class_exists($storageDefinition['storage'])) {
                 throw new Exception(sprintf('The configuration for the resource storage "%s" defined in your settings has not defined a valid "storage" option. Please check the configuration syntax and make sure that the specified class "%s" really exists.', $storageName, $storageDefinition['storage']), 1361467212);
             }
-            $options = (isset($storageDefinition['storageOptions']) ? $storageDefinition['storageOptions'] : []);
+            if (!is_subclass_of($storageDefinition['storage'], StorageInterface::class)) {
+                throw new Exception('Configured storage ' . $storageDefinition['storage'] . ' does not implement the required ' . StorageInterface::class, 1743970047);
+            }
+            $options = ($storageDefinition['storageOptions'] ?? []);
             $this->storages[$storageName] = new $storageDefinition['storage']($storageName, $options);
         }
     }
@@ -574,7 +575,10 @@ protected function initializeTargets()
             if (!class_exists($targetDefinition['target'])) {
                 throw new Exception(sprintf('The configuration for the resource target "%s" defined in your settings has not defined a valid "target" option. Please check the configuration syntax and make sure that the specified class "%s" really exists.', $targetName, $targetDefinition['target']), 1361467839);
             }
-            $options = (isset($targetDefinition['targetOptions']) ? $targetDefinition['targetOptions'] : []);
+            if (!is_subclass_of($targetDefinition['target'], TargetInterface::class)) {
+                throw new Exception('Configured resource target ' . $targetDefinition['target'] . ' does not implement the required ' . TargetInterface::class, 1743969958);
+            }
+            $options = $targetDefinition['targetOptions'] ?? [];
             $this->targets[$targetName] = new $targetDefinition['target']($targetName, $options);
         }
     }
@@ -612,21 +616,24 @@ protected function initializeCollections()
      * Prepare an uploaded file to be imported as resource object. Will check the validity of the file,
      * move it outside of upload folder if open_basedir is enabled and check the filename.
      *
-     * @param array $uploadInfo
-     * @return array Array of string with the two keys "filepath" (the path to get the filecontent from) and "filename" the filename of the originally uploaded file.
+     * @param array<string,mixed> $uploadInfo
+     * @return array{filepath: string, filename: string} Array of string with the two keys "filepath" (the path to get the filecontent from) and "filename" the filename of the originally uploaded file.
      * @throws Exception
      */
     protected function prepareUploadedFileForImport(array $uploadInfo)
     {
         $openBasedirEnabled = (boolean)ini_get('open_basedir');
-        $temporaryTargetPathAndFilename = $uploadInfo['tmp_name'];
+        $temporaryTargetPathAndFilename = $uploadInfo['tmp_name'] ?? null;
+        if (!is_string($temporaryTargetPathAndFilename)) {
+            throw new \Exception('String tmp_name required', 1743969722);
+        }
         $pathInfo = UnicodeFunctions::pathinfo($uploadInfo['name']);
 
         if (!is_uploaded_file($temporaryTargetPathAndFilename)) {
             throw new Exception('The given upload file "' . strip_tags($pathInfo['basename']) . '" was not uploaded through PHP. As it could pose a security risk it cannot be imported.', 1422461503);
         }
 
-        if (isset($pathInfo['extension']) && array_key_exists(strtolower($pathInfo['extension']), $this->settings['extensionsBlockedFromUpload']) && $this->settings['extensionsBlockedFromUpload'][strtolower($pathInfo['extension'])] === true) {
+        if (array_key_exists(strtolower($pathInfo['extension']), $this->settings['extensionsBlockedFromUpload']) && $this->settings['extensionsBlockedFromUpload'][strtolower($pathInfo['extension'])] === true) {
             throw new Exception('The extension of the given upload file "' . strip_tags($pathInfo['basename']) . '" is excluded. As it could pose a security risk it cannot be imported.', 1447148472);
         }
 
@@ -645,7 +652,7 @@ protected function prepareUploadedFileForImport(array $uploadInfo)
 
         return [
             'filepath' => $temporaryTargetPathAndFilename,
-            'filename' => $pathInfo['basename']
+            'filename' => $pathInfo['basename'],
         ];
     }
 }
diff --git a/Neos.Flow/Classes/ResourceManagement/ResourceMetaDataInterface.php b/Neos.Flow/Classes/ResourceManagement/ResourceMetaDataInterface.php
index 8cd9b10a9d..89556eac2e 100644
--- a/Neos.Flow/Classes/ResourceManagement/ResourceMetaDataInterface.php
+++ b/Neos.Flow/Classes/ResourceManagement/ResourceMetaDataInterface.php
@@ -80,5 +80,5 @@ public function getSha1();
      * @param string $sha1 The sha1 hash
      * @return void
      */
-    public function setSha1($sha1);
+    public function setSha1(string $sha1);
 }
diff --git a/Neos.Flow/Classes/ResourceManagement/ResourceRepository.php b/Neos.Flow/Classes/ResourceManagement/ResourceRepository.php
index 82bb9dcf7a..605ba63894 100644
--- a/Neos.Flow/Classes/ResourceManagement/ResourceRepository.php
+++ b/Neos.Flow/Classes/ResourceManagement/ResourceRepository.php
@@ -48,12 +48,12 @@ class ResourceRepository extends Repository
     protected $persistenceManager;
 
     /**
-     * @var \SplObjectStorage|PersistentResource[]
+     * @var \SplObjectStorage<PersistentResource,mixed>
      */
     protected $removedResources;
 
     /**
-     * @var \SplObjectStorage|PersistentResource[]
+     * @var \SplObjectStorage<PersistentResource,mixed>
      */
     protected $addedResources;
 
@@ -73,6 +73,9 @@ public function __construct()
      */
     public function add($object): void
     {
+        if (!($object instanceof PersistentResource)) {
+            throw new \Exception('Can only add objects of type PersistentResource', 1743969457);
+        }
         $this->persistenceManager->allowObject($object);
         if ($this->removedResources->contains($object)) {
             $this->removedResources->detach($object);
@@ -91,6 +94,9 @@ public function add($object): void
      */
     public function remove($object): void
     {
+        if (!($object instanceof PersistentResource)) {
+            throw new \Exception('Can only remove objects of type PersistentResource', 1743969438);
+        }
         // Intercept a second call for the same PersistentResource object because it might cause an endless loop caused by
         // the ResourceManager's deleteResource() method which also calls this remove() function:
         if (!$this->removedResources->contains($object)) {
@@ -188,7 +194,7 @@ public function findSimilarResources(PersistentResource $resource)
      * Find all resources with the same SHA1 hash
      *
      * @param string $sha1Hash
-     * @return array
+     * @return array<PersistentResource>
      */
     public function findBySha1($sha1Hash)
     {
@@ -209,7 +215,7 @@ public function findBySha1($sha1Hash)
      *
      * @param string $sha1Hash
      * @param string $collectionName
-     * @return array
+     * @return array<PersistentResource>
      */
     public function findBySha1AndCollectionName($sha1Hash, $collectionName)
     {
@@ -261,16 +267,15 @@ public function countBySha1AndCollectionName(string $sha1Hash, string $collectio
      * Find one resource by SHA1
      *
      * @param string $sha1Hash
-     * @return PersistentResource
+     * @return ?PersistentResource
      */
     public function findOneBySha1($sha1Hash)
     {
         $query = $this->createQuery();
         $query->matching($query->equals('sha1', $sha1Hash))->setLimit(1);
-        /** @var PersistentResource $resource */
+        /** @var ?PersistentResource $resource */
         $resource = $query->execute()->getFirst();
         if ($resource === null) {
-            /** @var PersistentResource $importedResource */
             foreach ($this->addedResources as $importedResource) {
                 if ($importedResource->getSha1() === $sha1Hash) {
                     return $importedResource;
@@ -282,7 +287,7 @@ public function findOneBySha1($sha1Hash)
     }
 
     /**
-     * @return \SplObjectStorage
+     * @return \SplObjectStorage<PersistentResource,mixed>
      */
     public function getAddedResources()
     {
diff --git a/Neos.Flow/Classes/ResourceManagement/ResourceTypeConverter.php b/Neos.Flow/Classes/ResourceManagement/ResourceTypeConverter.php
index fc81836e5b..cb806ee1d2 100644
--- a/Neos.Flow/Classes/ResourceManagement/ResourceTypeConverter.php
+++ b/Neos.Flow/Classes/ResourceManagement/ResourceTypeConverter.php
@@ -119,7 +119,7 @@ class ResourceTypeConverter extends AbstractTypeConverter
     protected $logger;
 
     /**
-     * @var array
+     * @var array<string,PersistentResource>
      */
     protected $convertedResources = [];
 
@@ -144,9 +144,9 @@ public function injectLogger(LoggerInterface $logger)
      * Note that $source['error'] will also be present if a file was successfully
      * uploaded. In that case its value will be \UPLOAD_ERR_OK.
      *
-     * @param array|string|UploadedFileInterface $source The upload info (expected keys: error, name, tmp_name), the hash or an UploadedFile
+     * @param array<string,mixed>|string|UploadedFileInterface $source The upload info (expected keys: error, name, tmp_name), the hash or an UploadedFile
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return PersistentResource|null|FlowError if the input format is not supported or could not be converted for other reasons
      * @throws Exception
@@ -177,7 +177,7 @@ public function convertFrom($source, $targetType, array $convertedChildPropertie
     }
 
     /**
-     * @param array $source
+     * @param array<string,mixed> $source
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return PersistentResource|null|FlowError
      */
@@ -219,7 +219,7 @@ protected function handleFileUploads(array $source, ?PropertyMappingConfiguratio
     }
 
     /**
-     * @param array $source
+     * @param array<string,mixed> $source
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return PersistentResource|FlowError
      * @throws Exception
@@ -256,12 +256,13 @@ protected function handleHashAndData(array $source, ?PropertyMappingConfiguratio
             if (isset($source['data']) && isset($source['filename'])) {
                 $resource = $this->resourceManager->importResourceFromContent(base64_decode($source['data']), $source['filename'], $collectionName, $givenResourceIdentity);
             } elseif ($hash !== null) {
-                $resource = $this->resourceManager->importResource($configuration->getConfigurationValue(ResourceTypeConverter::class, self::CONFIGURATION_RESOURCE_LOAD_PATH) . '/' . $hash, $collectionName, $givenResourceIdentity);
-                if (is_array($source) && isset($source['filename'])) {
-                    $resource->setFilename($source['filename']);
+                $resource = $this->resourceManager->importResource($configuration?->getConfigurationValue(ResourceTypeConverter::class, self::CONFIGURATION_RESOURCE_LOAD_PATH) . '/' . $hash, $collectionName, $givenResourceIdentity);
+                $filename = $source['filename'] ?? null;
+                if (is_string($filename)) {
+                    $resource->setFilename($filename);
                 }
             }
-            if ($hash !== null && $resource->getSha1() !== $hash) {
+            if ($hash !== null && $resource?->getSha1() !== $hash) {
                 throw new Exception\InvalidResourceDataException('The source SHA1 did not match the SHA1 of the imported resource.', 1482248149);
             }
         }
@@ -297,7 +298,7 @@ protected function handleUploadedFile(UploadedFileInterface $source, ?PropertyMa
             case \UPLOAD_ERR_PARTIAL:
                 return new FlowError(Files::getUploadErrorMessage($source->getError()), 1264440823);
             default:
-                $this->logger->error(sprintf('A server error occurred while converting an uploaded resource: "%s"', Files::getUploadErrorMessage($source['error'])), LogEnvironment::fromMethodName(__METHOD__));
+                $this->logger->error(sprintf('A server error occurred while converting an uploaded resource: "%s"', Files::getUploadErrorMessage($source->getError())), LogEnvironment::fromMethodName(__METHOD__));
 
                 return new FlowError('An error occurred while uploading. Please try again or contact the administrator if the problem remains', 1340193849);
         }
@@ -307,8 +308,15 @@ protected function handleUploadedFile(UploadedFileInterface $source, ?PropertyMa
         }
 
         try {
-            $resource = $this->resourceManager->importResource($source->getStream()->detach(), $this->getCollectionName($source, $configuration));
-            $resource->setFilename($source->getClientFilename());
+            $sourceForImport = $source->getStream()->detach();
+            if ($sourceForImport === null) {
+                throw new \Exception('Failed to detach resource from stream', 1743967911);
+            }
+            $resource = $this->resourceManager->importResource($sourceForImport, $this->getCollectionName($source, $configuration));
+            $filename = $source->getClientFilename();
+            if ($filename !== null) {
+                $resource->setFilename($filename);
+            }
             $this->convertedResources[spl_object_hash($source)] = $resource;
             return $resource;
         } catch (\Exception $exception) {
@@ -324,7 +332,7 @@ protected function handleUploadedFile(UploadedFileInterface $source, ?PropertyMa
      * The propertyMappingConfiguration CONFIGURATION_COLLECTION_NAME will directly override the default. Then if CONFIGURATION_ALLOW_COLLECTION_OVERRIDE is true
      * and __collectionName is in the $source this will finally be the value.
      *
-     * @param array|UploadedFileInterface $source
+     * @param array<string,mixed>|UploadedFileInterface $source
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return string
      * @throws InvalidPropertyMappingConfigurationException
diff --git a/Neos.Flow/Classes/ResourceManagement/Storage/FileSystemStorage.php b/Neos.Flow/Classes/ResourceManagement/Storage/FileSystemStorage.php
index 6e4f0536cf..ad0ee6580c 100644
--- a/Neos.Flow/Classes/ResourceManagement/Storage/FileSystemStorage.php
+++ b/Neos.Flow/Classes/ResourceManagement/Storage/FileSystemStorage.php
@@ -59,7 +59,7 @@ class FileSystemStorage implements StorageInterface
      * Constructor
      *
      * @param string $name Name of this storage instance, according to the resource settings
-     * @param array $options Options for this storage
+     * @param array<string,mixed> $options Options for this storage
      * @throws Exception
      */
     public function __construct($name, array $options = [])
diff --git a/Neos.Flow/Classes/ResourceManagement/Storage/PackageStorage.php b/Neos.Flow/Classes/ResourceManagement/Storage/PackageStorage.php
index d0ff7285aa..23ead9adba 100644
--- a/Neos.Flow/Classes/ResourceManagement/Storage/PackageStorage.php
+++ b/Neos.Flow/Classes/ResourceManagement/Storage/PackageStorage.php
@@ -71,7 +71,10 @@ public function getObjectsByPathPattern($pattern)
             if ($directoryPattern === '*') {
                 $directories[$packageKey][] = $package->getPackagePath();
             } else {
-                $directories[$packageKey] = glob($package->getPackagePath() . $directoryPattern, GLOB_ONLYDIR);
+                $packageDirectories = glob($package->getPackagePath() . $directoryPattern, GLOB_ONLYDIR);
+                if ($packageDirectories !== false) {
+                    $directories[$packageKey] = $packageDirectories;
+                }
             }
         }
 
@@ -98,11 +101,15 @@ protected function createStorageObject($resourcePathAndFilename, FlowPackageInte
 
         $object = new StorageObject();
         $object->setFilename($pathInfo['basename']);
-        $object->setSha1(sha1_file($resourcePathAndFilename));
-        $object->setFileSize(filesize($resourcePathAndFilename));
-        if (isset($pathInfo['dirname'])) {
-            $object->setRelativePublicationPath($this->prepareRelativePublicationPath($pathInfo['dirname'], $resourcePackage->getPackageKey(), $resourcePackage->getResourcesPath()));
+        $sha1 = sha1_file($resourcePathAndFilename);
+        if ($sha1 !== false) {
+            $object->setSha1($sha1);
+        }
+        $fileSize = filesize($resourcePathAndFilename);
+        if ($fileSize !== false) {
+            $object->setFileSize($fileSize);
         }
+        $object->setRelativePublicationPath($this->prepareRelativePublicationPath($pathInfo['dirname'], $resourcePackage->getPackageKey(), $resourcePackage->getResourcesPath()));
         $object->setStream(function () use ($resourcePathAndFilename) {
             return fopen($resourcePathAndFilename, 'r');
         });
diff --git a/Neos.Flow/Classes/ResourceManagement/Storage/StorageObject.php b/Neos.Flow/Classes/ResourceManagement/Storage/StorageObject.php
index 40dc365534..53d37a923e 100644
--- a/Neos.Flow/Classes/ResourceManagement/Storage/StorageObject.php
+++ b/Neos.Flow/Classes/ResourceManagement/Storage/StorageObject.php
@@ -98,7 +98,7 @@ public function getMediaType()
     public function setFilename($filename)
     {
         $pathInfo = UnicodeFunctions::pathinfo($filename);
-        $extension = (isset($pathInfo['extension']) ? '.' . strtolower($pathInfo['extension']) : '');
+        $extension = '.' . strtolower($pathInfo['extension']);
         $this->filename = $pathInfo['filename'] . $extension;
         $this->mediaType = MediaTypes::getMediaTypeFromFilename($this->filename);
     }
@@ -201,7 +201,11 @@ public function setStream($stream)
     public function getStream()
     {
         if ($this->stream instanceof \Closure) {
-            $this->stream = $this->stream->__invoke();
+            $resource = $this->stream->__invoke();
+            if (!is_resource($resource)) {
+                throw new \Exception('Failed to resolve resource from closure', 1743962813);
+            }
+            $this->stream = $resource;
         }
         if (is_resource($this->stream)) {
             $meta = stream_get_meta_data($this->stream);
diff --git a/Neos.Flow/Classes/ResourceManagement/Storage/WritableFileSystemStorage.php b/Neos.Flow/Classes/ResourceManagement/Storage/WritableFileSystemStorage.php
index 1974e75a6c..f841a53aa8 100644
--- a/Neos.Flow/Classes/ResourceManagement/Storage/WritableFileSystemStorage.php
+++ b/Neos.Flow/Classes/ResourceManagement/Storage/WritableFileSystemStorage.php
@@ -57,12 +57,16 @@ public function importResource($source, $collectionName)
         if (is_resource($source)) {
             try {
                 $target = fopen($temporaryTargetPathAndFilename, 'wb');
+                if ($target === false) {
+                    throw new \Exception('Failed to open ' . $temporaryTargetPathAndFilename, 1743964877);
+                }
                 stream_copy_to_stream($source, $target);
                 fclose($target);
             } catch (\Exception $exception) {
                 throw new StorageException(sprintf('Could import the content stream to temporary file "%s".', $temporaryTargetPathAndFilename), 1380880079);
             }
         } else {
+            /** @var string $source */
             if (copy($source, $temporaryTargetPathAndFilename) === false) {
                 throw new StorageException(sprintf('Could not copy the file from "%s" to temporary file "%s".', $source, $temporaryTargetPathAndFilename), 1375198876);
             }
@@ -130,6 +134,9 @@ protected function importTemporaryFile($temporaryPathAndFileName, $collectionNam
     {
         $this->fixFilePermissions($temporaryPathAndFileName);
         $sha1Hash = sha1_file($temporaryPathAndFileName);
+        if ($sha1Hash === false) {
+            throw new \Exception('Failed to resolve sha1 hash for ' . $temporaryPathAndFileName);
+        }
         $targetPathAndFilename = $this->getStoragePathAndFilenameByHash($sha1Hash);
 
         if (!is_file($targetPathAndFilename)) {
@@ -139,7 +146,10 @@ protected function importTemporaryFile($temporaryPathAndFileName, $collectionNam
         }
 
         $resource = new PersistentResource();
-        $resource->setFileSize(filesize($targetPathAndFilename));
+        $fileSize = filesize($targetPathAndFilename);
+        if ($fileSize !== false) {
+            $resource->setFileSize($fileSize);
+        }
         $resource->setCollectionName($collectionName);
         $resource->setSha1($sha1Hash);
 
diff --git a/Neos.Flow/Classes/ResourceManagement/Streams/ResourceStreamWrapper.php b/Neos.Flow/Classes/ResourceManagement/Streams/ResourceStreamWrapper.php
index 752ce47558..6117b75326 100644
--- a/Neos.Flow/Classes/ResourceManagement/Streams/ResourceStreamWrapper.php
+++ b/Neos.Flow/Classes/ResourceManagement/Streams/ResourceStreamWrapper.php
@@ -88,7 +88,7 @@ public function closeDirectory()
      * This method is called in response to opendir().
      *
      * @param string $path Specifies the URL that was passed to opendir().
-     * @param int $options Whether or not to enforce safe_mode (0x04).
+     * @param int $options Whether to enforce safe_mode (0x04).
      * @return boolean true on success or false on failure.
      */
     public function openDirectory($path, $options)
@@ -97,7 +97,7 @@ public function openDirectory($path, $options)
         if (!is_string($resourceUriOrStream)) {
             return false;
         }
-        $handle = ($resourceUriOrStream !== false) ? opendir($resourceUriOrStream) : false;
+        $handle = opendir($resourceUriOrStream);
         if ($handle !== false) {
             $this->handle = $handle;
             return true;
@@ -110,7 +110,7 @@ public function openDirectory($path, $options)
      *
      * This method is called in response to readdir().
      *
-     * @return string Should return string representing the next filename, or false if there is no next file.
+     * @return string|false Should return string representing the next filename, or false if there is no next file.
      */
     public function readDirectory()
     {
@@ -148,7 +148,7 @@ public function makeDirectory($path, $mode, $options)
     {
         $resourceUriOrStream = $this->evaluateResourcePath($path, false);
         if (is_string($resourceUriOrStream)) {
-            return mkdir($resourceUriOrStream, $mode, $options&STREAM_MKDIR_RECURSIVE);
+            return mkdir($resourceUriOrStream, $mode, (bool)($options&STREAM_MKDIR_RECURSIVE));
         }
         return false;
     }
@@ -309,10 +309,11 @@ public function open($path, $mode, $options, &$openedPathAndFilename)
             $this->handle = $resourceUriOrStream;
             return true;
         }
-
+        /** @var string|false $resourceUriOrStream */
         $handle = ($resourceUriOrStream !== false) ? fopen($resourceUriOrStream, $mode) : false;
         if ($handle !== false) {
             $this->handle = $handle;
+            /** @var string $resourceUriOrStream */
             $openedPathAndFilename = $resourceUriOrStream;
             return true;
         }
@@ -328,10 +329,13 @@ public function open($path, $mode, $options, &$openedPathAndFilename)
      * number of bytes that were successfully read).
      *
      * @param integer $count How many bytes of data from the current position should be returned.
-     * @return string If there are less than count bytes available, return as many as are available. If no more data is available, return either false or an empty string.
+     * @return string|false If there are less than count bytes available, return as many as are available. If no more data is available, return either false or an empty string.
      */
     public function read($count)
     {
+        if ($count < 1) {
+            throw new \Exception('Cannot read less than one byte', 1743964166);
+        }
         return fread($this->handle, $count);
     }
 
@@ -392,7 +396,7 @@ public function setOption($option, $argument1, $argument2)
      *
      * This method is called in response to ftell().
      *
-     * @return int Should return the current position of the stream.
+     * @return int|false Should return the current position of the stream.
      */
     public function tell()
     {
@@ -411,7 +415,7 @@ public function tell()
      * bytes that were successfully written.
      *
      * @param string $data Should be stored into the underlying stream.
-     * @return int Should return the number of bytes that were successfully stored, or 0 if none could be stored.
+     * @return int|false Should return the number of bytes that were successfully stored, or 0 if none could be stored.
      */
     public function write($data)
     {
@@ -441,7 +445,7 @@ public function unlink($path)
      *
      * This method is called in response to fstat().
      *
-     * @return array See http://php.net/stat
+     * @return array<int|string, int>|false See http://php.net/stat
      */
     public function resourceStat()
     {
@@ -472,14 +476,18 @@ public function resourceStat()
      *
      * @param string $path The file path or URL to stat. Note that in the case of a URL, it must be a :// delimited URL. Other URL forms are not supported.
      * @param integer $flags Holds additional flags set by the streams API.
-     * @return array Should return as many elements as stat() does. Unknown or unavailable values should be set to a rational value (usually 0).
+     * @return array<int|string, int>|false Should return as many elements as stat() does. Unknown or unavailable values should be set to a rational value (usually 0).
      */
     public function pathStat($path, $flags)
     {
         $evaluatedResourcePath = $this->evaluateResourcePath($path);
+        if ($evaluatedResourcePath === false) {
+            return false;
+        }
         if (is_resource($evaluatedResourcePath)) {
             return @fstat($evaluatedResourcePath);
         }
+        /** @var string $evaluatedResourcePath */
         return @stat($evaluatedResourcePath);
     }
 
@@ -489,7 +497,7 @@ public function pathStat($path, $flags)
      *
      * @param string $requestedPath
      * @param boolean $checkForExistence Whether a (non-hash) path should be checked for existence before being returned
-     * @return mixed The full path and filename or false if the file doesn't exist
+     * @return string|resource|false The full path and filename or false if the file doesn't exist
      * @throws \InvalidArgumentException|ResourceException
      */
     protected function evaluateResourcePath($requestedPath, $checkForExistence = true)
@@ -507,7 +515,7 @@ protected function evaluateResourcePath($requestedPath, $checkForExistence = tru
 
         if (strpos($resourceUriWithoutScheme, '/') === false && preg_match('/^[0-9a-f]{40}$/i', $resourceUriWithoutScheme) === 1) {
             $resource = $this->resourceManager->getResourceBySha1($resourceUriWithoutScheme);
-            return $this->resourceManager->getStreamByResource($resource);
+            return $resource ? $this->resourceManager->getStreamByResource($resource) : false;
         }
 
         list($packageName, $path) = explode('/', $resourceUriWithoutScheme, 2);
diff --git a/Neos.Flow/Classes/ResourceManagement/Streams/StreamWrapperAdapter.php b/Neos.Flow/Classes/ResourceManagement/Streams/StreamWrapperAdapter.php
index adec60d7fc..a75a876278 100644
--- a/Neos.Flow/Classes/ResourceManagement/Streams/StreamWrapperAdapter.php
+++ b/Neos.Flow/Classes/ResourceManagement/Streams/StreamWrapperAdapter.php
@@ -28,7 +28,7 @@
 class StreamWrapperAdapter
 {
     /**
-     * @var array
+     * @var array<string,class-string<StreamWrapperInterface>> indexed by scheme
      */
     protected static $registeredStreamWrappers = [];
 
@@ -51,7 +51,6 @@ class StreamWrapperAdapter
     public static function initializeStreamWrapper($objectManager)
     {
         $streamWrapperClassNames = static::getStreamWrapperImplementationClassNames($objectManager);
-        /** @var StreamWrapperInterface $streamWrapperClassName */
         foreach ($streamWrapperClassNames as $streamWrapperClassName) {
             $scheme = $streamWrapperClassName::getScheme();
             if (in_array($scheme, stream_get_wrappers())) {
@@ -67,7 +66,7 @@ public static function initializeStreamWrapper($objectManager)
      * earlier ones without warning.
      *
      * @param string $scheme
-     * @param string $objectName
+     * @param class-string<StreamWrapperInterface> $objectName
      * @return void
      */
     public static function registerStreamWrapper($scheme, $objectName)
@@ -78,7 +77,7 @@ public static function registerStreamWrapper($scheme, $objectName)
     /**
      * Returns the stream wrappers registered with this class.
      *
-     * @return array
+     * @return array<string,class-string<StreamWrapperInterface>> indexed by scheme
      */
     public static function getRegisteredStreamWrappers()
     {
@@ -226,7 +225,7 @@ public function rmdir($path, $options)
      * This method is called in response to stream_select().
      *
      * @param integer $cast_as Can be STREAM_CAST_FOR_SELECT when stream_select() is calling stream_cast() or STREAM_CAST_AS_STREAM when stream_cast() is called for other uses.
-     * @return resource Should return the underlying stream resource used by the wrapper, or false.
+     * @return resource|false Should return the underlying stream resource used by the wrapper, or false.
      */
     public function stream_cast($cast_as)
     {
@@ -401,7 +400,7 @@ public function stream_set_option($option, $arg1, $arg2)
      *
      * This method is called in response to fstat().
      *
-     * @return array See http://php.net/stat
+     * @return array<string,int> See http://php.net/stat
      */
     public function stream_stat()
     {
@@ -476,7 +475,7 @@ public function unlink($path)
      *
      * @param string $path The file path or URL to stat. Note that in the case of a URL, it must be a :// delimited URL. Other URL forms are not supported.
      * @param integer $flags Holds additional flags set by the streams API.
-     * @return array Should return as many elements as stat() does. Unknown or unavailable values should be set to a rational value (usually 0).
+     * @return array<int|string, int>|false Should return as many elements as stat() does. Unknown or unavailable values should be set to a rational value (usually 0).
      */
     public function url_stat($path, $flags)
     {
@@ -488,7 +487,7 @@ public function url_stat($path, $flags)
      * Returns all class names implementing the StreamWrapperInterface.
      *
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of stream wrapper implementations
+     * @return array<class-string<StreamWrapperInterface>> Array of stream wrapper implementations
      * @Flow\CompileStatic
      */
     public static function getStreamWrapperImplementationClassNames(ObjectManagerInterface $objectManager)
diff --git a/Neos.Flow/Classes/ResourceManagement/Streams/StreamWrapperInterface.php b/Neos.Flow/Classes/ResourceManagement/Streams/StreamWrapperInterface.php
index 13365e92c6..11e91d18a1 100644
--- a/Neos.Flow/Classes/ResourceManagement/Streams/StreamWrapperInterface.php
+++ b/Neos.Flow/Classes/ResourceManagement/Streams/StreamWrapperInterface.php
@@ -335,7 +335,7 @@ public function unlink($path);
      *
      * This method is called in response to fstat().
      *
-     * @return array See http://php.net/stat
+     * @return array<string,int> See http://php.net/stat
      * @api
      */
     public function resourceStat();
@@ -359,7 +359,7 @@ public function resourceStat();
      *
      * @param string $path The file path or URL to stat. Note that in the case of a URL, it must be a :// delimited URL. Other URL forms are not supported.
      * @param integer $flags Holds additional flags set by the streams API.
-     * @return array Should return as many elements as stat() does. Unknown or unavailable values should be set to a rational value (usually 0).
+     * @return array<int|string, int>|false Should return as many elements as stat() does. Unknown or unavailable values should be set to a rational value (usually 0).
      * @api
      */
     public function pathStat($path, $flags);
diff --git a/Neos.Flow/Classes/ResourceManagement/Target/FileSystemSymlinkTarget.php b/Neos.Flow/Classes/ResourceManagement/Target/FileSystemSymlinkTarget.php
index f6e808cdbe..34a83aac88 100644
--- a/Neos.Flow/Classes/ResourceManagement/Target/FileSystemSymlinkTarget.php
+++ b/Neos.Flow/Classes/ResourceManagement/Target/FileSystemSymlinkTarget.php
@@ -62,7 +62,7 @@ protected function publishFile($sourceStream, $relativeTargetPathAndFilename)
     {
         $extension = strtolower(pathinfo($relativeTargetPathAndFilename, PATHINFO_EXTENSION));
         if ($extension !== '' && array_key_exists($extension, $this->excludedExtensions) && $this->excludedExtensions[$extension] === true) {
-            throw new TargetException(sprintf('Could not publish "%s" into resource publishing target "%s" because the filename extension "%s" is excluded.', $sourceStream, $this->name, $extension), 1447152230);
+            throw new TargetException(sprintf('Could not publish resource into publishing target "%s" because the filename extension "%s" is excluded.', $this->name, $extension), 1447152230);
         }
 
         $streamMetaData = stream_get_meta_data($sourceStream);
@@ -151,6 +151,9 @@ protected function setOption($key, $value)
         return parent::setOption($key, $value);
     }
 
+    /**
+     * @return array{0: bool, 1: ?\Exception}
+     */
     private function publish(string $targetPathAndFilename, string $sourcePathAndFilename): array
     {
         $exception = null;
diff --git a/Neos.Flow/Classes/ResourceManagement/Target/FileSystemTarget.php b/Neos.Flow/Classes/ResourceManagement/Target/FileSystemTarget.php
index f30d54274b..3d6c8bf149 100644
--- a/Neos.Flow/Classes/ResourceManagement/Target/FileSystemTarget.php
+++ b/Neos.Flow/Classes/ResourceManagement/Target/FileSystemTarget.php
@@ -33,7 +33,7 @@
 class FileSystemTarget implements TargetInterface
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $options = [];
 
@@ -83,7 +83,7 @@ class FileSystemTarget implements TargetInterface
     /**
      * A list of extensions that are excluded and must not be published by this target.
      *
-     * @var array
+     * @var array<string,bool>
      */
     protected $excludedExtensions = [];
 
@@ -115,7 +115,7 @@ class FileSystemTarget implements TargetInterface
      * Constructor
      *
      * @param string $name Name of this target instance, according to the resource settings
-     * @param array $options Options for this target
+     * @param array<string,mixed> $options Options for this target
      */
     public function __construct($name, array $options = [])
     {
@@ -217,8 +217,9 @@ public function publishCollection(CollectionInterface $collection)
         $this->checkAndRemovePackageSymlinks($storage);
         $iteration = 0;
         foreach ($collection->getObjects() as $object) {
-            $sourceStream = $object->getStream();
-            if ($sourceStream === false) {
+            try {
+                $sourceStream = $object->getStream();
+            } catch (\Exception) {
                 $this->handleMissingData($object, $collection);
                 continue;
             }
@@ -255,7 +256,7 @@ public function publishResource(PersistentResource $resource, CollectionInterfac
      * @param ResourceMetaDataInterface $resource
      * @param CollectionInterface $collection
      */
-    protected function handleMissingData(ResourceMetaDataInterface $resource, CollectionInterface $collection)
+    protected function handleMissingData(ResourceMetaDataInterface $resource, CollectionInterface $collection): void
     {
         $message = sprintf('Could not publish resource %s with SHA1 hash %s of collection %s because there seems to be no corresponding data in the storage.', $resource->getFilename(), $resource->getSha1(), $collection->getName());
         $this->messageCollector->append($message);
@@ -323,16 +324,16 @@ protected function encodeRelativePathAndFilenameForUri($relativePathAndFilename)
     protected function publishFile($sourceStream, $relativeTargetPathAndFilename)
     {
         $pathInfo = UnicodeFunctions::pathinfo($relativeTargetPathAndFilename);
-        if (isset($pathInfo['extension']) && array_key_exists(strtolower($pathInfo['extension']), $this->excludedExtensions) && $this->excludedExtensions[strtolower($pathInfo['extension'])] === true) {
-            throw new TargetException(sprintf('Could not publish "%s" into resource publishing target "%s" because the filename extension "%s" is excluded.', $sourceStream, $this->name, strtolower($pathInfo['extension'])), 1447148472);
+        if (array_key_exists(strtolower($pathInfo['extension']), $this->excludedExtensions) && $this->excludedExtensions[strtolower($pathInfo['extension'])] === true) {
+            throw new TargetException(sprintf('Could not publish resource into publishing target "%s" because the filename extension "%s" is excluded.', $this->name, strtolower($pathInfo['extension'])), 1447148472);
         }
 
         $targetPathAndFilename = $this->path . $relativeTargetPathAndFilename;
         $streamMetaData = stream_get_meta_data($sourceStream);
-        $sourcePathAndFilename = $streamMetaData['uri'] ?? null;
+        $sourcePathAndFilename = $streamMetaData['uri'];
 
         if (@fstat($sourceStream) === false) {
-            throw new TargetException(sprintf('Could not publish "%s" into resource publishing target "%s" because the source file is not accessible (file stat failed).', $sourceStream, $this->name), 1375258499);
+            throw new TargetException(sprintf('Could not publish resource into publishing target "%s" because the source file is not accessible (file stat failed).', $this->name), 1375258499);
         }
 
         // If you switch from FileSystemSymlinkTarget than we need to remove the symlink before trying to write the file
@@ -346,7 +347,7 @@ protected function publishFile($sourceStream, $relativeTargetPathAndFilename)
         }
 
         if (!is_writable(dirname($targetPathAndFilename))) {
-            throw new Exception(sprintf('Could not publish "%s" into resource publishing target "%s" because the target file "%s" is not writable.', $sourceStream, $this->name, $targetPathAndFilename), 1428917322);
+            throw new Exception(sprintf('Could not publish resource into publishing target "%s" because the target file "%s" is not writable.', $this->name, $targetPathAndFilename), 1428917322);
         }
 
         try {
@@ -361,7 +362,7 @@ protected function publishFile($sourceStream, $relativeTargetPathAndFilename)
             $result = false;
         }
         if ($result === false) {
-            throw new TargetException(sprintf('Could not publish "%s" into resource publishing target "%s" because the source file could not be copied to the target location "%s".', $sourceStream, $this->name, $targetPathAndFilename), 1375258399, ($exception ?? null));
+            throw new TargetException(sprintf('Could not publish resource into publishing target "%s" because the source file could not be copied to the target location "%s".', $this->name, $targetPathAndFilename), 1375258399, ($exception ?? null));
         }
 
         $this->logger->debug(sprintf('FileSystemTarget: Published file. (target: %s, file: %s)', $this->name, $relativeTargetPathAndFilename));
diff --git a/Neos.Flow/Classes/Security/Account.php b/Neos.Flow/Classes/Security/Account.php
index 59afe04d2f..edd33c6b55 100644
--- a/Neos.Flow/Classes/Security/Account.php
+++ b/Neos.Flow/Classes/Security/Account.php
@@ -55,7 +55,7 @@ class Account
     protected $creationDate;
 
     /**
-     * @var \DateTime
+     * @var \DateTime|null
      * @ORM\Column(nullable=true)
      */
     protected $expirationDate;
@@ -73,7 +73,7 @@ class Account
     protected $failedAuthenticationCount;
 
     /**
-     * @var array of strings
+     * @var array<string>
      * @ORM\Column(type="simple_array", nullable=true)
      */
     protected $roleIdentifiers = [];
@@ -225,9 +225,6 @@ public function setRoles(array $roles)
         $this->roleIdentifiers = [];
         $this->roles = [];
         foreach ($roles as $role) {
-            if (!$role instanceof Role) {
-                throw new \InvalidArgumentException(sprintf('setRoles() only accepts an array of %s instances, given: "%s"', Role::class, gettype($role)), 1397125997);
-            }
             $this->addRole($role);
         }
     }
@@ -310,7 +307,7 @@ public function getExpirationDate()
     /**
      * Sets the date on which this account will become inactive
      *
-     * @param \DateTime $expirationDate
+     * @param ?\DateTime $expirationDate
      * @return void
      * @api
      */
diff --git a/Neos.Flow/Classes/Security/AccountFactory.php b/Neos.Flow/Classes/Security/AccountFactory.php
index e90acf5f0f..69a62229ff 100644
--- a/Neos.Flow/Classes/Security/AccountFactory.php
+++ b/Neos.Flow/Classes/Security/AccountFactory.php
@@ -37,7 +37,7 @@ class AccountFactory
      *
      * @param string $identifier Identifier of the account, must be unique
      * @param string $password The clear text password
-     * @param array $roleIdentifiers Optionally an array of role identifiers to assign to the new account
+     * @param array<string> $roleIdentifiers Optionally an array of role identifiers to assign to the new account
      * @param string $authenticationProviderName Optional name of the authentication provider the account is affiliated with
      * @param string $passwordHashingStrategy Optional password hashing strategy to use for the password
      * @return Account A new account, not yet added to the account repository
diff --git a/Neos.Flow/Classes/Security/AccountRepository.php b/Neos.Flow/Classes/Security/AccountRepository.php
index b305695968..293274335e 100644
--- a/Neos.Flow/Classes/Security/AccountRepository.php
+++ b/Neos.Flow/Classes/Security/AccountRepository.php
@@ -30,7 +30,7 @@ class AccountRepository extends Repository
     const ENTITY_CLASSNAME = Account::class;
 
     /**
-     * @var array
+     * @var array<string,QueryInterface::ORDER_ASCENDING|QueryInterface::ORDER_DESCENDING>
      */
     protected $defaultOrderings = ['creationDate' => QueryInterface::ORDER_DESCENDING];
 
@@ -51,6 +51,9 @@ class AccountRepository extends Repository
      */
     public function remove($object): void
     {
+        if (!($object instanceof Account)) {
+            throw new \InvalidArgumentException('Can only remove account objects.', 1743961393);
+        }
         parent::remove($object);
 
         // destroy the sessions for the account to be removed
@@ -67,12 +70,14 @@ public function remove($object): void
     public function findByAccountIdentifierAndAuthenticationProviderName($accountIdentifier, $authenticationProviderName)
     {
         $query = $this->createQuery();
-        return $query->matching(
+        $result = $query->matching(
             $query->logicalAnd(
                 $query->equals('accountIdentifier', $accountIdentifier),
                 $query->equals('authenticationProviderName', $authenticationProviderName)
             )
         )->execute()->getFirst();
+
+        return $result instanceof Account ? $result : null;
     }
 
     /**
@@ -85,7 +90,7 @@ public function findByAccountIdentifierAndAuthenticationProviderName($accountIde
     public function findActiveByAccountIdentifierAndAuthenticationProviderName($accountIdentifier, $authenticationProviderName)
     {
         $query = $this->createQuery();
-        return $query->matching(
+        $result = $query->matching(
             $query->logicalAnd(
                 $query->equals('accountIdentifier', $accountIdentifier),
                 $query->equals('authenticationProviderName', $authenticationProviderName),
@@ -95,5 +100,7 @@ public function findActiveByAccountIdentifierAndAuthenticationProviderName($acco
                 )
             )
         )->execute()->getFirst();
+
+        return $result instanceof Account ? $result : null;
     }
 }
diff --git a/Neos.Flow/Classes/Security/Aspect/LoggingAspect.php b/Neos.Flow/Classes/Security/Aspect/LoggingAspect.php
index e85afc9ac1..ae4271ee8c 100644
--- a/Neos.Flow/Classes/Security/Aspect/LoggingAspect.php
+++ b/Neos.Flow/Classes/Security/Aspect/LoggingAspect.php
@@ -100,9 +100,9 @@ public function logManagerLogout(JoinPointInterface $joinPoint)
     }
 
     /**
-     * @param array $collectedIdentifiers
+     * @param array<string> $collectedIdentifiers
      * @param TokenInterface $token
-     * @return array
+     * @return array<string>
      */
     protected function reduceTokenToAccountIdentifier(array $collectedIdentifiers, TokenInterface $token): array
     {
@@ -170,7 +170,7 @@ public function logPrivilegeAccessDecisions(JoinPointInterface $joinPoint)
 
     /**
      * @param JoinPointInterface $joinPoint
-     * @return array
+     * @return array<string,array{packageKey: string, className: string, methodName: string}>
      */
     protected function getLogEnvironmentFromJoinPoint(JoinPointInterface $joinPoint): array
     {
diff --git a/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderInterface.php b/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderInterface.php
index 965c39a1d1..8f3dbf3b6a 100644
--- a/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderInterface.php
+++ b/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderInterface.php
@@ -21,7 +21,7 @@ interface AuthenticationProviderInterface
      * Constructs an instance with the given name and options.
      *
      * @param string $name
-     * @param array $options
+     * @param array<mixed> $options
      * @return self
      */
     public static function create(string $name, array $options);
@@ -37,7 +37,7 @@ public function canAuthenticate(TokenInterface $token);
     /**
      * Returns the classnames of the tokens this provider is responsible for.
      *
-     * @return array The classname of the token this provider is responsible for
+     * @return array<class-string<TokenInterface>> The classname of the token this provider is responsible for
      */
     public function getTokenClassNames();
 
diff --git a/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderManager.php b/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderManager.php
index ed40991eab..5746d2c08f 100644
--- a/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderManager.php
+++ b/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderManager.php
@@ -51,7 +51,7 @@ class AuthenticationProviderManager implements AuthenticationManagerInterface
      * Injected configuration for providers.
      * Will be null'd again after building the object instances.
      *
-     * @var array|null
+     * @var array<mixed>|null
      */
     protected $providerConfigurations;
 
@@ -81,7 +81,7 @@ public function __construct(TokenAndProviderFactoryInterface $tokenAndProviderFa
     /**
      * Inject the settings and does a fresh build of tokens based on the injected settings
      *
-     * @param array $settings The settings
+     * @param array<string,mixed> $settings The settings
      * @return void
      * @throws Exception
      */
@@ -206,7 +206,10 @@ public function isAuthenticated(): bool
             } catch (AuthenticationRequiredException $exception) {
             }
         }
-        return $this->isAuthenticated;
+
+        return $this->isAuthenticated !== null
+            ? $this->isAuthenticated
+            : false;
     }
 
     /**
diff --git a/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderResolver.php b/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderResolver.php
index d04def1887..30bf153f7c 100644
--- a/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderResolver.php
+++ b/Neos.Flow/Classes/Security/Authentication/AuthenticationProviderResolver.php
@@ -47,12 +47,12 @@ public function __construct(ObjectManagerInterface $objectManager)
     public function resolveProviderClass($providerName)
     {
         $className = $this->objectManager->getClassNameByObjectName($providerName);
-        if ($className !== false) {
+        if ($className !== false && is_subclass_of($className, AuthenticationProviderInterface::class)) {
             return $className;
         }
 
         $className = $this->objectManager->getClassNameByObjectName('Neos\Flow\Security\Authentication\Provider\\' . $providerName);
-        if ($className !== false) {
+        if ($className !== false && is_subclass_of($className, AuthenticationProviderInterface::class)) {
             return $className;
         }
 
diff --git a/Neos.Flow/Classes/Security/Authentication/Controller/AbstractAuthenticationController.php b/Neos.Flow/Classes/Security/Authentication/Controller/AbstractAuthenticationController.php
index 0c5fe443a5..7ac7f4aae6 100644
--- a/Neos.Flow/Classes/Security/Authentication/Controller/AbstractAuthenticationController.php
+++ b/Neos.Flow/Classes/Security/Authentication/Controller/AbstractAuthenticationController.php
@@ -85,7 +85,11 @@ public function authenticateAction()
 
         if (!$this->authenticationManager->isAuthenticated()) {
             $this->onAuthenticationFailure($authenticationException);
-            return call_user_func([$this, $this->errorMethodName]);
+            $callable = [$this, $this->errorMethodName];
+            if (!is_callable($callable)) {
+                throw new \Exception('Invalid error method ' . $this->errorMethodName, 1743955562);
+            }
+            return call_user_func($callable);
         }
 
         $storedRequest = $this->securityContext->getInterceptedRequest();
diff --git a/Neos.Flow/Classes/Security/Authentication/EntryPoint/AbstractEntryPoint.php b/Neos.Flow/Classes/Security/Authentication/EntryPoint/AbstractEntryPoint.php
index f11c1d5e60..c609acbd56 100644
--- a/Neos.Flow/Classes/Security/Authentication/EntryPoint/AbstractEntryPoint.php
+++ b/Neos.Flow/Classes/Security/Authentication/EntryPoint/AbstractEntryPoint.php
@@ -21,14 +21,14 @@ abstract class AbstractEntryPoint implements EntryPointInterface
     /**
      * The configurations options
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $options = [];
 
     /**
      * Sets the options array
      *
-     * @param array $options An array of configuration options
+     * @param array<mixed> $options An array of configuration options
      * @return void
      */
     public function setOptions(array $options)
@@ -39,7 +39,7 @@ public function setOptions(array $options)
     /**
      * Returns the options array
      *
-     * @return array The configuration options of this entry point
+     * @return array<mixed> The configuration options of this entry point
      */
     public function getOptions()
     {
diff --git a/Neos.Flow/Classes/Security/Authentication/EntryPoint/WebRedirect.php b/Neos.Flow/Classes/Security/Authentication/EntryPoint/WebRedirect.php
index a37757f4b0..b0aacac10c 100644
--- a/Neos.Flow/Classes/Security/Authentication/EntryPoint/WebRedirect.php
+++ b/Neos.Flow/Classes/Security/Authentication/EntryPoint/WebRedirect.php
@@ -75,7 +75,7 @@ public function startAuthentication(ServerRequestInterface $request, ResponseInt
     }
 
     /**
-     * @param array $routeValues
+     * @param array<string,mixed> $routeValues
      * @param ServerRequestInterface $request
      * @return string
      * @throws \Neos\Flow\Mvc\Routing\Exception\MissingActionNameException
@@ -96,7 +96,7 @@ protected function generateUriFromRouteValues(array $routeValues, ServerRequestI
      * Returns the entry $key from the array $routeValues removing the original array item.
      * If $key does not exist, NULL is returned.
      *
-     * @param array $routeValues
+     * @param array<string,mixed> $routeValues
      * @param string $key
      * @return mixed the specified route value or NULL if it is not set
      */
diff --git a/Neos.Flow/Classes/Security/Authentication/EntryPointInterface.php b/Neos.Flow/Classes/Security/Authentication/EntryPointInterface.php
index 9fba7eb5ac..3db795974b 100644
--- a/Neos.Flow/Classes/Security/Authentication/EntryPointInterface.php
+++ b/Neos.Flow/Classes/Security/Authentication/EntryPointInterface.php
@@ -22,7 +22,7 @@ interface EntryPointInterface
     /**
      * Sets the options array
      *
-     * @param array $options An array of configuration options
+     * @param array<mixed> $options An array of configuration options
      * @return void
      */
     public function setOptions(array $options);
@@ -30,7 +30,7 @@ public function setOptions(array $options);
     /**
      * Returns the options array
      *
-     * @return array An array of configuration options
+     * @return array<mixed> An array of configuration options
      */
     public function getOptions();
 
diff --git a/Neos.Flow/Classes/Security/Authentication/Provider/AbstractProvider.php b/Neos.Flow/Classes/Security/Authentication/Provider/AbstractProvider.php
index 7ddcac499c..c518e7bd8c 100644
--- a/Neos.Flow/Classes/Security/Authentication/Provider/AbstractProvider.php
+++ b/Neos.Flow/Classes/Security/Authentication/Provider/AbstractProvider.php
@@ -26,7 +26,7 @@ abstract class AbstractProvider implements AuthenticationProviderInterface
     protected $name;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $options = [];
 
@@ -34,7 +34,7 @@ abstract class AbstractProvider implements AuthenticationProviderInterface
      * Factory method
      *
      * @param string $name
-     * @param array $options
+     * @param array<mixed> $options
      * @return AuthenticationProviderInterface
      * @api
      */
@@ -47,7 +47,7 @@ public static function create(string $name, array $options)
      * Protected constructor, see create method
      *
      * @param string $name The name of this authentication provider
-     * @param array $options Additional configuration options
+     * @param array<mixed> $options Additional configuration options
      * @see create
      */
     protected function __construct($name, array $options = [])
diff --git a/Neos.Flow/Classes/Security/Authentication/Provider/FileBasedSimpleKeyProvider.php b/Neos.Flow/Classes/Security/Authentication/Provider/FileBasedSimpleKeyProvider.php
index 5f92aa376a..f256d13b8a 100644
--- a/Neos.Flow/Classes/Security/Authentication/Provider/FileBasedSimpleKeyProvider.php
+++ b/Neos.Flow/Classes/Security/Authentication/Provider/FileBasedSimpleKeyProvider.php
@@ -66,7 +66,7 @@ class FileBasedSimpleKeyProvider extends AbstractProvider
     /**
      * Returns the class names of the tokens this provider can authenticate.
      *
-     * @return array
+     * @return array<class-string<TokenInterface>>
      */
     public function getTokenClassNames()
     {
@@ -106,7 +106,8 @@ public function authenticate(TokenInterface $authenticationToken)
      */
     protected function validateCredentials(PasswordTokenInterface $authenticationToken): void
     {
-        if (!$this->hashService->validatePassword($authenticationToken->getPassword(), $this->fileBasedSimpleKeyService->getKey($this->options['keyName']))) {
+        $key = $this->fileBasedSimpleKeyService->getKey($this->options['keyName']);
+        if (!$this->hashService->validatePassword($authenticationToken->getPassword(), $key)) {
             $authenticationToken->setAuthenticationStatus(TokenInterface::WRONG_CREDENTIALS);
             return;
         }
diff --git a/Neos.Flow/Classes/Security/Authentication/Provider/PersistedUsernamePasswordProvider.php b/Neos.Flow/Classes/Security/Authentication/Provider/PersistedUsernamePasswordProvider.php
index 4c14105b59..7861c532bc 100644
--- a/Neos.Flow/Classes/Security/Authentication/Provider/PersistedUsernamePasswordProvider.php
+++ b/Neos.Flow/Classes/Security/Authentication/Provider/PersistedUsernamePasswordProvider.php
@@ -62,7 +62,7 @@ class PersistedUsernamePasswordProvider extends AbstractProvider
     /**
      * Returns the class names of the tokens this provider can authenticate.
      *
-     * @return array
+     * @return array<class-string<TokenInterface>>
      */
     public function getTokenClassNames()
     {
diff --git a/Neos.Flow/Classes/Security/Authentication/Provider/TestingProvider.php b/Neos.Flow/Classes/Security/Authentication/Provider/TestingProvider.php
index cff0310b51..7fc46ea159 100644
--- a/Neos.Flow/Classes/Security/Authentication/Provider/TestingProvider.php
+++ b/Neos.Flow/Classes/Security/Authentication/Provider/TestingProvider.php
@@ -34,7 +34,7 @@ class TestingProvider extends AbstractProvider
     /**
      * Returns the class names of the tokens this provider can authenticate.
      *
-     * @return array
+     * @return array<class-string<TokenInterface>>
      */
     public function getTokenClassNames()
     {
diff --git a/Neos.Flow/Classes/Security/Authentication/Token/AbstractToken.php b/Neos.Flow/Classes/Security/Authentication/Token/AbstractToken.php
index 42900ce9f6..6e232467dd 100644
--- a/Neos.Flow/Classes/Security/Authentication/Token/AbstractToken.php
+++ b/Neos.Flow/Classes/Security/Authentication/Token/AbstractToken.php
@@ -36,18 +36,18 @@ abstract class AbstractToken implements TokenInterface
 
     /**
      * The credentials submitted by the client
-     * @var array
+     * @var array<mixed>
      * @Flow\Transient
      */
     protected $credentials = [];
 
     /**
-     * @var Account
+     * @var ?Account
      */
     protected $account;
 
     /**
-     * @var array
+     * @var array<RequestPatternInterface>
      */
     protected $requestPatterns = [];
 
@@ -59,14 +59,14 @@ abstract class AbstractToken implements TokenInterface
 
     /**
      * Token options
-     * @var array
+     * @var array<mixed>
      */
     protected $options;
 
     /**
      * Build an instance of this token, potentially passing it options that can be configured via `tokenOptions`
      *
-     * @param array|null $options
+     * @param array<mixed>|null $options
      */
     public function __construct(?array $options = null)
     {
@@ -118,7 +118,7 @@ public function setAuthenticationEntryPoint(EntryPointInterface $entryPoint)
     /**
      * Returns the configured authentication entry point, NULL if none is available
      *
-     * @return EntryPointInterface The configured authentication entry point, NULL if none is available
+     * @return ?EntryPointInterface The configured authentication entry point, NULL if none is available
      */
     public function getAuthenticationEntryPoint()
     {
@@ -138,7 +138,7 @@ public function hasRequestPatterns()
     /**
      * Sets request patterns
      *
-     * @param array $requestPatterns Array of RequestPatternInterface to be set
+     * @param array<mixed> $requestPatterns Array of RequestPatternInterface to be set
      * @return void
      * @throws \InvalidArgumentException
      */
@@ -166,7 +166,7 @@ public function getRequestPatterns()
     /**
      * Returns the credentials (username and password) of this token.
      *
-     * @return array $credentials The needed credentials to authenticate this token
+     * @return array<mixed> $credentials The needed credentials to authenticate this token
      */
     public function getCredentials()
     {
@@ -176,7 +176,7 @@ public function getCredentials()
     /**
      * Returns the account if one is authenticated, NULL otherwise.
      *
-     * @return Account An account object
+     * @return ?Account An account object
      */
     public function getAccount()
     {
@@ -186,7 +186,7 @@ public function getAccount()
     /**
      * Set the (authenticated) account
      *
-     * @param Account $account An account object
+     * @param ?Account $account An account object
      * @return void
      */
     public function setAccount(?Account $account = null)
diff --git a/Neos.Flow/Classes/Security/Authentication/Token/BearerToken.php b/Neos.Flow/Classes/Security/Authentication/Token/BearerToken.php
index e51e3960ef..f09688a55a 100644
--- a/Neos.Flow/Classes/Security/Authentication/Token/BearerToken.php
+++ b/Neos.Flow/Classes/Security/Authentication/Token/BearerToken.php
@@ -30,7 +30,7 @@ class BearerToken extends AbstractToken implements SessionlessTokenInterface
 {
     /**
      * The password credentials
-     * @var array
+     * @var array{bearer: string}
      * @Flow\Transient
      */
     protected $credentials = ['bearer' => ''];
diff --git a/Neos.Flow/Classes/Security/Authentication/Token/PasswordToken.php b/Neos.Flow/Classes/Security/Authentication/Token/PasswordToken.php
index 90732a5ec1..2ecfaf9bbb 100644
--- a/Neos.Flow/Classes/Security/Authentication/Token/PasswordToken.php
+++ b/Neos.Flow/Classes/Security/Authentication/Token/PasswordToken.php
@@ -25,7 +25,7 @@ class PasswordToken extends AbstractToken implements PasswordTokenInterface
 
     /**
      * The password credentials
-     * @var array
+     * @var array{password: string,}
      * @Flow\Transient
      */
     protected $credentials = ['password' => ''];
@@ -60,7 +60,7 @@ public function updateCredentials(ActionRequest $actionRequest)
      */
     public function getPassword(): string
     {
-        return $this->credentials['password'] ?? '';
+        return $this->credentials['password'];
     }
 
     /**
diff --git a/Neos.Flow/Classes/Security/Authentication/Token/UsernamePassword.php b/Neos.Flow/Classes/Security/Authentication/Token/UsernamePassword.php
index 657ee6627d..5c93accc5e 100644
--- a/Neos.Flow/Classes/Security/Authentication/Token/UsernamePassword.php
+++ b/Neos.Flow/Classes/Security/Authentication/Token/UsernamePassword.php
@@ -26,7 +26,7 @@ class UsernamePassword extends AbstractToken implements UsernamePasswordTokenInt
 
     /**
      * The username/password credentials
-     * @var array
+     * @var array{username: string, password: string,}
      * @Flow\Transient
      */
     protected $credentials = ['username' => '', 'password' => ''];
@@ -78,7 +78,7 @@ public function updateCredentials(ActionRequest $actionRequest)
      */
     public function getUsername(): string
     {
-        return $this->credentials['username'] ?? '';
+        return $this->credentials['username'];
     }
 
     /**
@@ -86,7 +86,7 @@ public function getUsername(): string
      */
     public function getPassword(): string
     {
-        return $this->credentials['password'] ?? '';
+        return $this->credentials['password'];
     }
 
     /**
diff --git a/Neos.Flow/Classes/Security/Authentication/Token/UsernamePasswordHttpBasic.php b/Neos.Flow/Classes/Security/Authentication/Token/UsernamePasswordHttpBasic.php
index f8095bae8c..5342185072 100644
--- a/Neos.Flow/Classes/Security/Authentication/Token/UsernamePasswordHttpBasic.php
+++ b/Neos.Flow/Classes/Security/Authentication/Token/UsernamePasswordHttpBasic.php
@@ -28,7 +28,7 @@ class UsernamePasswordHttpBasic extends UsernamePassword implements SessionlessT
      */
     public function updateCredentials(ActionRequest $actionRequest)
     {
-        $this->credentials = ['username' => null, 'password' => null];
+        $this->credentials = ['username' => '', 'password' => ''];
         $this->authenticationStatus = self::NO_CREDENTIALS_GIVEN;
 
         $authorizationHeader = $actionRequest->getHttpRequest()->getHeaderLine('Authorization');
diff --git a/Neos.Flow/Classes/Security/Authentication/TokenAndProviderFactory.php b/Neos.Flow/Classes/Security/Authentication/TokenAndProviderFactory.php
index 4fe716176e..0314714fe5 100644
--- a/Neos.Flow/Classes/Security/Authentication/TokenAndProviderFactory.php
+++ b/Neos.Flow/Classes/Security/Authentication/TokenAndProviderFactory.php
@@ -40,7 +40,7 @@ class TokenAndProviderFactory implements TokenAndProviderFactoryInterface
     protected $tokens = [];
 
     /**
-     * @var array
+     * @var array<string,array<mixed>>
      */
     protected $providerConfigurations = [];
 
@@ -113,7 +113,7 @@ public function getProviders(): array
     /**
      * Inject the settings and does a fresh build of tokens based on the injected settings
      *
-     * @param array $settings The settings
+     * @param array<string,mixed> $settings The settings
      * @return void
      * @throws Exception
      */
@@ -151,14 +151,11 @@ protected function buildProvidersAndTokensFromConfiguration()
                 continue;
             }
 
-            if (!is_array($providerConfiguration) || !isset($providerConfiguration['provider'])) {
+            if (!isset($providerConfiguration['provider'])) {
                 throw new Exception\InvalidAuthenticationProviderException('The configured authentication provider "' . $providerName . '" needs a "provider" option!', 1248209521);
             }
 
             $providerObjectName = $this->providerResolver->resolveProviderClass((string)$providerConfiguration['provider']);
-            if ($providerObjectName === null) {
-                throw new Exception\InvalidAuthenticationProviderException('The configured authentication provider "' . $providerConfiguration['provider'] . '" could not be found!', 1237330453);
-            }
             $providerOptions = [];
             if (isset($providerConfiguration['providerOptions']) && is_array($providerConfiguration['providerOptions'])) {
                 $providerOptions = $providerConfiguration['providerOptions'];
@@ -175,7 +172,7 @@ protected function buildProvidersAndTokensFromConfiguration()
                 }
                 $tokenInstance = $this->objectManager->get($tokenClassName, $providerConfiguration['tokenOptions'] ?? []);
                 if (!$tokenInstance instanceof TokenInterface) {
-                    throw new Exception\InvalidAuthenticationProviderException(sprintf('The specified token is not an instance of %s but a %s. Please adjust the "token" configuration of the "%s" authentication provider', TokenInterface::class, is_object($tokenInstance) ? get_class($tokenInstance) : gettype($tokenInstance), $providerName), 1585921152);
+                    throw new Exception\InvalidAuthenticationProviderException(sprintf('The specified token is not an instance of %s but a %s. Please adjust the "token" configuration of the "%s" authentication provider', TokenInterface::class, get_class($tokenInstance), $providerName), 1585921152);
                 }
                 $tokenInstance->setAuthenticationProviderName($providerName);
                 $this->tokens[] = $tokenInstance;
@@ -225,7 +222,7 @@ protected function buildProvidersAndTokensFromConfiguration()
                     $entryPoint->setOptions($providerConfiguration['entryPointOptions']);
                 }
 
-                $tokenInstance->setAuthenticationEntryPoint($entryPoint);
+                $tokenInstance?->setAuthenticationEntryPoint($entryPoint);
             }
         }
 
diff --git a/Neos.Flow/Classes/Security/Authentication/TokenInterface.php b/Neos.Flow/Classes/Security/Authentication/TokenInterface.php
index 13b6eb868c..dff63f0388 100644
--- a/Neos.Flow/Classes/Security/Authentication/TokenInterface.php
+++ b/Neos.Flow/Classes/Security/Authentication/TokenInterface.php
@@ -88,7 +88,7 @@ public function setAuthenticationEntryPoint(EntryPointInterface $entryPoint);
     /**
      * Returns the configured authentication entry point, NULL if none is available
      *
-     * @return EntryPointInterface The configured authentication entry point, NULL if none is available
+     * @return ?EntryPointInterface The configured authentication entry point, NULL if none is available
      */
     public function getAuthenticationEntryPoint();
 
@@ -102,7 +102,7 @@ public function hasRequestPatterns();
     /**
      * Sets request patterns
      *
-     * @param array $requestPatterns Array of \Neos\Flow\Security\RequestPatternInterface to be set
+     * @param array<RequestPatternInterface> $requestPatterns Array of \Neos\Flow\Security\RequestPatternInterface to be set
      * @return void
      * @see hasRequestPattern()
      */
@@ -139,14 +139,14 @@ public function getCredentials();
     /**
      * Returns the account if one is authenticated, NULL otherwise.
      *
-     * @return Account An account object
+     * @return ?Account An account object
      */
     public function getAccount();
 
     /**
      * Set the (authenticated) account
      *
-     * @param Account $account An account object
+     * @param ?Account $account An account object
      * @return void
      */
     public function setAccount(?Account $account = null);
diff --git a/Neos.Flow/Classes/Security/Authorization/FilterFirewall.php b/Neos.Flow/Classes/Security/Authorization/FilterFirewall.php
index 1d2bc80d53..1798c1e927 100644
--- a/Neos.Flow/Classes/Security/Authorization/FilterFirewall.php
+++ b/Neos.Flow/Classes/Security/Authorization/FilterFirewall.php
@@ -72,7 +72,7 @@ public function __construct(
     /**
      * Injects the configuration settings
      *
-     * @param array $settings
+     * @param array<string,mixed> $settings
      * @return void
      */
     public function injectSettings(array $settings)
@@ -101,7 +101,7 @@ public function blockIllegalRequests(ActionRequest $request)
     }
 
     /**
-     * @param array $filterConfiguration
+     * @param array<string,mixed> $filterConfiguration
      * @return RequestFilter
      * @throws \Neos\Flow\Security\Exception\NoInterceptorFoundException
      * @throws \Neos\Flow\Security\Exception\NoRequestPatternFoundException
diff --git a/Neos.Flow/Classes/Security/Authorization/Interceptor/PolicyEnforcement.php b/Neos.Flow/Classes/Security/Authorization/Interceptor/PolicyEnforcement.php
index 72a2f0f84c..732c341b35 100644
--- a/Neos.Flow/Classes/Security/Authorization/Interceptor/PolicyEnforcement.php
+++ b/Neos.Flow/Classes/Security/Authorization/Interceptor/PolicyEnforcement.php
@@ -96,6 +96,7 @@ public function invoke()
 
         try {
             $this->authenticationManager->authenticate();
+            /** @phpstan-ignore catch.neverThrown (exception is not part of the api, can occur if the user was deleted) */
         } catch (EntityNotFoundException $exception) {
             throw new AuthenticationRequiredException('Could not authenticate. Looks like a broken session.', 1358971444, $exception);
         } catch (NoTokensAuthenticatedException $noTokensAuthenticatedException) {
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/ConjunctionGenerator.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/ConjunctionGenerator.php
index 6a4d46cdce..56bdbf7aa0 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/ConjunctionGenerator.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/ConjunctionGenerator.php
@@ -11,7 +11,7 @@
  * source code.
  */
 
-use Doctrine\Persistence\Mapping\ClassMetadata;
+use Doctrine\ORM\Mapping\ClassMetadata;
 use Doctrine\ORM\Query\Filter\SQLFilter as DoctrineSqlFilter;
 use Neos\Flow\Annotations as Flow;
 
@@ -35,14 +35,13 @@ public function __construct(array $expressions)
 
     /**
      * @param DoctrineSqlFilter $sqlFilter
-     * @param ClassMetadata $targetEntity Metadata object for the target entity to create the constraint for
+     * @param ClassMetadata<object> $targetEntity Metadata object for the target entity to create the constraint for
      * @param string $targetTableAlias The target table alias used in the current query
      * @return string
      */
     public function getSql(DoctrineSqlFilter $sqlFilter, ClassMetadata $targetEntity, $targetTableAlias)
     {
         $sql = '';
-        /** @var SqlGeneratorInterface $expression */
         foreach ($this->expressions as $expression) {
             $sql .= ($sql !== '' ? ' AND ' : '') . $expression->getSql($sqlFilter, $targetEntity, $targetTableAlias);
         }
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/DisjunctionGenerator.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/DisjunctionGenerator.php
index dafb1dfa59..c40043681e 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/DisjunctionGenerator.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/DisjunctionGenerator.php
@@ -11,7 +11,7 @@
  * source code.
  */
 
-use Doctrine\Persistence\Mapping\ClassMetadata;
+use Doctrine\ORM\Mapping\ClassMetadata;
 use Doctrine\ORM\Query\Filter\SQLFilter as DoctrineSqlFilter;
 use Neos\Flow\Annotations as Flow;
 
@@ -35,14 +35,13 @@ public function __construct(array $expressions)
 
     /**
      * @param DoctrineSqlFilter $sqlFilter
-     * @param ClassMetaData $targetEntity Metadata object for the target entity to create the constraint for
+     * @param ClassMetaData<object> $targetEntity Metadata object for the target entity to create the constraint for
      * @param string $targetTableAlias The target table alias used in the current query
      * @return string
      */
     public function getSql(DoctrineSqlFilter $sqlFilter, ClassMetadata $targetEntity, $targetTableAlias)
     {
         $sql = '';
-        /** @var SqlGeneratorInterface $expression */
         foreach ($this->expressions as $expression) {
             $sql .= ($sql !== '' ? ' OR ' : '') . $expression->getSql($sqlFilter, $targetEntity, $targetTableAlias);
         }
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilege.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilege.php
index 732aa8fade..5274aa6dd3 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilege.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilege.php
@@ -11,7 +11,6 @@
  * source code.
  */
 
-use Doctrine\Persistence\Mapping\ClassMetadata;
 use Doctrine\ORM\EntityManager;
 use Doctrine\ORM\EntityManagerInterface;
 use Neos\Eel\Context as EelContext;
@@ -60,11 +59,11 @@ public function matchesEntityType($entityType)
     /**
      * Note: The result of this method cannot be cached, as the target table alias might change for different query scenarios
      *
-     * @param ClassMetadata $targetEntity
+     * @param \Doctrine\ORM\Mapping\ClassMetadata<object> $targetEntity
      * @param string $targetTableAlias
      * @return string|null
      */
-    public function getSqlConstraint(ClassMetadata $targetEntity, $targetTableAlias)
+    public function getSqlConstraint(\Doctrine\ORM\Mapping\ClassMetadata $targetEntity, $targetTableAlias)
     {
         $this->evaluateMatcher();
 
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilegeExpressionParser.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilegeExpressionParser.php
index 4e9bf53e01..b97fafc83e 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilegeExpressionParser.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilegeExpressionParser.php
@@ -23,10 +23,10 @@
 class EntityPrivilegeExpressionParser extends CompilingEelParser
 {
     /**
-     * @param array $result
-     * @param array $sub
+     * @param array<string,mixed> $result
+     * @param array<string,mixed> $sub
      */
-    public function NotExpression_exp(&$result, $sub)
+    public function NotExpression_exp(&$result, $sub): void
     {
         if (!isset($result['code'])) {
             $result['code'] = '$context';
@@ -35,29 +35,29 @@ public function NotExpression_exp(&$result, $sub)
     }
 
     /**
-     * @param array $result
-     * @param array $sub
+     * @param array<string,mixed> $result
+     * @param array<string,mixed> $sub
      */
-    public function Disjunction_rgt(&$result, $sub)
+    public function Disjunction_rgt(&$result, $sub): void
     {
         $result['code'] = '$context->callAndWrap(\'disjunction\', array(' . $this->unwrapExpression($result['code']) . ', ' . $this->unwrapExpression($sub['code']) . '))';
     }
 
     /**
-     * @param array $result
-     * @param array $sub
+     * @param array<string,mixed> $result
+     * @param array<string,mixed> $sub
      */
-    public function Conjunction_rgt(&$result, $sub)
+    public function Conjunction_rgt(&$result, $sub): void
     {
         $result['code'] = '$context->callAndWrap(\'conjunction\', array(' . $this->unwrapExpression($result['code']) . ', ' . $this->unwrapExpression($sub['code']) . '))';
     }
 
     /**
-     * @param array $result
-     * @param array $sub
+     * @param array<string,mixed> $result
+     * @param array<string,mixed> $sub
      * @throws ParserException
      */
-    public function Comparison_rgt(&$result, $sub)
+    public function Comparison_rgt(&$result, $sub): void
     {
         $lval = $result['code'];
         $rval = $sub['code'];
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/FalseConditionGenerator.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/FalseConditionGenerator.php
index 6fa1e62d70..abd63bf8ff 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/FalseConditionGenerator.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/FalseConditionGenerator.php
@@ -24,7 +24,7 @@ class FalseConditionGenerator implements SqlGeneratorInterface
      * Returns an SQL query part that is basically a no-op in order to match no entity
      *
      * @param DoctrineSqlFilter $sqlFilter
-     * @param ClassMetadata $targetEntity
+     * @param ClassMetadata<object> $targetEntity
      * @param string $targetTableAlias
      * @return string
      */
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/NotExpressionGenerator.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/NotExpressionGenerator.php
index 5d52747678..5bbcc1921e 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/NotExpressionGenerator.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/NotExpressionGenerator.php
@@ -11,7 +11,7 @@
  * source code.
  */
 
-use Doctrine\Persistence\Mapping\ClassMetadata;
+use Doctrine\ORM\Mapping\ClassMetadata;
 use Doctrine\ORM\Query\Filter\SQLFilter as DoctrineSqlFilter;
 use Neos\Flow\Annotations as Flow;
 
@@ -35,7 +35,7 @@ public function __construct(SqlGeneratorInterface $expression)
 
     /**
      * @param DoctrineSqlFilter $sqlFilter
-     * @param ClassMetaData $targetEntity Metadata object for the target entity to create the constraint for
+     * @param ClassMetaData<object> $targetEntity Metadata object for the target entity to create the constraint for
      * @param string $targetTableAlias The target table alias used in the current query
      * @return string
      */
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/PropertyConditionGenerator.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/PropertyConditionGenerator.php
index 7df14fff9c..0f38d0225a 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/PropertyConditionGenerator.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/PropertyConditionGenerator.php
@@ -11,7 +11,7 @@
  * source code.
  */
 
-use Doctrine\ORM\Mapping\ClassMetadataInfo;
+use Doctrine\ORM\Mapping\ClassMetadata as ORMClassMetadata;
 use Doctrine\Persistence\Mapping\ClassMetadata;
 use Doctrine\ORM\EntityManagerInterface;
 use Doctrine\ORM\Mapping\QuoteStrategy;
@@ -45,7 +45,7 @@ class PropertyConditionGenerator implements SqlGeneratorInterface
     protected $operator;
 
     /**
-     * @var string|array
+     * @var string|array<string,string|object|null>
      */
     protected $operandDefinition;
 
@@ -58,7 +58,7 @@ class PropertyConditionGenerator implements SqlGeneratorInterface
      * Array of registered global objects that can be accessed as operands
      *
      * @Flow\InjectConfiguration("aop.globalObjects")
-     * @var array
+     * @var array<string,string>
      */
     protected $globalObjects = [];
 
@@ -95,7 +95,7 @@ class PropertyConditionGenerator implements SqlGeneratorInterface
     /**
      * Raw parameter values
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $parameters = [];
 
@@ -108,7 +108,7 @@ public function __construct($path)
     }
 
     /**
-     * @param string|array $operandDefinition
+     * @param string|array<string> $operandDefinition
      * @return PropertyConditionGenerator the current instance to allow for method chaining
      */
     public function equals($operandDefinition)
@@ -120,7 +120,7 @@ public function equals($operandDefinition)
     }
 
     /**
-     * @param string|array $operandDefinition
+     * @param string|array<string> $operandDefinition
      * @return PropertyConditionGenerator the current instance to allow for method chaining
      */
     public function notEquals($operandDefinition)
@@ -204,6 +204,9 @@ public function in($operandDefinition)
         if (is_array($this->operand) === false && ($this->operand instanceof \Traversable) === false) {
             throw new InvalidPolicyException(sprintf('The "in" operator needs an array as operand! Got: "%s"', $this->operand), 1416313526);
         }
+        if (!is_array($this->operandDefinition)) {
+            throw new \Exception('Cannot assign iterable operands to non-array operand definition', 1743959938);
+        }
         foreach ($this->operand as $iterator => $singleOperandValueDefinition) {
             $this->operandDefinition['inOperandValue' . $iterator] = $singleOperandValueDefinition;
         }
@@ -230,15 +233,16 @@ public function contains($operandDefinition): PropertyConditionGenerator
 
     /**
      * @param DoctrineSqlFilter $sqlFilter
-     * @param ClassMetadata $targetEntity
+     * @param ORMClassMetadata<object> $targetEntity
      * @param string $targetTableAlias
      * @return string
      * @throws InvalidQueryRewritingConstraintException
      * @throws \Exception
      */
-    public function getSql(DoctrineSqlFilter $sqlFilter, ClassMetadata $targetEntity, $targetTableAlias)
+    public function getSql(DoctrineSqlFilter $sqlFilter, ORMClassMetadata $targetEntity, $targetTableAlias)
     {
-        $targetEntityPropertyName = (strpos($this->path, '.') ? substr($this->path, 0, strpos($this->path, '.')) : $this->path);
+        $pivot = strpos($this->path, '.');
+        $targetEntityPropertyName = ($pivot ? substr($this->path, 0, $pivot) : $this->path);
         $quoteStrategy = $this->entityManager->getConfiguration()->getQuoteStrategy();
 
         if ($targetEntity->hasAssociation($targetEntityPropertyName) === false) {
@@ -248,7 +252,11 @@ public function getSql(DoctrineSqlFilter $sqlFilter, ClassMetadata $targetEntity
         } elseif ($targetEntity->isSingleValuedAssociation($targetEntityPropertyName) === true && $targetEntity->isAssociationInverseSide($targetEntityPropertyName) === false) {
             return $this->getSqlForManyToOneAndOneToOneRelationsWithPropertyPath($sqlFilter, $quoteStrategy, $targetEntity, $targetTableAlias, $targetEntityPropertyName);
         } elseif ($targetEntity->isSingleValuedAssociation($targetEntityPropertyName) === true && $targetEntity->isAssociationInverseSide($targetEntityPropertyName) === true) {
-            throw new InvalidQueryRewritingConstraintException('Single valued properties from the inverse side are not supported in a content security constraint path! Got: "' . $this->path . ' ' . $this->operator . ' ' . $this->operandDefinition . '"', 1416397754);
+            throw new InvalidQueryRewritingConstraintException(
+                'Single valued properties from the inverse side are not supported in a content security constraint path! Got: "'
+                    . $this->path . ' ' . $this->operator . ' ' . json_encode($this->operandDefinition) . '"',
+                1416397754
+            );
         } elseif ($targetEntity->isCollectionValuedAssociation($targetEntityPropertyName) === true) {
             return $this->getSqlForPropertyContains($sqlFilter, $quoteStrategy, $targetEntity, $targetTableAlias, $targetEntityPropertyName);
         }
@@ -259,17 +267,21 @@ public function getSql(DoctrineSqlFilter $sqlFilter, ClassMetadata $targetEntity
     /**
      * @param DoctrineSqlFilter $sqlFilter
      * @param QuoteStrategy $quoteStrategy
-     * @param ClassMetadataInfo $targetEntity
+     * @param ORMClassMetadata<object> $targetEntity
      * @param string $targetTableAlias
      * @param string $targetEntityPropertyName
      * @return string
      * @throws InvalidQueryRewritingConstraintException
      * @throws \Exception
      */
-    protected function getSqlForPropertyContains(DoctrineSqlFilter $sqlFilter, QuoteStrategy $quoteStrategy, ClassMetadata $targetEntity, string $targetTableAlias, string $targetEntityPropertyName): string
+    protected function getSqlForPropertyContains(DoctrineSqlFilter $sqlFilter, QuoteStrategy $quoteStrategy, ORMClassMetadata $targetEntity, string $targetTableAlias, string $targetEntityPropertyName): string
     {
         if ($this->operator !== 'contains') {
-            throw new InvalidQueryRewritingConstraintException('Multivalued properties are not supported in a content security constraint path unless the "contains" operation is used! Got: "' . $this->path . ' ' . $this->operator . ' ' . $this->operandDefinition . '"', 1416397655);
+            throw new InvalidQueryRewritingConstraintException(
+                'Multivalued properties are not supported in a content security constraint path unless the "contains" operation is used! Got: "'
+                    . $this->path . ' ' . $this->operator . ' ' . json_encode($this->operandDefinition) . '"',
+                1416397655
+            );
         }
 
         if (is_array($this->operandDefinition)) {
@@ -303,9 +315,6 @@ protected function getSqlForPropertyContains(DoctrineSqlFilter $sqlFilter, Quote
             $subQuerySql = 'SELECT ' . $reverseColumn . ' FROM ' . $associationMapping['joinTable']['name'] . ' WHERE ' . $joinColumn . ' = ' . $parameterValue;
         } else {
             $associationTargetClass = $targetEntity->getAssociationTargetClass($targetEntityPropertyName);
-            if ($associationTargetClass === null) {
-                throw new \InvalidArgumentException("Association name expected, '" . $targetEntityPropertyName . "' is not an association.", 1629871077);
-            }
             $subselectQuery = new Query($associationTargetClass);
             $rootAliases = $subselectQuery->getQueryBuilder()->getRootAliases();
             $primaryRootAlias = reset($rootAliases);
@@ -314,6 +323,9 @@ protected function getSqlForPropertyContains(DoctrineSqlFilter $sqlFilter, Quote
             $subselectQuery->getQueryBuilder()->select('IDENTITY(' . $primaryRootAlias . '.' . $associationMapping['mappedBy'] . ')');
             $subQuerySql = $subselectQuery->getSql();
         }
+        if (is_array($subQuerySql)) {
+            throw new \Exception('invalid sub query, must not be an array', 1743931303);
+        }
 
         return $targetTableAlias . '.' . $identityColumnName . ' IN (' . $subQuerySql . ')';
     }
@@ -321,14 +333,14 @@ protected function getSqlForPropertyContains(DoctrineSqlFilter $sqlFilter, Quote
     /**
      * @param DoctrineSqlFilter $sqlFilter
      * @param QuoteStrategy $quoteStrategy
-     * @param ClassMetadata $targetEntity
+     * @param ORMClassMetadata<object> $targetEntity
      * @param string $targetTableAlias
      * @param string $targetEntityPropertyName
      * @return string
      * @throws InvalidQueryRewritingConstraintException
      * @throws \Exception
      */
-    protected function getSqlForSimpleProperty(DoctrineSqlFilter $sqlFilter, QuoteStrategy $quoteStrategy, ClassMetadata $targetEntity, $targetTableAlias, $targetEntityPropertyName)
+    protected function getSqlForSimpleProperty(DoctrineSqlFilter $sqlFilter, QuoteStrategy $quoteStrategy, ORMClassMetadata $targetEntity, $targetTableAlias, $targetEntityPropertyName)
     {
         $quotedColumnName = $quoteStrategy->getColumnName($targetEntityPropertyName, $targetEntity, $this->entityManager->getConnection()->getDatabasePlatform());
         $propertyPointer = $targetTableAlias . '.' . $quotedColumnName;
@@ -346,35 +358,37 @@ protected function getSqlForSimpleProperty(DoctrineSqlFilter $sqlFilter, QuoteSt
     /**
      * @param DoctrineSqlFilter $sqlFilter
      * @param QuoteStrategy $quoteStrategy
-     * @param ClassMetadataInfo $targetEntity
+     * @param ORMClassMetadata<object> $targetEntity
      * @param string $targetTableAlias
      * @param string $targetEntityPropertyName
      * @return string
      * @throws InvalidQueryRewritingConstraintException
      * @throws \Exception
      */
-    protected function getSqlForManyToOneAndOneToOneRelationsWithoutPropertyPath(DoctrineSqlFilter $sqlFilter, QuoteStrategy $quoteStrategy, ClassMetadata $targetEntity, $targetTableAlias, $targetEntityPropertyName)
+    protected function getSqlForManyToOneAndOneToOneRelationsWithoutPropertyPath(DoctrineSqlFilter $sqlFilter, QuoteStrategy $quoteStrategy, ORMClassMetadata $targetEntity, $targetTableAlias, $targetEntityPropertyName)
     {
         $associationMapping = $targetEntity->getAssociationMapping($targetEntityPropertyName);
 
         $constraints = [];
-        foreach ($associationMapping['joinColumns'] as $joinColumn) {
+        foreach ($associationMapping['joinColumns'] ?? [] as $joinColumn) {
             $quotedColumnName = $quoteStrategy->getJoinColumnName($joinColumn, $targetEntity, $this->entityManager->getConnection()->getDatabasePlatform());
             $propertyPointer = $targetTableAlias . '.' . $quotedColumnName;
 
-            $operandAlias = $this->operandDefinition;
-            if (is_array($this->operandDefinition)) {
-                $operandAlias = key($this->operandDefinition);
-            }
+            $operandAlias = is_array($this->operandDefinition)
+                ? key($this->operandDefinition)
+                : $this->operandDefinition;
+
             $currentReferencedOperandName = $operandAlias . $joinColumn['referencedColumnName'];
             if (is_object($this->operand)) {
-                $operandMetadataInfo = $this->entityManager->getClassMetadata(TypeHandling::getTypeForValue($this->operand));
+                $type = TypeHandling::getTypeForValue($this->operand);
+                $operandMetadataInfo = $this->entityManager->getClassMetadata($type);
                 $currentReferencedValueOfOperand = $operandMetadataInfo->getFieldValue($this->operand, $operandMetadataInfo->getFieldForColumn($joinColumn['referencedColumnName']));
                 $this->setParameter($sqlFilter, $currentReferencedOperandName, $currentReferencedValueOfOperand, $associationMapping['type']);
             } elseif (is_array($this->operandDefinition)) {
                 foreach ($this->operandDefinition as $operandIterator => $singleOperandValue) {
                     if (is_object($singleOperandValue)) {
-                        $operandMetadataInfo = $this->entityManager->getClassMetadata(TypeHandling::getTypeForValue($singleOperandValue));
+                        $type = TypeHandling::getTypeForValue($singleOperandValue);
+                        $operandMetadataInfo = $this->entityManager->getClassMetadata($type);
                         $currentReferencedValueOfOperand = $operandMetadataInfo->getFieldValue($singleOperandValue, $operandMetadataInfo->getFieldForColumn($joinColumn['referencedColumnName']));
                         $this->setParameter($sqlFilter, $operandIterator, $currentReferencedValueOfOperand, $associationMapping['type']);
                     } elseif ($singleOperandValue === null) {
@@ -391,7 +405,7 @@ protected function getSqlForManyToOneAndOneToOneRelationsWithoutPropertyPath(Doc
     /**
      * @param DoctrineSqlFilter $sqlFilter
      * @param QuoteStrategy $quoteStrategy
-     * @param ClassMetadataInfo $targetEntity
+     * @param ORMClassMetadata<object> $targetEntity
      * @param string $targetTableAlias
      * @param string $targetEntityPropertyName
      * @return string
@@ -405,19 +419,22 @@ protected function getSqlForManyToOneAndOneToOneRelationsWithPropertyPath(Doctri
         $associationMapping = $targetEntity->getAssociationMapping($targetEntityPropertyName);
 
         $subselectConstraintQueries = [];
-        foreach ($associationMapping['joinColumns'] as $joinColumn) {
+        foreach ($associationMapping['joinColumns'] ?? [] as $joinColumn) {
             $rootAliases = $subselectQuery->getQueryBuilder()->getRootAliases();
             $subselectQuery->getQueryBuilder()->select($rootAliases[0] . '.' . $targetEntity->getFieldForColumn($joinColumn['referencedColumnName']));
             $subselectSql = $subselectQuery->getSql();
+            if (is_array($subselectSql)) {
+                $subselectSql = implode(' ', $subselectSql);
+            }
             foreach ($subselectQuery->getParameters() as $parameter) {
                 $parameterValue = $parameter->getValue();
                 if (is_object($parameterValue)) {
                     $parameterValue = $this->persistenceManager->getIdentifierByObject($parameter->getValue());
                 }
-                $subselectSql = preg_replace('/\?/', $this->entityManager->getConnection()->quote($parameterValue, $parameter->getType()), $subselectSql, 1);
+                $subselectSql = preg_replace('/\?/', $this->entityManager->getConnection()->quote($parameterValue, $parameter->getType()), $subselectSql ?: '', 1);
             }
             $quotedColumnName = $quoteStrategy->getJoinColumnName($joinColumn, $targetEntity, $this->entityManager->getConnection()->getDatabasePlatform());
-            $subselectIdentifier = 'subselect' . md5($subselectSql);
+            $subselectIdentifier = 'subselect' . md5($subselectSql ?: '');
             $subselectConstraintQueries[] = $targetTableAlias . '.' . $quotedColumnName . ' IN (SELECT ' . $subselectIdentifier . '.' . $joinColumn['referencedColumnName'] . '_0 FROM (' . $subselectSql . ') AS ' . $subselectIdentifier . ' ) ';
         }
 
@@ -425,7 +442,7 @@ protected function getSqlForManyToOneAndOneToOneRelationsWithPropertyPath(Doctri
     }
 
     /**
-     * @param ClassMetadata $targetEntity
+     * @param ClassMetadata<object> $targetEntity
      * @param string $targetEntityPropertyName
      * @return Query
      */
@@ -494,6 +511,9 @@ protected function getConstraintStringForSimpleProperty(DoctrineSqlFilter $sqlFi
                 }
                 $parameter = implode(',', $parameters);
             } elseif (!($this->getRawParameterValue($operandDefinition) === null || ($this->operator === 'in' && $this->getRawParameterValue($operandDefinition) === []))) {
+                if (!is_string($operandDefinition)) {
+                    throw new \Exception('SQL filter parameters must be of type string, ' . get_debug_type($operandDefinition) . ' given.', 1743929393);
+                }
                 $parameter = $sqlFilter->getParameter($operandDefinition);
             }
         } catch (\InvalidArgumentException $exception) {
@@ -567,11 +587,12 @@ public function getValueForOperand($expression)
      * @param DoctrineSqlFilter $sqlFilter
      * @param mixed $name
      * @param mixed $value
-     * @param string $type
+     * @param string|int|null $type
      * @return void
      */
     protected function setParameter(DoctrineSqlFilter $sqlFilter, $name, $value, $type = null)
     {
+        /** @phpstan-ignore argument.type (currently, doctrine also can handle integers) */
         $sqlFilter->setParameter($name, $value, $type);
         $this->parameters[$name] = $value;
     }
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/SqlFilter.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/SqlFilter.php
index e43d3f70d2..f1b3ba9d67 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/SqlFilter.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/SqlFilter.php
@@ -40,7 +40,7 @@ class SqlFilter extends DoctrineSqlFilter
     /**
      * Gets the SQL query part to add to a query.
      *
-     * @param ClassMetadata $targetEntity Metadata object for the target entity to be filtered
+     * @param ClassMetadata<object> $targetEntity Metadata object for the target entity to be filtered
      * @param string $targetTableAlias The target table alias used in the current query
      * @return string The constraint SQL if there is available, empty string otherwise
      */
@@ -107,6 +107,9 @@ public function addFilterConstraint(ClassMetadata $targetEntity, $targetTableAli
      */
     protected function initializeDependencies()
     {
+        if (!Bootstrap::$staticObjectManager) {
+            throw new \Exception('Cannot initialize dependencies without the static object manager', 1744398442);
+        }
         if ($this->securityContext === null) {
             $this->securityContext = Bootstrap::$staticObjectManager->get(Context::class);
         }
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/SqlGeneratorInterface.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/SqlGeneratorInterface.php
index 6f096aec14..c061488576 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/SqlGeneratorInterface.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/SqlGeneratorInterface.php
@@ -11,7 +11,7 @@
  * source code.
  */
 
-use Doctrine\Persistence\Mapping\ClassMetadata;
+use Doctrine\ORM\Mapping\ClassMetadata;
 use Doctrine\ORM\Query\Filter\SQLFilter as DoctrineSqlFilter;
 use Neos\Flow\Annotations as Flow;
 
@@ -22,7 +22,7 @@ interface SqlGeneratorInterface
 {
     /**
      * @param DoctrineSqlFilter $sqlFilter
-     * @param ClassMetadata $targetEntity Metadata object for the target entity to create the constraint for
+     * @param ClassMetadata<object> $targetEntity Metadata object for the target entity to create the constraint for
      * @param string $targetTableAlias The target table alias used in the current query
      * @return string
      */
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/TrueConditionGenerator.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/TrueConditionGenerator.php
index 71f5b97f95..68fd7e4e8a 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/TrueConditionGenerator.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/TrueConditionGenerator.php
@@ -24,7 +24,7 @@ class TrueConditionGenerator implements SqlGeneratorInterface
      * Returns an SQL query part that is basically a no-op in order to match any entity
      *
      * @param DoctrineSqlFilter $sqlFilter
-     * @param ClassMetadata $targetEntity
+     * @param ClassMetadata<object> $targetEntity
      * @param string $targetTableAlias
      * @return string
      */
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/EntityPrivilegeInterface.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/EntityPrivilegeInterface.php
index e9dab06ce2..096207a62b 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/EntityPrivilegeInterface.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Entity/EntityPrivilegeInterface.php
@@ -11,7 +11,7 @@
  * source code.
  */
 
-use Doctrine\Persistence\Mapping\ClassMetadata;
+use Doctrine\ORM\Mapping\ClassMetadata;
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\Security\Authorization\Privilege\PrivilegeInterface;
 
@@ -32,9 +32,9 @@ interface EntityPrivilegeInterface extends PrivilegeInterface
     public function matchesEntityType($entityType);
 
     /**
-     * @param ClassMetadata $targetEntity
+     * @param ClassMetadata<object> $targetEntity
      * @param string $targetTableAlias
-     * @return string
+     * @return string|null
      */
     public function getSqlConstraint(ClassMetadata $targetEntity, $targetTableAlias);
 }
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodPrivilege.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodPrivilege.php
index 8bed00aa93..aa8d2fb262 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodPrivilege.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodPrivilege.php
@@ -27,7 +27,7 @@
 class MethodPrivilege extends AbstractPrivilege implements MethodPrivilegeInterface
 {
     /**
-     * @var array
+     * @var array<string,array<string,array<string,mixed>>>
      */
     protected static $methodPermissions;
 
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodPrivilegePointcutFilter.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodPrivilegePointcutFilter.php
index b0887246b0..1b1766727c 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodPrivilegePointcutFilter.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodPrivilegePointcutFilter.php
@@ -34,7 +34,7 @@ class MethodPrivilegePointcutFilter implements PointcutFilterInterface
     protected $filters = null;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $methodPermissions = [];
 
@@ -83,9 +83,9 @@ public function initializeObject()
      * Checks if the specified class and method matches against the filter, i.e. if there is a policy entry to intercept this method.
      * This method also creates a cache entry for every method, to cache the associated roles and privileges.
      *
-     * @param string $className Name of the class to check the name of
+     * @param class-string $className Name of the class to check the name of
      * @param string $methodName Name of the method to check the name of
-     * @param string $methodDeclaringClassName Name of the class the method was originally declared in
+     * @param class-string $methodDeclaringClassName Name of the class the method was originally declared in
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
      * @return boolean true if the names match, otherwise false
      */
@@ -131,7 +131,7 @@ public function hasRuntimeEvaluationsDefinition(): bool
     /**
      * Returns runtime evaluations for the pointcut.
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition(): array
     {
@@ -158,9 +158,9 @@ public function reduceTargetClassNames(ClassNameIndex $classNameIndex): ClassNam
     }
 
     /**
-     * @param string $className
+     * @param class-string $className
      * @param string $methodName
-     * @param string $methodDeclaringClassName
+     * @param class-string $methodDeclaringClassName
      * @param mixed $pointcutQueryIdentifier
      * @return \Closure
      */
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodTargetExpressionParser.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodTargetExpressionParser.php
index dec1266201..b079bc44fc 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodTargetExpressionParser.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Method/MethodTargetExpressionParser.php
@@ -30,7 +30,7 @@ class MethodTargetExpressionParser extends PointcutExpressionParser
      * @param string $operator The operator
      * @param string $pointcutExpression The pointcut expression (value of the designator)
      * @param PointcutFilterComposite $pointcutFilterComposite An instance of the pointcut filter composite. The result (ie. the pointcut filter) will be added to this composite object.
-     * @param array &$trace
+     * @param array<mixed> &$trace
      * @return void
      * @throws InvalidPointcutExpressionException
      */
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Parameter/PrivilegeParameterInterface.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Parameter/PrivilegeParameterInterface.php
index 9403192c43..9cc8dfba11 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Parameter/PrivilegeParameterInterface.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Parameter/PrivilegeParameterInterface.php
@@ -41,7 +41,7 @@ public function getName();
     public function getValue();
 
     /**
-     * @return array|null
+     * @return array<mixed>|null
      */
     public function getPossibleValues();
 
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/Parameter/StringPrivilegeParameter.php b/Neos.Flow/Classes/Security/Authorization/Privilege/Parameter/StringPrivilegeParameter.php
index a099e429b2..1cc91f91d4 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/Parameter/StringPrivilegeParameter.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/Parameter/StringPrivilegeParameter.php
@@ -19,7 +19,7 @@
 class StringPrivilegeParameter extends AbstractPrivilegeParameter
 {
     /**
-     * @return array|null
+     * @return array<mixed>|null
      */
     public function getPossibleValues()
     {
diff --git a/Neos.Flow/Classes/Security/Authorization/Privilege/PrivilegeTarget.php b/Neos.Flow/Classes/Security/Authorization/Privilege/PrivilegeTarget.php
index d8b925bce1..42da213bc7 100644
--- a/Neos.Flow/Classes/Security/Authorization/Privilege/PrivilegeTarget.php
+++ b/Neos.Flow/Classes/Security/Authorization/Privilege/PrivilegeTarget.php
@@ -121,7 +121,7 @@ public function hasParameters(): bool
 
     /**
      * @param string $permission one of "GRANT", "DENY" or "ABSTAIN"
-     * @param array $parameters Optional key/value array with parameter names and -values
+     * @param array<string,mixed> $parameters Optional key/value array with parameter names and -values
      * @return PrivilegeInterface
      * @throws SecurityException
      */
@@ -151,7 +151,7 @@ public function getLabel(): string
     }
 
     /**
-     * @param array $parameters
+     * @param array<string,mixed> $parameters
      * @return \Closure
      */
     protected function createParameterMapper(array $parameters): \Closure
@@ -163,7 +163,7 @@ protected function createParameterMapper(array $parameters): \Closure
 
     /**
      * @param PrivilegeParameterDefinition $parameterDefinition
-     * @param array $parameters
+     * @param array<string,mixed> $parameters
      * @return PrivilegeParameterInterface
      * @throws SecurityException
      */
diff --git a/Neos.Flow/Classes/Security/Authorization/PrivilegeManager.php b/Neos.Flow/Classes/Security/Authorization/PrivilegeManager.php
index 6efd9bb355..1eb0a8a031 100644
--- a/Neos.Flow/Classes/Security/Authorization/PrivilegeManager.php
+++ b/Neos.Flow/Classes/Security/Authorization/PrivilegeManager.php
@@ -13,6 +13,7 @@
 
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\ObjectManagement\ObjectManagerInterface;
+use Neos\Flow\Security\Authorization\Privilege\Parameter\PrivilegeParameterInterface;
 use Neos\Flow\Security\Authorization\Privilege\PrivilegeInterface;
 use Neos\Flow\Security\Context;
 use Neos\Flow\Security\Policy\Role;
@@ -111,7 +112,7 @@ public function isGrantedForRoles(array $roles, $privilegeType, $subject, &$reas
      * Returns true if access is granted on the given privilege target in the current security context
      *
      * @param string $privilegeTargetIdentifier The identifier of the privilege target to decide on
-     * @param array $privilegeParameters Optional array of privilege parameters (simple key => value array)
+     * @param array<PrivilegeParameterInterface> $privilegeParameters Optional array of privilege parameters (simple key => value array)
      * @return boolean true if access is granted, false otherwise
      */
     public function isPrivilegeTargetGranted($privilegeTargetIdentifier, array $privilegeParameters = [])
@@ -124,7 +125,7 @@ public function isPrivilegeTargetGranted($privilegeTargetIdentifier, array $priv
      *
      * @param array<Role> $roles The roles that should be evaluated
      * @param string $privilegeTargetIdentifier The identifier of the privilege target to decide on
-     * @param array $privilegeParameters Optional array of privilege parameters (simple key => value array)
+     * @param array<PrivilegeParameterInterface> $privilegeParameters Optional array of privilege parameters (simple key => value array)
      * @return boolean true if access is granted, false otherwise
      */
     public function isPrivilegeTargetGrantedForRoles(array $roles, $privilegeTargetIdentifier, array $privilegeParameters = [])
@@ -134,7 +135,6 @@ public function isPrivilegeTargetGrantedForRoles(array $roles, $privilegeTargetI
         };
 
         $privileges = array_map($privilegeMapper, $roles);
-        /** @var PrivilegePermissionResult $result */
         $result = array_reduce($privileges, [$this, 'applyPrivilegeToResult'], new PrivilegePermissionResult());
 
         if ($result->getDenies() === 0 && $result->getGrants() > 0) {
diff --git a/Neos.Flow/Classes/Security/Authorization/PrivilegeManagerInterface.php b/Neos.Flow/Classes/Security/Authorization/PrivilegeManagerInterface.php
index da5b738c16..2f2ef9dde4 100644
--- a/Neos.Flow/Classes/Security/Authorization/PrivilegeManagerInterface.php
+++ b/Neos.Flow/Classes/Security/Authorization/PrivilegeManagerInterface.php
@@ -44,7 +44,7 @@ public function isGrantedForRoles(array $roles, $privilegeType, $subject, &$reas
      * Returns true if access is granted on the given privilege target in the current security context
      *
      * @param string $privilegeTargetIdentifier The identifier of the privilege target to decide on
-     * @param array $privilegeParameters Optional array of privilege parameters (simple key => value array)
+     * @param array<mixed> $privilegeParameters Optional array of privilege parameters (simple key => value array)
      * @return boolean true if access is granted, false otherwise
      */
     public function isPrivilegeTargetGranted($privilegeTargetIdentifier, array $privilegeParameters = []);
@@ -54,7 +54,7 @@ public function isPrivilegeTargetGranted($privilegeTargetIdentifier, array $priv
      *
      * @param array<Role> $roles The roles that should be evaluated
      * @param string $privilegeTargetIdentifier The identifier of the privilege target to decide on
-     * @param array $privilegeParameters Optional array of privilege parameters (simple key => value array)
+     * @param array<mixed> $privilegeParameters Optional array of privilege parameters (simple key => value array)
      * @return boolean true if access is granted, false otherwise
      */
     public function isPrivilegeTargetGrantedForRoles(array $roles, $privilegeTargetIdentifier, array $privilegeParameters = []);
diff --git a/Neos.Flow/Classes/Security/Authorization/PrivilegePermissionResult.php b/Neos.Flow/Classes/Security/Authorization/PrivilegePermissionResult.php
index 92eabf6397..5cb35aea57 100644
--- a/Neos.Flow/Classes/Security/Authorization/PrivilegePermissionResult.php
+++ b/Neos.Flow/Classes/Security/Authorization/PrivilegePermissionResult.php
@@ -25,7 +25,7 @@ class PrivilegePermissionResult
     protected $abstains = 0;
 
     /**
-     * @var array
+     * @var array<int,string>
      */
     protected $effectivePrivilegeIdentifiersWithPermission = [];
 
@@ -101,7 +101,7 @@ public function getAbstains(): int
     }
 
     /**
-     * @return array
+     * @return array<int,string>
      */
     public function getEffectivePrivilegeIdentifiersWithPermission(): array
     {
diff --git a/Neos.Flow/Classes/Security/Authorization/TestingPrivilegeManager.php b/Neos.Flow/Classes/Security/Authorization/TestingPrivilegeManager.php
index ef758473b7..696b1c6bb3 100644
--- a/Neos.Flow/Classes/Security/Authorization/TestingPrivilegeManager.php
+++ b/Neos.Flow/Classes/Security/Authorization/TestingPrivilegeManager.php
@@ -51,7 +51,7 @@ public function isGranted($privilegeType, $subject, &$reason = '')
      * or if set based on the override decision value.
      *
      * @param string $privilegeTargetIdentifier The identifier of the privilege target to decide on
-     * @param array $privilegeParameters Optional array of privilege parameters (simple key => value array)
+     * @param array<mixed> $privilegeParameters Optional array of privilege parameters (simple key => value array)
      * @return boolean true if access is granted, false otherwise
      */
     public function isPrivilegeTargetGranted($privilegeTargetIdentifier, array $privilegeParameters = [])
diff --git a/Neos.Flow/Classes/Security/Context.php b/Neos.Flow/Classes/Security/Context.php
index 8726a4265e..f136872125 100644
--- a/Neos.Flow/Classes/Security/Context.php
+++ b/Neos.Flow/Classes/Security/Context.php
@@ -95,7 +95,7 @@ class Context
     protected $csrfProtectionStrategy = self::CSRF_ONE_PER_SESSION;
 
     /**
-     * @var array
+     * @var array<int,string>
      */
     protected $tokenStatusLabels = [
         1 => 'no credentials given',
@@ -149,7 +149,7 @@ class Context
 
     /**
      * CSRF tokens that are valid during this request but will be gone after.
-     * @var array
+     * @var array<string,bool>
      */
     protected $csrfTokensRemovedAfterCurrentRequest = [];
 
@@ -193,7 +193,7 @@ class Context
      * Array of registered global objects that can be accessed as operands
      *
      * @Flow\InjectConfiguration("aop.globalObjects")
-     * @var array
+     * @var array<string,string>
      */
     protected $globalObjects = [];
 
@@ -253,7 +253,7 @@ public function setRequest(ActionRequest $request)
     /**
      * Injects the configuration settings
      *
-     * @param array $settings
+     * @param array<string,mixed> $settings
      * @return void
      * @throws Exception
      */
@@ -624,7 +624,7 @@ public function clearContext()
 
     /**
      * @param Account $account
-     * @return array
+     * @return array<string,Role>
      */
     protected function collectRolesAndParentRolesFromAccount(Account $account): array
     {
@@ -640,7 +640,7 @@ protected function collectRolesAndParentRolesFromAccount(Account $account): arra
 
     /**
      * @param Role $role
-     * @return array
+     * @return array<string,Role>
      */
     protected function collectParentRoles(Role $role): array
     {
@@ -692,6 +692,9 @@ protected function isTokenActive(TokenInterface $token)
             if (isset($requestPatternsByType[$patternType]) && $requestPatternsByType[$patternType] === true) {
                 continue;
             }
+            if (!$this->request) {
+                throw new \Exception('Cannot evaluate request pattern without a request', 1743927165);
+            }
             $requestPatternsByType[$patternType] = $requestPattern->matchRequest($this->request);
         }
         return !in_array(false, $requestPatternsByType, true);
@@ -704,7 +707,7 @@ protected function isTokenActive(TokenInterface $token)
      *
      * @param array<TokenInterface> $managerTokens Array of tokens provided by the authentication manager
      * @param array<TokenInterface> $sessionTokens Array of tokens restored from the session
-     * @return array Array of Authentication\TokenInterface objects
+     * @return array<string,TokenInterface> Array of Authentication\TokenInterface objects
      */
     protected function mergeTokens(array $managerTokens, array $sessionTokens)
     {
@@ -848,6 +851,7 @@ public function getContextHash()
         $this->withoutAuthorizationChecks(function () use (&$contextHashSoFar) {
             foreach ($this->globalObjects as $globalObjectsRegisteredClassName) {
                 if (is_subclass_of($globalObjectsRegisteredClassName, CacheAwareInterface::class)) {
+                    /** @var class-string<CacheAwareInterface> $globalObjectsRegisteredClassName */
                     $globalObject = $this->objectManager->get($globalObjectsRegisteredClassName);
                     $contextHashSoFar .= '<' . $globalObject->getCacheEntryIdentifier();
                 }
diff --git a/Neos.Flow/Classes/Security/Cryptography/Algorithms.php b/Neos.Flow/Classes/Security/Cryptography/Algorithms.php
index f0d1f0c969..20e2e90898 100644
--- a/Neos.Flow/Classes/Security/Cryptography/Algorithms.php
+++ b/Neos.Flow/Classes/Security/Cryptography/Algorithms.php
@@ -32,6 +32,15 @@ class Algorithms
      */
     public static function pbkdf2($password, $salt, $iterationCount, $derivedKeyLength, $algorithm = 'sha256')
     {
+        if (!$algorithm) {
+            throw new \Exception('Algorithm must not be falsy', 1743877215);
+        }
+        if ($iterationCount < 1) {
+            throw new \Exception('Iteration count too low, must be at least 1', 1743877176);
+        }
+        if ($derivedKeyLength < 0) {
+            throw new \Exception('Derived key length too low, must be at least 0', 1743877275);
+        }
         return hash_pbkdf2($algorithm, $password, $salt, $iterationCount, $derivedKeyLength, true);
     }
 }
diff --git a/Neos.Flow/Classes/Security/Cryptography/FileBasedSimpleKeyService.php b/Neos.Flow/Classes/Security/Cryptography/FileBasedSimpleKeyService.php
index a2897353bd..2c9f5876a0 100644
--- a/Neos.Flow/Classes/Security/Cryptography/FileBasedSimpleKeyService.php
+++ b/Neos.Flow/Classes/Security/Cryptography/FileBasedSimpleKeyService.php
@@ -45,7 +45,7 @@ class FileBasedSimpleKeyService
     protected $hashService;
 
     /**
-     * @param array $settings
+     * @param array<string,mixed> $settings
      * @return void
      */
     public function injectSettings(array $settings)
@@ -116,7 +116,7 @@ public function keyExists($name)
      * Returns a key by its name
      *
      * @param string $name
-     * @return boolean
+     * @return string
      * @throws SecurityException
      */
     public function getKey($name)
diff --git a/Neos.Flow/Classes/Security/Cryptography/HashService.php b/Neos.Flow/Classes/Security/Cryptography/HashService.php
index 24df1e3af7..59f567d405 100644
--- a/Neos.Flow/Classes/Security/Cryptography/HashService.php
+++ b/Neos.Flow/Classes/Security/Cryptography/HashService.php
@@ -28,17 +28,17 @@ class HashService
 {
     /**
      * A private, unique key used for encryption tasks
-     * @var string
+     * @var string|false|null
      */
     protected $encryptionKey = null;
 
     /**
-     * @var array
+     * @var array<string,PasswordHashingStrategyInterface>
      */
     protected $passwordHashingStrategies = [];
 
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $strategySettings;
 
@@ -57,7 +57,7 @@ class HashService
     /**
      * Injects the settings of the package this controller belongs to.
      *
-     * @param array $settings Settings container of the current package
+     * @param array<string,mixed> $settings Settings container of the current package
      * @return void
      */
     public function injectSettings(array $settings)
@@ -72,12 +72,8 @@ public function injectSettings(array $settings)
      * @return string The hash of the string
      * @throws InvalidArgumentForHashGenerationException if something else than a string was given as parameter
      */
-    public function generateHmac($string)
+    public function generateHmac(string $string): string
     {
-        if (!is_string($string)) {
-            throw new InvalidArgumentForHashGenerationException('A hash can only be generated for a string, but "' . gettype($string) . '" was given.', 1255069587);
-        }
-
         return hash_hmac('sha1', $string, $this->getEncryptionKey());
     }
 
@@ -121,11 +117,8 @@ public function validateHmac($string, $hmac)
      * @throws InvalidHashException if the hash did not fit to the data.
      * @todo Mark as API once it is more stable
      */
-    public function validateAndStripHmac($string)
+    public function validateAndStripHmac(string $string): string
     {
-        if (!is_string($string)) {
-            throw new InvalidArgumentForHashGenerationException('A hash can only be validated for a string, but "' . gettype($string) . '" was given.', 1320829762);
-        }
         if (strlen($string) < 40) {
             throw new InvalidArgumentForHashGenerationException('A hashed string must contain at least 40 characters, the given string was only ' . strlen($string) . ' characters long.', 1320830276);
         }
@@ -188,12 +181,19 @@ protected function getPasswordHashingStrategyAndIdentifier($strategyIdentifier =
             }
             $strategyIdentifier = $this->strategySettings['default'];
         }
+        if (!is_string($strategyIdentifier)) {
+            throw new \Exception('Invalid strategy identifier', 1743877483);
+        }
 
         if (!isset($this->strategySettings[$strategyIdentifier])) {
             throw new MissingConfigurationException('No hashing strategy with identifier "' . $strategyIdentifier . '" configured', 1320758776);
         }
         $strategyObjectName = $this->strategySettings[$strategyIdentifier];
-        $this->passwordHashingStrategies[$strategyIdentifier] = $this->objectManager->get($strategyObjectName);
+        $strategy = $this->objectManager->get($strategyObjectName);
+        if (!$strategy instanceof PasswordHashingStrategyInterface) {
+            throw new \Exception('Invalid password hashing strategy', 1743877416);
+        }
+        $this->passwordHashingStrategies[$strategyIdentifier] = $strategy;
         return [$this->passwordHashingStrategies[$strategyIdentifier], $strategyIdentifier];
     }
 
diff --git a/Neos.Flow/Classes/Security/Cryptography/Pbkdf2HashingStrategy.php b/Neos.Flow/Classes/Security/Cryptography/Pbkdf2HashingStrategy.php
index e75a985c66..940f61c21c 100644
--- a/Neos.Flow/Classes/Security/Cryptography/Pbkdf2HashingStrategy.php
+++ b/Neos.Flow/Classes/Security/Cryptography/Pbkdf2HashingStrategy.php
@@ -68,6 +68,15 @@ public function __construct(int $dynamicSaltLength, int $iterationCount, int $de
     public function hashPassword($password, $staticSalt = null)
     {
         $dynamicSalt = UtilityAlgorithms::generateRandomBytes($this->dynamicSaltLength);
+        if (!$this->algorithm) {
+            throw new \Exception('Algorithm must not be falsy', 1743877215);
+        }
+        if ($this->iterationCount < 1) {
+            throw new \Exception('Iteration count too low, must be at least 1', 1743877176);
+        }
+        if ($this->derivedKeyLength < 0) {
+            throw new \Exception('Derived key length too low, must be at least 0', 1743877275);
+        }
         $result = hash_pbkdf2($this->algorithm, $password, $dynamicSalt . $staticSalt, $this->iterationCount, $this->derivedKeyLength, true);
         return base64_encode($dynamicSalt) . ',' . base64_encode($result);
     }
@@ -88,6 +97,12 @@ public function validatePassword($password, $hashedPasswordAndSalt, $staticSalt
         if (count($parts) !== 2) {
             throw new \InvalidArgumentException('The derived key with salt must contain a salt, separated with a comma from the derived key', 1306172911);
         }
+        if (!$this->algorithm) {
+            throw new \Exception('Algorithm must not be falsy', 1743877215);
+        }
+        if ($this->iterationCount < 1) {
+            throw new \Exception('Iteration count too low, must be at least 1', 1743877176);
+        }
         $dynamicSalt = base64_decode($parts[0]);
         $derivedKey = base64_decode($parts[1]);
         $derivedKeyLength = strlen($derivedKey);
diff --git a/Neos.Flow/Classes/Security/Cryptography/RsaWalletServiceInterface.php b/Neos.Flow/Classes/Security/Cryptography/RsaWalletServiceInterface.php
index 8803d39061..c839393a1e 100644
--- a/Neos.Flow/Classes/Security/Cryptography/RsaWalletServiceInterface.php
+++ b/Neos.Flow/Classes/Security/Cryptography/RsaWalletServiceInterface.php
@@ -54,7 +54,7 @@ public function registerPublicKeyFromString($publicKeyString);
      * @return OpenSslRsaKey The public key
      * @throws InvalidKeyPairIdException If the given fingerprint identifies no valid key pair
      */
-    public function getPublicKey($fingerprint);
+    public function getPublicKey(string $fingerprint): OpenSslRsaKey;
 
     /**
      * Decrypts the given cypher with the private key identified by the given fingerprint
@@ -67,7 +67,7 @@ public function getPublicKey($fingerprint);
      * @throws InvalidKeyPairIdException If the given fingerprint identifies no valid keypair
      * @throws DecryptionNotAllowedException If the given fingerprint identifies a keypair for encrypted passwords
      */
-    public function decrypt($cypher, $fingerprint);
+    public function decrypt(string $cypher, string $fingerprint): string;
 
     /**
      * Signs the given plaintext with the private key identified by the given fingerprint
@@ -77,7 +77,7 @@ public function decrypt($cypher, $fingerprint);
      * @return string The signature of the given plaintext
      * @throws InvalidKeyPairIdException If the given fingerprint identifies no valid keypair
      */
-    public function sign($plaintext, $fingerprint);
+    public function sign(string $plaintext, string $fingerprint): string;
 
     /**
      * Checks whether the given signature is valid for the given plaintext
@@ -88,7 +88,7 @@ public function sign($plaintext, $fingerprint);
      * @param string $fingerprint The fingerprint to identify to correct public key
      * @return boolean true if the signature is correct for the given plaintext and public key
      */
-    public function verifySignature($plaintext, $signature, $fingerprint);
+    public function verifySignature(string $plaintext, string $signature, string $fingerprint): bool;
 
     /**
      * Encrypts the given plaintext with the public key identified by the given fingerprint
@@ -109,14 +109,12 @@ public function encryptWithPublicKey($plaintext, $fingerprint);
      * @param string $fingerprint The fingerprint to identify to correct private key
      * @return boolean true if the password is correct
      */
-    public function checkRSAEncryptedPassword($encryptedPassword, $passwordHash, $salt, $fingerprint);
+    public function checkRSAEncryptedPassword(string $encryptedPassword, string $passwordHash, string $salt, string $fingerprint): bool;
 
     /**
      * Destroys the keypair identified by the given fingerprint
      *
-     * @param string $fingerprint The fingerprint
-     * @return void
      * @throws InvalidKeyPairIdException If the given fingerprint identifies no valid key pair
      */
-    public function destroyKeypair($fingerprint);
+    public function destroyKeypair(string $fingerprint): void;
 }
diff --git a/Neos.Flow/Classes/Security/Cryptography/RsaWalletServicePhp.php b/Neos.Flow/Classes/Security/Cryptography/RsaWalletServicePhp.php
index e861eb01ea..e302021639 100644
--- a/Neos.Flow/Classes/Security/Cryptography/RsaWalletServicePhp.php
+++ b/Neos.Flow/Classes/Security/Cryptography/RsaWalletServicePhp.php
@@ -31,13 +31,13 @@ class RsaWalletServicePhp implements RsaWalletServiceInterface
     protected $keystorePathAndFilename;
 
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $keys = [];
 
     /**
      * The openSSL configuration
-     * @var array
+     * @var array<mixed>
      */
     protected $openSSLConfiguration = [];
 
@@ -55,7 +55,7 @@ class RsaWalletServicePhp implements RsaWalletServiceInterface
     /**
      * Injects the OpenSSL configuration to be used
      *
-     * @param array $settings
+     * @param array<string,mixed> $settings
      * @return void
      * @throws MissingConfigurationException
      * @throws SecurityException
@@ -88,7 +88,7 @@ public function injectSettings(array $settings)
     public function initializeObject()
     {
         if (file_exists($this->keystorePathAndFilename)) {
-            $this->keys = unserialize(file_get_contents($this->keystorePathAndFilename), ['allowed_classes' => [OpenSslRsaKey::class]]);
+            $this->keys = unserialize(file_get_contents($this->keystorePathAndFilename) ?: '', ['allowed_classes' => [OpenSslRsaKey::class]]);
         }
         $this->saveKeysOnShutdown = false;
     }
@@ -128,6 +128,9 @@ public function generateNewKeypair($usedForPasswords = false)
     public function registerKeyPairFromPrivateKeyString($privateKeyString, $usedForPasswords = false)
     {
         $keyResource = openssl_pkey_get_private($privateKeyString);
+        if ($keyResource === false) {
+            throw new \Exception('Failed to load private key', 1743877014);
+        }
 
         $modulus = $this->getModulus($keyResource);
         $publicKeyString = $this->getPublicKeyString($keyResource);
@@ -149,6 +152,9 @@ public function registerKeyPairFromPrivateKeyString($privateKeyString, $usedForP
     public function registerPublicKeyFromString($publicKeyString)
     {
         $keyResource = openssl_pkey_get_public($publicKeyString);
+        if ($keyResource === false) {
+            throw new \Exception('Failed to load public key', 1743876948);
+        }
 
         $modulus = $this->getModulus($keyResource);
         $publicKey = new OpenSslRsaKey($modulus, $publicKeyString);
@@ -163,9 +169,9 @@ public function registerPublicKeyFromString($publicKeyString)
      * @return OpenSslRsaKey The public key
      * @throws InvalidKeyPairIdException If the given fingerprint identifies no valid key pair
      */
-    public function getPublicKey($fingerprint)
+    public function getPublicKey(string $fingerprint): OpenSslRsaKey
     {
-        if ($fingerprint === null || !isset($this->keys[$fingerprint])) {
+        if (!isset($this->keys[$fingerprint])) {
             throw new InvalidKeyPairIdException('Invalid keypair fingerprint given', 1231438860);
         }
 
@@ -199,16 +205,16 @@ public function encryptWithPublicKey($plaintext, $fingerprint)
      * Note: You should never decrypt a password with this function. Use checkRSAEncryptedPassword()
      * to check passwords!
      *
-     * @param string $cipher cipher text to decrypt
+     * @param string $cypher cipher text to decrypt
      * @param string $fingerprint The fingerprint to identify the private key (RSA public key fingerprint)
      * @return string The decrypted text
      * @throws InvalidKeyPairIdException If the given fingerprint identifies no valid keypair
      * @throws DecryptionNotAllowedException If the given fingerprint identifies a keypair for encrypted passwords
      * @throws SecurityException If decryption failed for some other reason
      */
-    public function decrypt($cipher, $fingerprint)
+    public function decrypt(string $cypher, string $fingerprint): string
     {
-        if ($fingerprint === null || !isset($this->keys[$fingerprint])) {
+        if (!isset($this->keys[$fingerprint])) {
             throw new InvalidKeyPairIdException('Invalid keypair fingerprint given', 1231438861);
         }
 
@@ -218,7 +224,7 @@ public function decrypt($cipher, $fingerprint)
             throw new DecryptionNotAllowedException('You are not allowed to decrypt passwords!', 1233655350);
         }
 
-        return $this->decryptWithPrivateKey($cipher, $keyPair['privateKey']);
+        return $this->decryptWithPrivateKey($cypher, $keyPair['privateKey']);
     }
 
     /**
@@ -229,9 +235,9 @@ public function decrypt($cipher, $fingerprint)
      * @return string The signature of the given plaintext
      * @throws InvalidKeyPairIdException If the given fingerprint identifies no valid keypair
      */
-    public function sign($plaintext, $fingerprint)
+    public function sign(string $plaintext, string $fingerprint): string
     {
-        if ($fingerprint === null || !isset($this->keys[$fingerprint])) {
+        if (!isset($this->keys[$fingerprint])) {
             throw new InvalidKeyPairIdException('Invalid keypair fingerprint given', 1299095799);
         }
 
@@ -251,9 +257,9 @@ public function sign($plaintext, $fingerprint)
      * @return boolean true if the signature is correct for the given plaintext and public key
      * @throws InvalidKeyPairIdException
      */
-    public function verifySignature($plaintext, $signature, $fingerprint)
+    public function verifySignature(string $plaintext, string $signature, string $fingerprint): bool
     {
-        if ($fingerprint === null || !isset($this->keys[$fingerprint])) {
+        if (!isset($this->keys[$fingerprint])) {
             throw new InvalidKeyPairIdException('Invalid keypair fingerprint given', 1304959763);
         }
 
@@ -273,9 +279,9 @@ public function verifySignature($plaintext, $signature, $fingerprint)
      * @return boolean true if the password is correct
      * @throws InvalidKeyPairIdException If the given fingerprint identifies no valid keypair
      */
-    public function checkRSAEncryptedPassword($encryptedPassword, $passwordHash, $salt, $fingerprint)
+    public function checkRSAEncryptedPassword(string $encryptedPassword, string $passwordHash, string $salt, string $fingerprint): bool
     {
-        if ($fingerprint === null || !isset($this->keys[$fingerprint])) {
+        if (!isset($this->keys[$fingerprint])) {
             throw new InvalidKeyPairIdException('Invalid keypair fingerprint given', 1233655216);
         }
 
@@ -288,12 +294,11 @@ public function checkRSAEncryptedPassword($encryptedPassword, $passwordHash, $sa
      * Destroys the keypair identified by the given fingerprint
      *
      * @param string $fingerprint The fingerprint
-     * @return void
      * @throws InvalidKeyPairIdException If the given fingerprint identifies no valid key pair
      */
-    public function destroyKeypair($fingerprint)
+    public function destroyKeypair(string $fingerprint): void
     {
-        if ($fingerprint === null || !isset($this->keys[$fingerprint])) {
+        if (!isset($this->keys[$fingerprint])) {
             throw new InvalidKeyPairIdException('Invalid keypair fingerprint given', 1231438863);
         }
 
@@ -322,6 +327,9 @@ private function getPrivateKeyString(\OpenSSLAsymmetricKey $keyResource)
     private function getPublicKeyString(\OpenSSLAsymmetricKey $keyResource)
     {
         $keyDetails = openssl_pkey_get_details($keyResource);
+        if ($keyDetails === false) {
+            throw new \Exception('Failed to get public key details', 1743876036);
+        }
 
         return $keyDetails['key'];
     }
@@ -335,6 +343,9 @@ private function getPublicKeyString(\OpenSSLAsymmetricKey $keyResource)
     private function getModulus(\OpenSSLAsymmetricKey $keyResource)
     {
         $keyDetails = openssl_pkey_get_details($keyResource);
+        if ($keyDetails === false) {
+            throw new \Exception('Failed to load public key details', 1743875916);
+        }
         return strtoupper(bin2hex($keyDetails['rsa']['n']));
     }
 
@@ -350,6 +361,9 @@ private function decryptWithPrivateKey($cipher, OpenSslRsaKey $privateKey)
     {
         $decrypted = '';
         $key = openssl_pkey_get_private($privateKey->getKeyString());
+        if ($key === false) {
+            throw new \Exception('Failed to load private key', 1743875855);
+        }
         if (openssl_private_decrypt($cipher, $decrypted, $key, $this->paddingAlgorithm) === false) {
             // Fallback for data that was encrypted with old default OPENSSL_PKCS1_PADDING
             if ($this->paddingAlgorithm !== OPENSSL_PKCS1_PADDING) {
@@ -374,7 +388,7 @@ private function decryptWithPrivateKey($cipher, OpenSslRsaKey $privateKey)
      * consistent key access.
      *
      * @param OpenSslRsaKey $publicKey The public key
-     * @param OpenSslRsaKey $privateKey The private key
+     * @param OpenSslRsaKey|null $privateKey The private key
      * @param boolean $usedForPasswords true if this keypair should be used to encrypt passwords (then decryption won't be allowed!).
      * @return string The fingerprint which is used as an identifier for storing the key pair
      */
@@ -439,7 +453,13 @@ public function shutdownObject()
     public function getFingerprintByPublicKey($publicKeyString)
     {
         $keyResource = openssl_pkey_get_public($publicKeyString);
+        if ($keyResource === false) {
+            throw new \Exception('Could not extract public key', 1743875618);
+        }
         $keyDetails = openssl_pkey_get_details($keyResource);
+        if ($keyDetails === false) {
+            throw new \Exception('Could not extract public key details', 1743875650);
+        }
         $modulus = $this->sshConvertMpint($keyDetails['rsa']['n']);
         $publicExponent = $this->sshConvertMpint($keyDetails['rsa']['e']);
 
diff --git a/Neos.Flow/Classes/Security/DummyContext.php b/Neos.Flow/Classes/Security/DummyContext.php
index a9689677ef..57474421d9 100644
--- a/Neos.Flow/Classes/Security/DummyContext.php
+++ b/Neos.Flow/Classes/Security/DummyContext.php
@@ -35,7 +35,7 @@ class DummyContext extends Context
 
     /**
      * Array of configured tokens (might have request patterns)
-     * @var array
+     * @var array<TokenInterface>
      */
     protected $tokens = [];
 
@@ -86,7 +86,7 @@ public function getAuthenticationStrategy()
      * Sets the Authentication\Tokens of the security context which should be active.
      *
      * @param TokenInterface[] $tokens Array of set tokens
-     * @return array
+     * @return array<TokenInterface>
      */
     public function setAuthenticationTokens(array $tokens)
     {
@@ -110,7 +110,7 @@ public function getAuthenticationTokens()
      * active for the current request and of the given type. If a token has a request pattern that cannot match
      * against the current request it is determined as not active.
      *
-     * @param string $className The class name
+     * @param class-string<TokenInterface> $className The class name
      * @return TokenInterface[] Array of set tokens of the specified type
      */
     public function getAuthenticationTokensOfType($className)
@@ -132,7 +132,7 @@ public function getAuthenticationTokensOfType($className)
      *
      * The "Neos.Flow:Everybody" roles is always returned.
      *
-     * @return Role[]
+     * @return Role[]|null
      */
     public function getRoles()
     {
@@ -185,7 +185,7 @@ public function setCsrfProtectionToken($csrfProtectionToken)
      * Returns the current CSRF protection token. A new one is created when needed, depending on the  configured CSRF
      * protection strategy.
      *
-     * @return string
+     * @return string|null
      */
     public function getCsrfProtectionToken()
     {
@@ -231,7 +231,7 @@ public function setInterceptedRequest(?ActionRequest $interceptedRequest = null)
      * Returns the request, that has been stored for later resuming after it
      * has been intercepted by a security exception, NULL if there is none.
      *
-     * @return ActionRequest
+     * @return ActionRequest|null
      */
     public function getInterceptedRequest()
     {
diff --git a/Neos.Flow/Classes/Security/Policy/PolicyService.php b/Neos.Flow/Classes/Security/Policy/PolicyService.php
index f2e8228ccb..aab68aa904 100644
--- a/Neos.Flow/Classes/Security/Policy/PolicyService.php
+++ b/Neos.Flow/Classes/Security/Policy/PolicyService.php
@@ -46,7 +46,7 @@ class PolicyService
     protected $configurationManager;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $policyConfiguration;
 
@@ -198,7 +198,7 @@ protected function initializePrivilegeTargets(): void
                     if ($parameterClassName === null) {
                         throw new SecurityException(sprintf('No "className" defined for parameter "%s" in privilegeTarget "%s"', $parameterName, $privilegeTargetIdentifier), 1396021782);
                     }
-                    if (!in_array(PrivilegeParameterInterface::class, class_implements($parameterClassName), true)) {
+                    if (!in_array(PrivilegeParameterInterface::class, class_implements($parameterClassName) ?: [], true)) {
                         throw new SecurityException(sprintf('PrivilegeParameterInterface must be implemented for "className" defined for parameter "%s" in privilegeTarget "%s"', $parameterName, $privilegeTargetIdentifier), 1396021782);
                     }
                     $parameterDefinitions[$parameterName] = new PrivilegeParameterDefinition($parameterName, $parameterClassName);
@@ -266,7 +266,7 @@ public function getRoles($includeAbstract = false): array
      * Returns all privileges of the given type
      *
      * @param string $type Full qualified class or interface name
-     * @return array
+     * @return array<PrivilegeInterface>
      * @throws InvalidConfigurationTypeException
      * @throws SecurityException
      */
@@ -325,7 +325,7 @@ public function reset(): void
      * This signal can be used to add roles and/or privilegeTargets during runtime. In the slot make sure to receive the
      * $policyConfiguration array by reference so you can alter it.
      *
-     * @param array $policyConfiguration The policy configuration
+     * @param array<mixed> $policyConfiguration The policy configuration
      * @return void
      * @Flow\Signal
      */
diff --git a/Neos.Flow/Classes/Security/Policy/Role.php b/Neos.Flow/Classes/Security/Policy/Role.php
index e4ae2790ac..b1e5968140 100644
--- a/Neos.Flow/Classes/Security/Policy/Role.php
+++ b/Neos.Flow/Classes/Security/Policy/Role.php
@@ -14,6 +14,7 @@
  */
 
 use Neos\Flow\Annotations as Flow;
+use Neos\Flow\Security\Authorization\Privilege\Parameter\PrivilegeParameterInterface;
 use Neos\Flow\Security\Authorization\Privilege\PrivilegeInterface;
 
 /**
@@ -246,7 +247,7 @@ public function getPrivilegesByType(string $className): array
 
     /**
      * @param string $privilegeTargetIdentifier
-     * @param array $privilegeParameters
+     * @param array<PrivilegeParameterInterface> $privilegeParameters
      * @return PrivilegeInterface|null the matching privilege or NULL if no privilege exists for the given constraints
      */
     public function getPrivilegeForTarget(string $privilegeTargetIdentifier, array $privilegeParameters = []): ?PrivilegeInterface
diff --git a/Neos.Flow/Classes/Security/Policy/RoleConverter.php b/Neos.Flow/Classes/Security/Policy/RoleConverter.php
index bd599cb85d..b90c842404 100644
--- a/Neos.Flow/Classes/Security/Policy/RoleConverter.php
+++ b/Neos.Flow/Classes/Security/Policy/RoleConverter.php
@@ -52,7 +52,7 @@ class RoleConverter extends AbstractTypeConverter
      *
      * @param mixed $source
      * @param string $targetType
-     * @param array $convertedChildProperties
+     * @param array<mixed> $convertedChildProperties
      * @param PropertyMappingConfigurationInterface|null $configuration
      * @return object the target type
      */
diff --git a/Neos.Flow/Classes/Security/RequestPattern/ControllerObjectName.php b/Neos.Flow/Classes/Security/RequestPattern/ControllerObjectName.php
index b95619530c..9c61769698 100644
--- a/Neos.Flow/Classes/Security/RequestPattern/ControllerObjectName.php
+++ b/Neos.Flow/Classes/Security/RequestPattern/ControllerObjectName.php
@@ -21,14 +21,14 @@
 class ControllerObjectName implements RequestPatternInterface
 {
     /**
-     * @var array
+     * @var array<string,string>
      */
     protected $options;
 
     /**
      * Expects options in the form array('controllerObjectNamePattern' => '<regularExpression>')
      *
-     * @param array $options
+     * @param array<string,string> $options
      */
     public function __construct(array $options)
     {
diff --git a/Neos.Flow/Classes/Security/RequestPattern/CsrfProtection.php b/Neos.Flow/Classes/Security/RequestPattern/CsrfProtection.php
index ffa2eef7e2..f7a7bc8922 100644
--- a/Neos.Flow/Classes/Security/RequestPattern/CsrfProtection.php
+++ b/Neos.Flow/Classes/Security/RequestPattern/CsrfProtection.php
@@ -101,6 +101,9 @@ public function matchRequest(ActionRequest $request)
         }
 
         $controllerClassName = $this->objectManager->getClassNameByObjectName($request->getControllerObjectName());
+        if ($controllerClassName === false) {
+            throw new \Exception('Failed to resolve controller class name for ' . $request->getControllerObjectName(), 1743926779);
+        }
         $actionMethodName = $request->getControllerActionName() . 'Action';
 
         if (!$this->hasPolicyEntryForMethod($controllerClassName, $actionMethodName)) {
diff --git a/Neos.Flow/Classes/Security/RequestPattern/Host.php b/Neos.Flow/Classes/Security/RequestPattern/Host.php
index 1b1c1a00a9..3265905e68 100644
--- a/Neos.Flow/Classes/Security/RequestPattern/Host.php
+++ b/Neos.Flow/Classes/Security/RequestPattern/Host.php
@@ -25,14 +25,14 @@
 class Host implements RequestPatternInterface
 {
     /**
-     * @var array
+     * @var array<string,string>
      */
     protected $options;
 
     /**
      * Expects options in the form array('hostPattern' => '<host pattern>')
      *
-     * @param array $options
+     * @param array<string,string> $options
      */
     public function __construct(array $options)
     {
diff --git a/Neos.Flow/Classes/Security/RequestPattern/Ip.php b/Neos.Flow/Classes/Security/RequestPattern/Ip.php
index 18cf903ad5..02358ebf46 100644
--- a/Neos.Flow/Classes/Security/RequestPattern/Ip.php
+++ b/Neos.Flow/Classes/Security/RequestPattern/Ip.php
@@ -35,14 +35,14 @@
 class Ip implements RequestPatternInterface
 {
     /**
-     * @var array
+     * @var array<string,string>
      */
     protected $options;
 
     /**
      * Expects options in the form array('cidrPattern' => '<CIDR IP Pattern>')
      *
-     * @param array $options
+     * @param array<string,string> $options
      */
     public function __construct(array $options)
     {
diff --git a/Neos.Flow/Classes/Security/RequestPattern/Uri.php b/Neos.Flow/Classes/Security/RequestPattern/Uri.php
index 9127691d1b..0121585cf1 100644
--- a/Neos.Flow/Classes/Security/RequestPattern/Uri.php
+++ b/Neos.Flow/Classes/Security/RequestPattern/Uri.php
@@ -21,14 +21,14 @@
 class Uri implements RequestPatternInterface
 {
     /**
-     * @var array
+     * @var array<string,string>
      */
     protected $options;
 
     /**
      * Expects options in the form array('uriPattern' => '<URI pattern>')
      *
-     * @param array $options
+     * @param array<string,string> $options
      */
     public function __construct(array $options)
     {
diff --git a/Neos.Flow/Classes/Security/SessionDataContainer.php b/Neos.Flow/Classes/Security/SessionDataContainer.php
index d35fb8e870..5741c6e519 100644
--- a/Neos.Flow/Classes/Security/SessionDataContainer.php
+++ b/Neos.Flow/Classes/Security/SessionDataContainer.php
@@ -4,6 +4,7 @@
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\Mvc\ActionRequest;
 use Neos\Flow\Security\Authentication\Token\SessionlessTokenInterface;
+use Neos\Flow\Security\Authentication\TokenInterface;
 
 /**
  * @Flow\Scope("session")
@@ -14,14 +15,14 @@ class SessionDataContainer
     /**
      * The current list of security tokens.
      *
-     * @var array
+     * @var array<TokenInterface>
      */
     protected $securityTokens = [];
 
     /**
      * The current list of CSRF tokens
      *
-     * @var array
+     * @var array<string,string|bool>
      */
     protected $csrfProtectionTokens = [];
 
@@ -35,7 +36,7 @@ class SessionDataContainer
     /**
      * Get the current list of security tokens.
      *
-     * @return array
+     * @return array<TokenInterface>
      */
     public function getSecurityTokens(): array
     {
@@ -45,9 +46,9 @@ public function getSecurityTokens(): array
     /**
      * Set the current list of security tokens with their data.
      *
-     * @param array $securityTokens
+     * @param array<TokenInterface> $securityTokens
      */
-    public function setSecurityTokens(array $securityTokens)
+    public function setSecurityTokens(array $securityTokens): void
     {
         foreach ($securityTokens as $token) {
             if ($token instanceof SessionlessTokenInterface) {
@@ -60,7 +61,7 @@ public function setSecurityTokens(array $securityTokens)
     /**
      * Get the current list of active CSRF tokens.
      *
-     * @return array
+     * @return array<string,string|bool>
      */
     public function getCsrfProtectionTokens(): array
     {
@@ -70,9 +71,9 @@ public function getCsrfProtectionTokens(): array
     /**
      * set the list of currently active CSRF tokens.
      *
-     * @param array $csrfProtectionTokens
+     * @param array<string,string|bool> $csrfProtectionTokens
      */
-    public function setCsrfProtectionTokens(array $csrfProtectionTokens)
+    public function setCsrfProtectionTokens(array $csrfProtectionTokens): void
     {
         $this->csrfProtectionTokens = $csrfProtectionTokens;
     }
diff --git a/Neos.Flow/Classes/Session/Aspect/LazyLoadingAspect.php b/Neos.Flow/Classes/Session/Aspect/LazyLoadingAspect.php
index 6254dd84a7..996819e604 100644
--- a/Neos.Flow/Classes/Session/Aspect/LazyLoadingAspect.php
+++ b/Neos.Flow/Classes/Session/Aspect/LazyLoadingAspect.php
@@ -29,6 +29,9 @@ class LazyLoadingAspect
     #[Flow\Inject]
     protected ?LoggerInterface $logger = null;
 
+    /**
+     * @var array<string,object>
+     */
     protected array $sessionOriginalInstances = [];
 
     public function __construct(
diff --git a/Neos.Flow/Classes/Session/Aspect/SessionObjectMethodsPointcutFilter.php b/Neos.Flow/Classes/Session/Aspect/SessionObjectMethodsPointcutFilter.php
index 1f89a3be0b..631660cb1e 100644
--- a/Neos.Flow/Classes/Session/Aspect/SessionObjectMethodsPointcutFilter.php
+++ b/Neos.Flow/Classes/Session/Aspect/SessionObjectMethodsPointcutFilter.php
@@ -22,12 +22,20 @@
 
 /**
  * Pointcut filter matching proxyable methods in objects of scope session
+ *
+ * @template ObjectRecordInstance of object
  */
 #[Flow\Scope("singleton")]
 class SessionObjectMethodsPointcutFilter implements PointcutFilterInterface
 {
+    /**
+     * @phpstan-var CompileTimeObjectManager<ObjectRecordInstance> $objectManager
+     */
     protected CompileTimeObjectManager $objectManager;
 
+    /**
+     * @phpstan-param CompileTimeObjectManager<ObjectRecordInstance> $objectManager
+     */
     public function injectObjectManager(CompileTimeObjectManager $objectManager): void
     {
         $this->objectManager = $objectManager;
@@ -37,7 +45,7 @@ public function injectObjectManager(CompileTimeObjectManager $objectManager): vo
      * Checks if the specified class and method matches against the filter
      *
      * @param string $className Name of the class to check against
-     * @param string $methodName Name of the method to check against
+     * @param ?string $methodName Name of the method to check against
      * @param string $methodDeclaringClassName Name of the class the method was originally declared in
      * @param mixed $pointcutQueryIdentifier Some identifier for this query - must at least differ from a previous identifier. Used for circular reference detection.
      * @return bool true if the class / method match, otherwise false
@@ -79,7 +87,7 @@ public function hasRuntimeEvaluationsDefinition(): bool
     /**
      * Returns runtime evaluations for a previously matched pointcut
      *
-     * @return array Runtime evaluations
+     * @return array<mixed> Runtime evaluations
      */
     public function getRuntimeEvaluationsDefinition(): array
     {
diff --git a/Neos.Flow/Classes/Session/CookieEnabledInterface.php b/Neos.Flow/Classes/Session/CookieEnabledInterface.php
index 522f07079c..c722999dad 100644
--- a/Neos.Flow/Classes/Session/CookieEnabledInterface.php
+++ b/Neos.Flow/Classes/Session/CookieEnabledInterface.php
@@ -18,5 +18,8 @@ interface CookieEnabledInterface extends SessionInterface
 {
     public function getSessionCookie(): Cookie;
 
+    /**
+     * @param array<string> $tags
+     */
     public static function createFromCookieAndSessionInformation(Cookie $sessionCookie, string $storageIdentifier, int $lastActivityTimestamp, array $tags = []): SessionInterface|CookieEnabledInterface;
 }
diff --git a/Neos.Flow/Classes/Session/Data/SessionKeyValueStore.php b/Neos.Flow/Classes/Session/Data/SessionKeyValueStore.php
index 18793fcaf5..a4ec948c1e 100644
--- a/Neos.Flow/Classes/Session/Data/SessionKeyValueStore.php
+++ b/Neos.Flow/Classes/Session/Data/SessionKeyValueStore.php
@@ -72,6 +72,9 @@ public function store(StorageIdentifier $storageIdentifier, string $key, mixed $
     {
         $entryIdentifier = $this->createEntryIdentifier($storageIdentifier, $key);
         $serializedValue = ($this->useIgBinary === true) ? igbinary_serialize($value) : serialize($value);
+        if (is_null($serializedValue)) {
+            throw new \Exception('Failed to serialize value', 1743874462);
+        }
         $valueHash = md5($serializedValue);
         $debounceHash = $this->writeDebounceHashes[$storageIdentifier->value][$key] ?? null;
         if ($debounceHash !== null && $debounceHash === $valueHash) {
@@ -90,7 +93,7 @@ public function remove(StorageIdentifier $storageIdentifier): int
         return $this->cache->flushByTag($storageIdentifier->value);
     }
 
-    private function createEntryIdentifier(StorageIdentifier $storageIdentifier, $key): string
+    private function createEntryIdentifier(StorageIdentifier $storageIdentifier, string $key): string
     {
         return $storageIdentifier->value . md5($key);
     }
diff --git a/Neos.Flow/Classes/Session/Data/SessionMetaDataStore.php b/Neos.Flow/Classes/Session/Data/SessionMetaDataStore.php
index a61eec9bff..81a21f9905 100644
--- a/Neos.Flow/Classes/Session/Data/SessionMetaDataStore.php
+++ b/Neos.Flow/Classes/Session/Data/SessionMetaDataStore.php
@@ -82,6 +82,15 @@ public function retrieve(SessionIdentifier $sessionIdentifier): ?SessionMetaData
         }
 
         if (is_array($metaDataFromCache)) {
+            if (!is_string($metaDataFromCache['storageIdentifier'] ?? null)) {
+                throw new \Exception('Missing storageIdentifier', 1743874214);
+            }
+            if (!is_int($metaDataFromCache['lastActivityTimestamp'])) {
+                throw new \Exception('Missing lastActivityTimestamp', 1743874236);
+            }
+            if (!is_array($metaDataFromCache['tags'])) {
+                throw new \Exception('Missing tags', 1743874272);
+            }
             $metaDataFromCache = SessionMetaData::createFromSessionIdentifierStringAndOldArrayCacheFormat($sessionIdentifier->value, $metaDataFromCache);
             $this->writeDebounceCache[$metaDataFromCache->sessionIdentifier->value] = $metaDataFromCache;
             return $metaDataFromCache;
@@ -104,6 +113,15 @@ public function retrieveByTag(string $tag): \Generator
                 $this->writeDebounceCache[$sessionIdentifier] = $sessionMetaData;
                 yield $sessionIdentifier => $sessionMetaData;
             } elseif (is_array($sessionMetaData)) {
+                if (!is_string($sessionMetaData['storageIdentifier'] ?? null)) {
+                    throw new \Exception('Missing storageIdentifier', 1743874214);
+                }
+                if (!is_int($sessionMetaData['lastActivityTimestamp'])) {
+                    throw new \Exception('Missing lastActivityTimestamp', 1743874236);
+                }
+                if (!is_array($sessionMetaData['tags'])) {
+                    throw new \Exception('Missing tags', 1743874272);
+                }
                 $sessionMetaData = SessionMetaData::createFromSessionIdentifierStringAndOldArrayCacheFormat($sessionIdentifier, $sessionMetaData);
                 $this->writeDebounceCache[$sessionIdentifier] = $sessionMetaData;
                 yield $sessionIdentifier => $sessionMetaData;
@@ -125,7 +143,19 @@ public function retrieveAll(): \Generator
                 $this->writeDebounceCache[$sessionIdentifier] = $sessionMetaData;
                 yield $sessionIdentifier => $sessionMetaData;
             } elseif (is_array($sessionMetaData)) {
-                $sessionMetaData = SessionMetaData::createFromSessionIdentifierStringAndOldArrayCacheFormat($sessionIdentifier, $sessionMetaData);
+                if (!is_string($sessionMetaData['storageIdentifier'] ?? null)) {
+                    throw new \Exception('Missing storageIdentifier', 1743874214);
+                }
+                if (!is_int($sessionMetaData['lastActivityTimestamp'])) {
+                    throw new \Exception('Missing lastActivityTimestamp', 1743874236);
+                }
+                if (!is_array($sessionMetaData['tags'])) {
+                    throw new \Exception('Missing tags', 1743874272);
+                }
+                $sessionMetaData = SessionMetaData::createFromSessionIdentifierStringAndOldArrayCacheFormat(
+                    $sessionIdentifier,
+                    $sessionMetaData
+                );
                 $this->writeDebounceCache[$sessionIdentifier] = $sessionMetaData;
                 yield $sessionIdentifier => $sessionMetaData;
             }
diff --git a/Neos.Flow/Classes/Session/Session.php b/Neos.Flow/Classes/Session/Session.php
index 1d67a029b9..c7296bc8ab 100644
--- a/Neos.Flow/Classes/Session/Session.php
+++ b/Neos.Flow/Classes/Session/Session.php
@@ -71,6 +71,9 @@ class Session implements CookieEnabledInterface
     protected ?string $sessionCookieSameSite = null;
     protected ?Cookie $sessionCookie = null;
     protected int $inactivityTimeout;
+    /**
+     * @var array<string>
+     */
     protected array $tags = [];
     protected int $now = 0;
     protected ?SessionMetaData $sessionMetaData = null;
@@ -91,7 +94,10 @@ public static function create(): self
         return new static();
     }
 
-    public static function createRemote(string $sessionIdentifier, string $storageIdentifier, ?int $lastActivityTimestamp = null, array $tags = []): self
+    /**
+     * @param array<string> $tags
+     */
+    public static function createRemote(string $sessionIdentifier, string $storageIdentifier, int $lastActivityTimestamp, array $tags = []): self
     {
         $session = new static();
         $session->sessionMetaData = new SessionMetaData(
@@ -114,6 +120,9 @@ public static function createRemoteFromSessionMetaData(SessionMetaData $sessionM
         return $session;
     }
 
+    /**
+     * @param array<string> $tags
+     */
     public static function createFromCookieAndSessionInformation(Cookie $sessionCookie, string $storageIdentifier, int $lastActivityTimestamp, array $tags = []): SessionInterface|CookieEnabledInterface
     {
         $session = new static();
@@ -127,6 +136,9 @@ public static function createFromCookieAndSessionInformation(Cookie $sessionCook
         return $session;
     }
 
+    /**
+     * @param array<string,mixed> $settings
+     */
     public function injectSettings(array $settings): void
     {
         $this->sessionCookieName = $settings['session']['name'];
@@ -141,6 +153,9 @@ public function injectSettings(array $settings): void
 
     public function getSessionCookie(): Cookie
     {
+        if (!$this->sessionCookie) {
+            throw new \Exception('Missing session cookie');
+        }
         return $this->sessionCookie;
     }
 
@@ -221,6 +236,9 @@ public function canBeResumed(): bool
     public function resume(): ?int
     {
         if ($this->started === false && $this->canBeResumed()) {
+            if (!$this->sessionMetaData) {
+                throw new \Exception('Cannot resume a session without metadata');
+            }
             $this->started = true;
 
             $sessionObjects = $this->sessionKeyValueStore->retrieve($this->sessionMetaData->storageIdentifier, self::FLOW_OBJECT_STORAGE_KEY);
@@ -256,7 +274,7 @@ public function resume(): ?int
      */
     public function getId(): string
     {
-        if ($this->started !== true) {
+        if ($this->started !== true || !$this->sessionMetaData) {
             throw new Exception\SessionNotStartedException('Tried to retrieve the session identifier, but the session has not been started yet.)', 1351171517);
         }
         return $this->sessionMetaData->sessionIdentifier->value;
@@ -276,6 +294,12 @@ public function renewId(): string
         if ($this->started !== true) {
             throw new Exception\SessionNotStartedException('Tried to renew the session identifier, but the session has not been started yet.', 1351182429);
         }
+        if (!$this->sessionMetaData) {
+            throw new \Exception('Missing session metadata');
+        }
+        if (!$this->sessionCookie) {
+            throw new \Exception('Missing session cookie');
+        }
         if ($this->remote === true) {
             throw new Exception\OperationNotSupportedException(sprintf('Tried to renew the session identifier on a remote session (%s).', $this->sessionMetaData->sessionIdentifier->value), 1354034230);
         }
@@ -284,6 +308,12 @@ public function renewId(): string
         $this->sessionMetaData = $this->sessionMetaData->withNewSessionIdentifier();
         $this->writeSessionMetaDataCacheEntry();
 
+        if (!$this->sessionMetaData) {
+            throw new \Exception('Missing session metadata');
+        }
+        if (!$this->sessionCookie) {
+            throw new \Exception('Missing session cookie');
+        }
         $this->sessionCookie->setValue($this->sessionMetaData->sessionIdentifier->value);
         return $this->sessionMetaData->sessionIdentifier->value;
     }
@@ -297,7 +327,7 @@ public function renewId(): string
      */
     public function getData(string $key): mixed
     {
-        if ($this->started !== true) {
+        if ($this->started !== true || !$this->sessionMetaData) {
             throw new Exception\SessionNotStartedException('Tried to get session data, but the session has not been started yet.', 1351162255);
         }
         return $this->sessionKeyValueStore->retrieve($this->sessionMetaData->storageIdentifier, $key);
@@ -312,7 +342,7 @@ public function getData(string $key): mixed
      */
     public function hasKey(string $key): bool
     {
-        if ($this->started !== true) {
+        if ($this->started !== true || !$this->sessionMetaData) {
             throw new Exception\SessionNotStartedException('Tried to check a session data entry, but the session has not been started yet.', 1352488661);
         }
         return $this->sessionKeyValueStore->has($this->sessionMetaData->storageIdentifier, $key);
@@ -332,7 +362,7 @@ public function hasKey(string $key): bool
      */
     public function putData(string $key, mixed $data): void
     {
-        if ($this->started !== true) {
+        if ($this->started !== true || !$this->sessionMetaData) {
             throw new Exception\SessionNotStartedException('Tried to create a session data entry, but the session has not been started yet.', 1351162259);
         }
         if (is_resource($data)) {
@@ -354,7 +384,7 @@ public function putData(string $key, mixed $data): void
      */
     public function getLastActivityTimestamp(): int
     {
-        if ($this->started !== true) {
+        if ($this->started !== true || !$this->sessionMetaData) {
             throw new Exception\SessionNotStartedException('Tried to retrieve the last activity timestamp of a session which has not been started yet.', 1354290378);
         }
         return $this->sessionMetaData->lastActivityTimestamp;
@@ -378,9 +408,9 @@ public function addTag(string $tag): void
             throw new Exception\SessionNotStartedException('Tried to tag a session which has not been started yet.', 1355143533);
         }
         if (!$this->sessionMetaDataStore->isValidSessionTag($tag)) {
-            throw new \InvalidArgumentException(sprintf('The tag used for tagging session %s contained invalid characters. Make sure it matches this regular expression: "%s"', $this->sessionMetaData->sessionIdentifier->value, FrontendInterface::PATTERN_TAG));
+            throw new \InvalidArgumentException(sprintf('The tag used for tagging session %s contained invalid characters. Make sure it matches this regular expression: "%s"', $this->sessionMetaData?->sessionIdentifier->value ?: '', FrontendInterface::PATTERN_TAG));
         }
-        $this->sessionMetaData = $this->sessionMetaData->withAddedTag($tag);
+        $this->sessionMetaData = $this->sessionMetaData?->withAddedTag($tag);
     }
 
     /**
@@ -396,14 +426,14 @@ public function removeTag(string $tag): void
         if ($this->started !== true) {
             throw new Exception\SessionNotStartedException('Tried to tag a session which has not been started yet.', 1355150140);
         }
-        $this->sessionMetaData = $this->sessionMetaData->withRemovedTag($tag);
+        $this->sessionMetaData = $this->sessionMetaData?->withRemovedTag($tag);
     }
 
 
     /**
      * Returns the tags this session has been tagged with.
      *
-     * @return array The tags or an empty array if there aren't any
+     * @return array<string> The tags or an empty array if there aren't any
      * @throws Exception\SessionNotStartedException
      * @api
      */
@@ -412,7 +442,7 @@ public function getTags(): array
         if ($this->started !== true) {
             throw new Exception\SessionNotStartedException('Tried to retrieve tags from a session which has not been started yet.', 1355141501);
         }
-        return $this->sessionMetaData->tags;
+        return $this->sessionMetaData?->tags ?: [];
     }
 
     /**
@@ -428,7 +458,7 @@ public function touch(): void
 
         // Only makes sense for remote sessions because the currently active session
         // will be updated on shutdown anyway:
-        if ($this->remote === true) {
+        if ($this->remote === true && $this->sessionMetaData) {
             $this->sessionMetaData = $this->sessionMetaData->withLastActivityTimestamp($this->now);
             $this->writeSessionMetaDataCacheEntry();
         }
@@ -461,12 +491,14 @@ public function destroy(?string $reason = null): void
         }
 
         if ($this->remote !== true) {
-            $this->sessionCookie->expire();
+            $this->sessionCookie?->expire();
         }
 
-        $this->sessionMetaDataStore->remove($this->sessionMetaData);
-        $this->sessionKeyValueStore->remove($this->sessionMetaData->storageIdentifier);
-        $this->sessionMetaData = null;
+        if ($this->sessionMetaData) {
+            $this->sessionMetaDataStore->remove($this->sessionMetaData);
+            $this->sessionKeyValueStore->remove($this->sessionMetaData->storageIdentifier);
+            $this->sessionMetaData = null;
+        }
         $this->started = false;
     }
 
@@ -482,8 +514,12 @@ public function destroy(?string $reason = null): void
     public function shutdownObject(): void
     {
         if ($this->started === true && $this->remote === false) {
-            if ($this->sessionMetaDataStore->has($this->sessionMetaData->sessionIdentifier)) {
-                $this->sessionKeyValueStore->store($this->sessionMetaData->storageIdentifier, self::FLOW_OBJECT_STORAGE_KEY, $this->objectManager->getSessionInstances() ?? []);
+            if ($this->sessionMetaData && $this->sessionMetaDataStore->has($this->sessionMetaData->sessionIdentifier)) {
+                $this->sessionKeyValueStore->store(
+                    $this->sessionMetaData->storageIdentifier,
+                    self::FLOW_OBJECT_STORAGE_KEY,
+                    $this->objectManager->getSessionInstances()
+                );
                 $this->writeSessionMetaDataCacheEntry();
             }
             $this->started = false;
@@ -497,11 +533,11 @@ public function shutdownObject(): void
      */
     protected function autoExpire(): bool
     {
-        $lastActivitySecondsAgo = $this->now - $this->sessionMetaData->lastActivityTimestamp;
+        $lastActivitySecondsAgo = $this->now - ($this->sessionMetaData?->lastActivityTimestamp ?: 0);
         $expired = false;
         if ($this->inactivityTimeout !== 0 && $lastActivitySecondsAgo > $this->inactivityTimeout) {
             $this->started = true;
-            $this->destroy(sprintf('Session %s was inactive for %s seconds, more than the configured timeout of %s seconds.', $this->sessionMetaData->sessionIdentifier->value, $lastActivitySecondsAgo, $this->inactivityTimeout));
+            $this->destroy(sprintf('Session %s was inactive for %s seconds, more than the configured timeout of %s seconds.', $this->sessionMetaData?->sessionIdentifier->value ?: '', $lastActivitySecondsAgo, $this->inactivityTimeout));
             $expired = true;
         }
         return $expired;
@@ -521,6 +557,8 @@ protected function autoExpire(): bool
      */
     protected function writeSessionMetaDataCacheEntry(): void
     {
-        $this->sessionMetaDataStore->store($this->sessionMetaData);
+        if ($this->sessionMetaData) {
+            $this->sessionMetaDataStore->store($this->sessionMetaData);
+        }
     }
 }
diff --git a/Neos.Flow/Classes/Session/SessionInterface.php b/Neos.Flow/Classes/Session/SessionInterface.php
index 791f21debf..b9c8b51485 100644
--- a/Neos.Flow/Classes/Session/SessionInterface.php
+++ b/Neos.Flow/Classes/Session/SessionInterface.php
@@ -107,7 +107,7 @@ public function removeTag(string $tag): void;
     /**
      * Returns the tags this session has been tagged with.
      *
-     * @return array The tags or an empty array if there aren't any
+     * @return array<string> The tags or an empty array if there aren't any
      * @throws Exception\SessionNotStartedException
      * @api
      */
diff --git a/Neos.Flow/Classes/Session/SessionManager.php b/Neos.Flow/Classes/Session/SessionManager.php
index cdf8d89a90..c6629baccd 100644
--- a/Neos.Flow/Classes/Session/SessionManager.php
+++ b/Neos.Flow/Classes/Session/SessionManager.php
@@ -27,6 +27,10 @@
 class SessionManager implements SessionManagerInterface
 {
     protected ?SessionInterface $currentSession = null;
+
+    /**
+     * @var array<string,Session>
+     */
     protected array $remoteSessions = [];
 
     public function __construct(
@@ -139,7 +143,7 @@ public function getActiveSessions(): array
      * Returns all sessions which are tagged by the specified tag.
      *
      * @param string $tag A valid Cache Frontend tag
-     * @return array A collection of Session objects or an empty array if tag did not match
+     * @return array<SessionInterface> A collection of Session objects or an empty array if tag did not match
      * @throws NotSupportedByBackendException
      * @api
      */
@@ -195,10 +199,8 @@ public function collectGarbage(): ?int
         foreach ($this->sessionMetaDataStore->retrieveAll() as $sessionMetadata) {
             $lastActivitySecondsAgo = $now - $sessionMetadata->lastActivityTimestamp;
             if ($lastActivitySecondsAgo > $this->inactivityTimeout) {
-                if ($sessionMetadata->lastActivityTimestamp !== null) {
-                    $this->sessionKeyValueStore->remove($sessionMetadata->storageIdentifier);
-                    $sessionRemovalCount++;
-                }
+                $this->sessionKeyValueStore->remove($sessionMetadata->storageIdentifier);
+                $sessionRemovalCount++;
                 $this->sessionMetaDataStore->remove($sessionMetadata);
             }
             if ($sessionRemovalCount >= $this->garbageCollectionMaximumPerRun) {
@@ -223,7 +225,7 @@ public function collectGarbage(): ?int
     public function shutdownObject(): void
     {
         if (str_contains((string)$this->garbageCollectionProbability, '.')) {
-            $decimals = strlen(strrchr((string)$this->garbageCollectionProbability, '.')) - 1;
+            $decimals = strlen(strrchr((string)$this->garbageCollectionProbability, '.') ?: '') - 1;
             $factor = $decimals * 10;
         } else {
             $factor = 1;
diff --git a/Neos.Flow/Classes/Session/SessionManagerInterface.php b/Neos.Flow/Classes/Session/SessionManagerInterface.php
index de71da87fd..1455968e47 100644
--- a/Neos.Flow/Classes/Session/SessionManagerInterface.php
+++ b/Neos.Flow/Classes/Session/SessionManagerInterface.php
@@ -51,7 +51,7 @@ public function getActiveSessions(): array;
      * Returns all sessions which are tagged by the specified tag.
      *
      * @param string $tag A valid Cache Frontend tag
-     * @return array A collection of Session objects or an empty array if tag did not match
+     * @return array<SessionInterface> A collection of Session objects or an empty array if tag did not match
      * @api
      */
     public function getSessionsByTag(string $tag): array;
diff --git a/Neos.Flow/Classes/Session/TransientSession.php b/Neos.Flow/Classes/Session/TransientSession.php
index 0e15bb8231..ad9fbdcb6f 100644
--- a/Neos.Flow/Classes/Session/TransientSession.php
+++ b/Neos.Flow/Classes/Session/TransientSession.php
@@ -26,8 +26,14 @@ class TransientSession implements SessionInterface
 {
     protected string $sessionId;
     protected bool $started = false;
+    /**
+     * @var array<string,mixed>
+     */
     protected array $data = [];
     protected ?int $lastActivityTimestamp = null;
+    /**
+     * @var array<string,bool>
+     */
     protected array $tags;
 
     public function isStarted(): bool
@@ -165,6 +171,7 @@ public function getLastActivityTimestamp(): int
         if ($this->lastActivityTimestamp === null) {
             $this->touch();
         }
+        /** @phpstan-ignore return.type (touch() initializes the timestamp) */
         return $this->lastActivityTimestamp;
     }
 
@@ -185,7 +192,6 @@ public function touch(): void
      * @param string $tag The tag – must match be a valid cache frontend tag
      * @return void
      * @throws Exception\SessionNotStartedException
-     * @throws \InvalidArgumentException
      * @api
      */
     public function addTag(string $tag): void
@@ -217,7 +223,7 @@ public function removeTag(string $tag): void
     /**
      * Returns the tags this session has been tagged with.
      *
-     * @return array The tags or an empty array if there aren't any
+     * @return array<int,string> The tags or an empty array if there aren't any
      * @throws Exception\SessionNotStartedException
      * @api
      */
diff --git a/Neos.Flow/Classes/SignalSlot/Dispatcher.php b/Neos.Flow/Classes/SignalSlot/Dispatcher.php
index b802e14517..947690d4d3 100644
--- a/Neos.Flow/Classes/SignalSlot/Dispatcher.php
+++ b/Neos.Flow/Classes/SignalSlot/Dispatcher.php
@@ -24,18 +24,21 @@
  */
 class Dispatcher
 {
-    /**
-     * @var ObjectManagerInterface
-     */
-    protected $objectManager;
+    protected ?ObjectManagerInterface $objectManager = null;
 
     /**
      * Information about all slots connected a certain signal.
      * Indexed by [$signalClassName][$signalMethodName] and then numeric with an
      * array of information about the slot
-     * @var array
+     * @var array<class-string,array<string,array<int,array{
+     *     class: ?class-string,
+     *     method: string,
+     *     object: ?object,
+     *     passSignalInformation: bool,
+     *     useSignalInformationObject: bool,
+     * }>>>
      */
-    protected $slots = [];
+    protected array $slots = [];
 
     /**
      * Injects the object manager
@@ -56,7 +59,7 @@ public function injectObjectManager(ObjectManagerInterface $objectManager): void
      * When $passSignalInformation is true, the slot will be passed a string (EmitterClassName::signalName) as the last
      * parameter.
      *
-     * @param string $signalClassName Name of the class containing the signal
+     * @param class-string $signalClassName Name of the class containing the signal
      * @param string $signalName Name of the signal
      * @param mixed $slotClassNameOrObject Name of the class containing the slot or the instantiated class or a Closure object
      * @param string $slotMethodName Name of the method to be used as a slot. If $slotClassNameOrObject is a Closure object, this parameter is ignored
@@ -78,7 +81,7 @@ public function connect(string $signalClassName, string $signalName, $slotClassN
      *
      * The slot will be passed a an instance of SignalInformation as the sole parameter.
      *
-     * @param string $signalClassName Name of the class containing the signal
+     * @param class-string $signalClassName Name of the class containing the signal
      * @param string $signalName Name of the signal
      * @param mixed $slotClassNameOrObject Name of the class containing the slot or the instantiated class or a Closure object
      * @param string $slotMethodName Name of the method to be used as a slot. If $slotClassNameOrObject is a Closure object, this parameter is ignored
@@ -94,7 +97,7 @@ public function wire(string $signalClassName, string $signalName, $slotClassName
     }
 
     /**
-     * @param string $signalClassName
+     * @param class-string $signalClassName
      * @param string $signalName
      * @param mixed $slotClassNameOrObject
      * @param string $slotMethodName
@@ -137,7 +140,7 @@ private function connectSignalToSlot(string $signalClassName, string $signalName
      *
      * @param string $signalClassName Name of the class containing the signal
      * @param string $signalName Name of the signal
-     * @param array $signalArguments arguments passed to the signal method
+     * @param array<mixed> $signalArguments arguments passed to the signal method
      * @return void
      * @throws Exception\InvalidSlotException if the slot is not valid
      * @api
@@ -153,37 +156,48 @@ public function dispatch(string $signalClassName, string $signalName, array $sig
             if (isset($slotInformation['object'])) {
                 $object = $slotInformation['object'];
             } elseif (strpos($slotInformation['method'], '::') === 0) {
-                if (!isset($this->objectManager)) {
+                if ($this->objectManager === null) {
                     if (is_callable($slotInformation['class'] . $slotInformation['method'])) {
                         $object = $slotInformation['class'];
                     } else {
                         throw new Exception\InvalidSlotException(sprintf('Cannot dispatch %s::%s to class %s. The object manager is not yet available in the Signal Slot Dispatcher and therefore it cannot dispatch classes.', $signalClassName, $signalName, $slotInformation['class']), 1298113624);
                     }
                 } else {
+                    if ($slotInformation['class'] === null) {
+                        throw new Exception\InvalidSlotException('Slot class is undefined.', 1743958214);
+                    }
                     $object = $this->objectManager->getClassNameByObjectName($slotInformation['class']);
                 }
                 $slotInformation['method'] = substr($slotInformation['method'], 2);
             } else {
-                if (!isset($this->objectManager)) {
+                if ($this->objectManager === null) {
                     throw new Exception\InvalidSlotException(sprintf('Cannot dispatch %s::%s to class %s. The object manager is not yet available in the Signal Slot Dispatcher and therefore it cannot dispatch classes.', $signalClassName, $signalName, $slotInformation['class']), 1298113624);
                 }
+                if ($slotInformation['class'] === null) {
+                    throw new Exception\InvalidSlotException('Slot class is undefined.', 1743958214);
+                }
                 if (!$this->objectManager->isRegistered($slotInformation['class'])) {
                     throw new Exception\InvalidSlotException('The given class "' . $slotInformation['class'] . '" is not a registered object.', 1245673367);
                 }
                 $object = $this->objectManager->get($slotInformation['class']);
             }
-            if (!method_exists($object, $slotInformation['method'])) {
+            if (is_object($object) && !method_exists($object, $slotInformation['method'])) {
                 throw new Exception\InvalidSlotException('The slot method ' . get_class($object) . '->' . $slotInformation['method'] . '() does not exist.', 1245673368);
             }
 
+            $callable = [$object, $slotInformation['method']];
+            if (!is_callable($callable)) {
+                throw new \Exception('Invalid slot method ' . $slotInformation['method'], 1743955562);
+            }
+
             if ($slotInformation['useSignalInformationObject'] === true) {
-                call_user_func([$object, $slotInformation['method']], new SignalInformation($signalClassName, $signalName, $finalSignalArguments));
+                call_user_func($callable, new SignalInformation($signalClassName, $signalName, $finalSignalArguments));
             } else {
                 if ($slotInformation['passSignalInformation'] === true) {
                     $finalSignalArguments[] = $signalClassName . '::' . $signalName;
                 }
                 // Need to use call_user_func_array here, because $object may be the class name when the slot is a static method
-                call_user_func_array([$object, $slotInformation['method']], $finalSignalArguments);
+                call_user_func_array($callable, $finalSignalArguments);
             }
         }
     }
@@ -191,9 +205,15 @@ public function dispatch(string $signalClassName, string $signalName, array $sig
     /**
      * Returns all slots which are connected with the given signal
      *
-     * @param string $signalClassName Name of the class containing the signal
+     * @param class-string $signalClassName Name of the class containing the signal
      * @param string $signalName Name of the signal
-     * @return array An array of arrays with slot information
+     * @return array<int,array{
+     *      class: ?class-string,
+     *      method: string,
+     *      object: ?object,
+     *      passSignalInformation: bool,
+     *      useSignalInformationObject: bool,
+     *  }> An array of arrays with slot information
      * @api
      */
     public function getSlots(string $signalClassName, string $signalName): array
@@ -204,7 +224,13 @@ public function getSlots(string $signalClassName, string $signalName): array
     /**
      * Returns all signals with its slots
      *
-     * @return array An array of arrays with slot information
+     * @return array<class-string,array<string,array<int,array{
+     *      class: ?class-string,
+     *      method: string,
+     *      object: ?object,
+     *      passSignalInformation: bool,
+     *      useSignalInformationObject: bool,
+     *  }>>> An array of arrays with slot information
      * @api
      */
     public function getSignals(): array
diff --git a/Neos.Flow/Classes/SignalSlot/SignalInformation.php b/Neos.Flow/Classes/SignalSlot/SignalInformation.php
index 650b133a76..3ad58347bc 100644
--- a/Neos.Flow/Classes/SignalSlot/SignalInformation.php
+++ b/Neos.Flow/Classes/SignalSlot/SignalInformation.php
@@ -35,10 +35,13 @@ final class SignalInformation
     protected $signalName;
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $signalArguments;
 
+    /**
+     * @param array<mixed> $signalArguments
+     */
     public function __construct(string $signalClassName, string $signalName, array $signalArguments)
     {
         $this->signalClassName = $signalClassName;
@@ -56,6 +59,9 @@ public function getSignalName(): string
         return $this->signalName;
     }
 
+    /**
+     * @return array<mixed>
+     */
     public function getSignalArguments(): array
     {
         return $this->signalArguments;
diff --git a/Neos.Flow/Classes/Utility/Algorithms.php b/Neos.Flow/Classes/Utility/Algorithms.php
index 9991b4cfe4..fb46608466 100644
--- a/Neos.Flow/Classes/Utility/Algorithms.php
+++ b/Neos.Flow/Classes/Utility/Algorithms.php
@@ -36,7 +36,7 @@ class Algorithms
      */
     public static function generateUUID(): string
     {
-        if (is_callable('uuid_create')) {
+        if (function_exists('uuid_create')) {
             return strtolower(uuid_create(UUID_TYPE_RANDOM));
         }
 
diff --git a/Neos.Flow/Classes/Utility/Environment.php b/Neos.Flow/Classes/Utility/Environment.php
index 44787d3f87..f5e20e39eb 100644
--- a/Neos.Flow/Classes/Utility/Environment.php
+++ b/Neos.Flow/Classes/Utility/Environment.php
@@ -16,7 +16,6 @@
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\Core\ApplicationContext;
 use Neos\Flow\Core\Bootstrap;
-use Neos\Flow\Error\Exception as ErrorException;
 use Neos\Flow\Utility\Exception as UtilityException;
 use Neos\Flow\Mvc\ActionRequest;
 use Neos\Utility\Exception\FilesException;
@@ -140,18 +139,15 @@ public static function composeTemporaryDirectoryName(string $temporaryDirectoryB
      *
      * @param string $temporaryDirectoryBase Full path to the base for the temporary directory
      * @return string The full path to the temporary directory
-     * @throws UtilityException if the temporary directory could not be created or is not writable
+     * @throws FilesException if the temporary directory could not be created
+     * @throws UtilityException if the temporary directory is not writable
      */
     protected function createTemporaryDirectory(string $temporaryDirectoryBase): string
     {
         $temporaryDirectory = self::composeTemporaryDirectoryName($temporaryDirectoryBase, $this->context);
 
         if (!is_dir($temporaryDirectory) && !is_link($temporaryDirectory)) {
-            try {
-                Files::createDirectoryRecursively($temporaryDirectory);
-            } catch (ErrorException $exception) {
-                throw new UtilityException('The temporary directory "' . $temporaryDirectory . '" could not be created. Please make sure permissions are correct for this path or define another temporary directory in your Settings.yaml with the path "Neos.Flow.utility.environment.temporaryDirectoryBase".', 1335382361);
-            }
+            Files::createDirectoryRecursively($temporaryDirectory);
         }
 
         if (!is_writable($temporaryDirectory)) {
diff --git a/Neos.Flow/Classes/Validation/Validator/AbstractCompositeValidator.php b/Neos.Flow/Classes/Validation/Validator/AbstractCompositeValidator.php
index 4803782fa4..dba8d72acb 100644
--- a/Neos.Flow/Classes/Validation/Validator/AbstractCompositeValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/AbstractCompositeValidator.php
@@ -24,29 +24,29 @@ abstract class AbstractCompositeValidator implements ObjectValidatorInterface, \
     /**
      * This contains the supported options, their default values and descriptions.
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $supportedOptions = [];
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $options = [];
 
     /**
-     * @var \SplObjectStorage
+     * @var \SplObjectStorage<ValidatorInterface,mixed>
      */
     protected $validators;
 
     /**
-     * @var \SplObjectStorage
+     * @var \SplObjectStorage<object,mixed>
      */
     protected $validatedInstancesContainer;
 
     /**
      * Constructs the composite validator and sets validation options
      *
-     * @param array $options Options for the validator
+     * @param array<mixed> $options Options for the validator
      * @api
      * @throws InvalidValidationOptionsException
      */
@@ -84,7 +84,7 @@ function ($value) {
     /**
      * Allows to set a container to keep track of validated instances.
      *
-     * @param \SplObjectStorage $validatedInstancesContainer A container to keep track of validated instances
+     * @param \SplObjectStorage<object,mixed> $validatedInstancesContainer A container to keep track of validated instances
      * @return void
      * @api
      */
@@ -102,7 +102,7 @@ public function setValidatedInstancesContainer(\SplObjectStorage $validatedInsta
      */
     public function addValidator(ValidatorInterface $validator)
     {
-        if ($validator instanceof ObjectValidatorInterface && isset($this->validatedInstancesContainer)) {
+        if ($validator instanceof ObjectValidatorInterface) {
             $validator->setValidatedInstancesContainer($this->validatedInstancesContainer);
         }
         $this->validators->attach($validator);
@@ -115,7 +115,7 @@ public function addValidator(ValidatorInterface $validator)
      * @throws NoSuchValidatorException
      * @api
      */
-    public function removeValidator(ValidatorInterface $validator)
+    public function removeValidator(ValidatorInterface $validator): void
     {
         if (!$this->validators->contains($validator)) {
             throw new NoSuchValidatorException('Cannot remove validator because its not in the conjunction.', 1207020177);
@@ -137,7 +137,7 @@ public function count(): int
     /**
      * Returns the child validators of this Composite Validator
      *
-     * @return \SplObjectStorage
+     * @return \SplObjectStorage<ValidatorInterface,mixed>
      */
     public function getValidators()
     {
@@ -147,7 +147,7 @@ public function getValidators()
     /**
      * Returns the options for this validator
      *
-     * @return array
+     * @return array<mixed>
      */
     public function getOptions()
     {
diff --git a/Neos.Flow/Classes/Validation/Validator/AbstractValidator.php b/Neos.Flow/Classes/Validation/Validator/AbstractValidator.php
index 7a11ff35e9..9f91868935 100644
--- a/Neos.Flow/Classes/Validation/Validator/AbstractValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/AbstractValidator.php
@@ -41,17 +41,17 @@ abstract class AbstractValidator implements ValidatorInterface
      * 2 => type
      * 3 => required (boolean, optional)
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $supportedOptions = [];
 
     /**
-     * @var array
+     * @var array<mixed>
      */
     protected $options = [];
 
     /**
-     * @var ErrorResult
+     * @var ErrorResult|null
      */
     private $result;
 
@@ -63,7 +63,7 @@ abstract class AbstractValidator implements ValidatorInterface
     /**
      * Constructs the validator and sets validation options
      *
-     * @param array $options Options for the validator
+     * @param array<mixed> $options Options for the validator
      * @throws InvalidValidationOptionsException if unsupported options are found
      * @api
      */
@@ -117,7 +117,7 @@ protected function pushResult()
     /**
      * Pop and return the current Result from the stack and make $this->result point to the last Result again.
      * @since Flow 4.3
-     * @return ErrorResult
+     * @return ErrorResult|null
      */
     protected function popResult()
     {
@@ -143,7 +143,7 @@ protected function getResult()
      * the Error Messages object which occurred.
      *
      * @param mixed $value The value that should be validated
-     * @return ErrorResult
+     * @return ErrorResult|null
      * @throws InvalidValidationOptionsException
      * @api
      */
@@ -171,19 +171,22 @@ abstract protected function isValid($value);
      *
      * @param string $message The error message
      * @param integer $code The error code (a unix timestamp)
-     * @param array $arguments Arguments to be replaced in message
+     * @param array<mixed> $arguments Arguments to be replaced in message
      * @return void
      * @api
      */
     protected function addError($message, $code, array $arguments = [])
     {
+        if ($this->result === null) {
+            $this->result = new ErrorResult();
+        }
         $this->result->addError(new ValidationError($message, $code, $arguments));
     }
 
     /**
      * Returns the options of this validator
      *
-     * @return array
+     * @return array<mixed>
      */
     public function getOptions()
     {
diff --git a/Neos.Flow/Classes/Validation/Validator/BooleanValueValidator.php b/Neos.Flow/Classes/Validation/Validator/BooleanValueValidator.php
index be9ac2833f..c0d773440c 100644
--- a/Neos.Flow/Classes/Validation/Validator/BooleanValueValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/BooleanValueValidator.php
@@ -22,7 +22,7 @@
 class BooleanValueValidator extends AbstractValidator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'expectedValue' => [true, 'The expected boolean value', 'boolean']
diff --git a/Neos.Flow/Classes/Validation/Validator/CollectionValidator.php b/Neos.Flow/Classes/Validation/Validator/CollectionValidator.php
index e02bf51efb..85376bc5ca 100644
--- a/Neos.Flow/Classes/Validation/Validator/CollectionValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/CollectionValidator.php
@@ -22,7 +22,7 @@
 class CollectionValidator extends GenericObjectValidator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'elementValidator' => [null, 'The validator type to use for the collection elements', 'string'],
@@ -52,7 +52,7 @@ protected function isValid($value)
     {
         if ($value instanceof \Doctrine\Common\Collections\AbstractLazyCollection && !$value->isInitialized()) {
             return;
-        } elseif ((is_object($value) && !TypeHandling::isCollectionType(get_class($value))) && !is_array($value)) {
+        } elseif (is_object($value) && !TypeHandling::isCollectionType(get_class($value))) {
             $this->addError('The given subject was not a collection.', 1317204797);
             return;
         } elseif (is_object($value) && $this->isValidatedAlready($value)) {
@@ -75,7 +75,9 @@ protected function isValid($value)
                 $collectionElementValidator->setValidatedInstancesContainer($this->validatedInstancesContainer);
             }
 
-            $this->getResult()->forProperty($index)->merge($collectionElementValidator->validate($collectionElement));
+            if ($this->getResult() && $collectionElementValidator) {
+                $this->getResult()->forProperty($index)->merge($collectionElementValidator->validate($collectionElement));
+            }
         }
     }
 }
diff --git a/Neos.Flow/Classes/Validation/Validator/ConjunctionValidator.php b/Neos.Flow/Classes/Validation/Validator/ConjunctionValidator.php
index 1dc9ff520b..c2bbd67562 100644
--- a/Neos.Flow/Classes/Validation/Validator/ConjunctionValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/ConjunctionValidator.php
@@ -25,7 +25,7 @@ class ConjunctionValidator extends AbstractCompositeValidator
      * Every validator has to be valid, to make the whole conjunction valid.
      *
      * @param mixed $value The value that should be validated
-     * @return ErrorResult
+     * @return ErrorResult|null
      * @api
      */
     public function validate($value)
diff --git a/Neos.Flow/Classes/Validation/Validator/CountValidator.php b/Neos.Flow/Classes/Validation/Validator/CountValidator.php
index 97a2b8cc7d..9e80afb73e 100644
--- a/Neos.Flow/Classes/Validation/Validator/CountValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/CountValidator.php
@@ -20,7 +20,7 @@
 class CountValidator extends AbstractValidator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'minimum' => [0, 'The minimum count to accept', 'integer'],
diff --git a/Neos.Flow/Classes/Validation/Validator/DateTimeRangeValidator.php b/Neos.Flow/Classes/Validation/Validator/DateTimeRangeValidator.php
index cf5266d104..1e9a2fece4 100644
--- a/Neos.Flow/Classes/Validation/Validator/DateTimeRangeValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/DateTimeRangeValidator.php
@@ -21,7 +21,7 @@
 class DateTimeRangeValidator extends AbstractValidator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'latestDate' => [null, 'The latest date to accept', 'string'],
diff --git a/Neos.Flow/Classes/Validation/Validator/DateTimeValidator.php b/Neos.Flow/Classes/Validation/Validator/DateTimeValidator.php
index db14ba9293..ebd10f2c2d 100644
--- a/Neos.Flow/Classes/Validation/Validator/DateTimeValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/DateTimeValidator.php
@@ -23,7 +23,7 @@
 class DateTimeValidator extends AbstractValidator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'locale' => [null, 'The locale to use for date parsing', 'string|Locale'],
diff --git a/Neos.Flow/Classes/Validation/Validator/DisjunctionValidator.php b/Neos.Flow/Classes/Validation/Validator/DisjunctionValidator.php
index 605a2c69c5..6373ac2c47 100644
--- a/Neos.Flow/Classes/Validation/Validator/DisjunctionValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/DisjunctionValidator.php
@@ -28,7 +28,7 @@ class DisjunctionValidator extends AbstractCompositeValidator
      * Errors are only returned if all validators failed.
      *
      * @param mixed $value The value that should be validated
-     * @return ErrorResult
+     * @return ErrorResult|null
      * @api
      */
     public function validate($value)
diff --git a/Neos.Flow/Classes/Validation/Validator/EmailAddressValidator.php b/Neos.Flow/Classes/Validation/Validator/EmailAddressValidator.php
index bf9609d4cb..2d814e1bc8 100644
--- a/Neos.Flow/Classes/Validation/Validator/EmailAddressValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/EmailAddressValidator.php
@@ -27,7 +27,7 @@
 class EmailAddressValidator extends AbstractValidator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'strict' => [false, 'Whether to fail validation on RFC warnings', 'bool'],
diff --git a/Neos.Flow/Classes/Validation/Validator/FileExtensionValidator.php b/Neos.Flow/Classes/Validation/Validator/FileExtensionValidator.php
index c3534f7ff4..fd72ac0bb5 100644
--- a/Neos.Flow/Classes/Validation/Validator/FileExtensionValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/FileExtensionValidator.php
@@ -31,7 +31,7 @@ class FileExtensionValidator extends AbstractValidator
      * 2 => type
      * 3 => required (boolean, optional)
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'allowedExtensions' => [[], 'Array of allowed file extensions', 'array', true]
@@ -58,9 +58,9 @@ protected function isValid($value)
             return;
         }
 
-        $fileExtension =  pathinfo((string)$filename, PATHINFO_EXTENSION);
+        $fileExtension = pathinfo((string)$filename, PATHINFO_EXTENSION);
 
-        if ($fileExtension === null || $fileExtension === '') {
+        if ($fileExtension === '') {
             $this->addError('The file has no file extension.', 1677934932);
             return;
         }
diff --git a/Neos.Flow/Classes/Validation/Validator/FileSizeValidator.php b/Neos.Flow/Classes/Validation/Validator/FileSizeValidator.php
index 13283f7624..7507d821ad 100644
--- a/Neos.Flow/Classes/Validation/Validator/FileSizeValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/FileSizeValidator.php
@@ -31,7 +31,7 @@ class FileSizeValidator extends AbstractValidator
      * 2 => type
      * 3 => required (boolean, optional)
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'minimum' => [null, 'Minimum allowed filesize in bytes', 'integer', false],
diff --git a/Neos.Flow/Classes/Validation/Validator/GenericObjectValidator.php b/Neos.Flow/Classes/Validation/Validator/GenericObjectValidator.php
index e211fc144b..bd38927e04 100644
--- a/Neos.Flow/Classes/Validation/Validator/GenericObjectValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/GenericObjectValidator.php
@@ -23,26 +23,26 @@
 class GenericObjectValidator extends AbstractValidator implements ObjectValidatorInterface
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'skipUnInitializedProxies' => [false, 'Whether proxies not yet initialized should be skipped during validation', 'boolean']
     ];
 
     /**
-     * @var array
+     * @var array<string,\SplObjectStorage<ValidatorInterface,mixed>>
      */
     protected $propertyValidators = [];
 
     /**
-     * @var \SplObjectStorage
+     * @var \SplObjectStorage<object,mixed>
      */
     protected $validatedInstancesContainer;
 
     /**
      * Allows to set a container to keep track of validated instances.
      *
-     * @param \SplObjectStorage $validatedInstancesContainer A container to keep track of validated instances
+     * @param \SplObjectStorage<object,mixed> $validatedInstancesContainer A container to keep track of validated instances
      * @return void
      * @api
      */
@@ -77,16 +77,17 @@ protected function isValid($object)
             $propertyValue = $this->getPropertyValue($object, $propertyName);
             $result = $this->checkProperty($propertyValue, $validators);
             if ($result !== null) {
-                $this->getResult()->forProperty($propertyName)->merge($result);
+                if ($this->getResult()) {
+                    $this->getResult()->forProperty($propertyName)->merge($result);
+                }
             }
         }
     }
 
     /**
-     * @param $object
      * @return boolean
      */
-    protected function isUninitializedProxy($object)
+    protected function isUninitializedProxy(object $object)
     {
         return ($object instanceof DoctrineProxy && $object->__isInitialized() === false);
     }
@@ -132,7 +133,7 @@ protected function getPropertyValue($object, $propertyName)
      * found errors to the $messages object.
      *
      * @param mixed $value The value to be validated
-     * @param array $validators The validators to be called on the value
+     * @param array<ValidatorInterface>|\SplObjectStorage<ValidatorInterface,mixed> $validators The validators to be called on the value
      * @return NULL|ErrorResult
      */
     protected function checkProperty($value, $validators)
@@ -162,10 +163,12 @@ protected function checkProperty($value, $validators)
      * @return void
      * @api
      */
-    public function addPropertyValidator($propertyName, ValidatorInterface $validator)
+    public function addPropertyValidator(string $propertyName, ValidatorInterface $validator)
     {
         if (!isset($this->propertyValidators[$propertyName])) {
-            $this->propertyValidators[$propertyName] = new \SplObjectStorage();
+            /** @var \SplObjectStorage<ValidatorInterface,mixed> $storage */
+            $storage = new \SplObjectStorage();
+            $this->propertyValidators[$propertyName] = $storage;
         }
         $this->propertyValidators[$propertyName]->attach($validator);
     }
@@ -173,13 +176,18 @@ public function addPropertyValidator($propertyName, ValidatorInterface $validato
     /**
      * Returns all property validators - or only validators of the specified property
      *
-     * @param string $propertyName Name of the property to return validators for
-     * @return array An array of validators
+     * @param ?string $propertyName Name of the property to return validators for
+     * @return ($propertyName is null ? array<string,\SplObjectStorage<ValidatorInterface,mixed>> : \SplObjectStorage<ValidatorInterface,mixed>)
      */
-    public function getPropertyValidators($propertyName = null)
+    public function getPropertyValidators(?string $propertyName = null)
     {
         if ($propertyName !== null) {
-            return $this->propertyValidators[$propertyName] ?? [];
+            $propertyValidators = $this->propertyValidators[$propertyName] ?? null;
+            if (!$propertyValidators) {
+                /** @var \SplObjectStorage<ValidatorInterface,mixed> $propertyValidators */
+                $propertyValidators = new \SplObjectStorage();
+            }
+            return $propertyValidators;
         }
         return $this->propertyValidators;
     }
diff --git a/Neos.Flow/Classes/Validation/Validator/MediaTypeValidator.php b/Neos.Flow/Classes/Validation/Validator/MediaTypeValidator.php
index 5d0c7b3444..bc519d58c1 100644
--- a/Neos.Flow/Classes/Validation/Validator/MediaTypeValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/MediaTypeValidator.php
@@ -32,7 +32,7 @@ class MediaTypeValidator extends AbstractValidator
      * 2 => type
      * 3 => required (boolean, optional)
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'allowedTypes' => [[], 'Array of allowed media ranges', 'array', true],
diff --git a/Neos.Flow/Classes/Validation/Validator/NumberRangeValidator.php b/Neos.Flow/Classes/Validation/Validator/NumberRangeValidator.php
index ba6c31be92..07a1db9858 100644
--- a/Neos.Flow/Classes/Validation/Validator/NumberRangeValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/NumberRangeValidator.php
@@ -20,7 +20,7 @@
 class NumberRangeValidator extends AbstractValidator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'minimum' => [0, 'The minimum value to accept', 'integer'],
diff --git a/Neos.Flow/Classes/Validation/Validator/NumberValidator.php b/Neos.Flow/Classes/Validation/Validator/NumberValidator.php
index dd1a7db346..754a497cf9 100644
--- a/Neos.Flow/Classes/Validation/Validator/NumberValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/NumberValidator.php
@@ -23,7 +23,7 @@
 class NumberValidator extends AbstractValidator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'locale' => [null, 'The locale to use for number parsing', 'string|Locale'],
diff --git a/Neos.Flow/Classes/Validation/Validator/ObjectValidatorInterface.php b/Neos.Flow/Classes/Validation/Validator/ObjectValidatorInterface.php
index 43f27b1a29..e1c3fa30d8 100644
--- a/Neos.Flow/Classes/Validation/Validator/ObjectValidatorInterface.php
+++ b/Neos.Flow/Classes/Validation/Validator/ObjectValidatorInterface.php
@@ -21,7 +21,7 @@ interface ObjectValidatorInterface extends ValidatorInterface
     /**
      * Allows to set a container to keep track of validated instances.
      *
-     * @param \SplObjectStorage $validatedInstancesContainer A container to keep track of validated instances
+     * @param \SplObjectStorage<object, mixed> $validatedInstancesContainer A container to keep track of validated instances
      * @return void
      * @api
      */
diff --git a/Neos.Flow/Classes/Validation/Validator/RegularExpressionValidator.php b/Neos.Flow/Classes/Validation/Validator/RegularExpressionValidator.php
index b2e7ad387b..18cbf52301 100644
--- a/Neos.Flow/Classes/Validation/Validator/RegularExpressionValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/RegularExpressionValidator.php
@@ -21,7 +21,7 @@
 class RegularExpressionValidator extends AbstractValidator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'regularExpression' => ['', 'The regular expression to use for validation, used as given', 'string', true]
diff --git a/Neos.Flow/Classes/Validation/Validator/StringLengthValidator.php b/Neos.Flow/Classes/Validation/Validator/StringLengthValidator.php
index a48ecd7f19..e99f359400 100644
--- a/Neos.Flow/Classes/Validation/Validator/StringLengthValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/StringLengthValidator.php
@@ -22,7 +22,7 @@
 class StringLengthValidator extends AbstractValidator
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'minimum' => [0, 'Minimum length for a valid string', 'integer'],
diff --git a/Neos.Flow/Classes/Validation/Validator/UniqueEntityValidator.php b/Neos.Flow/Classes/Validation/Validator/UniqueEntityValidator.php
index 83fcb69dd2..8fba7bf2f7 100644
--- a/Neos.Flow/Classes/Validation/Validator/UniqueEntityValidator.php
+++ b/Neos.Flow/Classes/Validation/Validator/UniqueEntityValidator.php
@@ -16,7 +16,6 @@
 use Neos\Flow\Reflection\ClassSchema;
 use Neos\Utility\ObjectAccess;
 use Neos\Flow\Reflection\ReflectionService;
-use Neos\Utility\TypeHandling;
 use Neos\Flow\Validation\Exception\InvalidValidationOptionsException;
 
 /**
@@ -39,7 +38,7 @@ class UniqueEntityValidator extends AbstractValidator
     protected $persistenceManager;
 
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'identityProperties' => [null, 'List of custom identity properties.', 'array']
@@ -60,7 +59,7 @@ protected function isValid($value)
             throw new InvalidValidationOptionsException('The value supplied for the UniqueEntityValidator must be an object.', 1358454270);
         }
 
-        $classSchema = $this->reflectionService->getClassSchema(TypeHandling::getTypeForValue($value));
+        $classSchema = $this->reflectionService->getClassSchema($value);
         if ($classSchema === null || $classSchema->getModelType() !== ClassSchema::MODELTYPE_ENTITY) {
             throw new InvalidValidationOptionsException('The object supplied for the UniqueEntityValidator must be an entity.', 1358454284);
         }
diff --git a/Neos.Flow/Classes/Validation/Validator/ValidatorInterface.php b/Neos.Flow/Classes/Validation/Validator/ValidatorInterface.php
index b142149381..55cd6c4228 100644
--- a/Neos.Flow/Classes/Validation/Validator/ValidatorInterface.php
+++ b/Neos.Flow/Classes/Validation/Validator/ValidatorInterface.php
@@ -41,7 +41,7 @@ public function validate($value);
     /**
      * Returns the options of this validator which can be specified in the constructor
      *
-     * @return array
+     * @return array<mixed>
      */
     public function getOptions();
 }
diff --git a/Neos.Flow/Classes/Validation/ValidatorResolver.php b/Neos.Flow/Classes/Validation/ValidatorResolver.php
index 3400c85715..11a72dffae 100644
--- a/Neos.Flow/Classes/Validation/ValidatorResolver.php
+++ b/Neos.Flow/Classes/Validation/ValidatorResolver.php
@@ -77,7 +77,7 @@ class ValidatorResolver
     protected $reflectionService;
 
     /**
-     * @var array
+     * @var array<string,ConjunctionValidator>
      */
     protected $baseValidatorConjunctions = [];
 
@@ -87,7 +87,7 @@ class ValidatorResolver
      * could be resolved.
      *
      * @param string $validatorType Either one of the built-in data types or fully qualified validator class name
-     * @param array $validatorOptions Options to be passed to the validator
+     * @param array<mixed> $validatorOptions Options to be passed to the validator
      * @return ValidatorInterface|null
      * @throws Exception\NoSuchValidatorException
      * @throws Exception\InvalidValidationConfigurationException
@@ -114,10 +114,6 @@ public function createValidator($validatorType, array $validatorOptions = [])
                 throw new Exception\NoSuchValidatorException('The validator "' . $validatorObjectName . '" is not of scope singleton or prototype!', 1300694835);
         }
 
-        if (!($validator instanceof ValidatorInterface)) {
-            throw new Exception\NoSuchValidatorException(sprintf('The validator "%s" does not implement %s!', $validatorObjectName, ValidatorInterface::class), 1300694875);
-        }
-
         return $validator;
     }
 
@@ -127,7 +123,7 @@ public function createValidator($validatorType, array $validatorOptions = [])
      * If no validation is necessary, the returned validator is empty.
      *
      * @param string $targetClassName Fully qualified class name of the target class, ie. the class which should be validated
-     * @param array $validationGroups The validation groups to build the validator for
+     * @param array<int,string> $validationGroups The validation groups to build the validator for
      * @return ConjunctionValidator The validator conjunction
      * @throws Exception\InvalidValidationConfigurationException
      * @throws Exception\InvalidValidationOptionsException
@@ -150,10 +146,10 @@ public function getBaseValidatorConjunction($targetClassName, array $validationG
      * - by the data type specified in the param annotations
      * - additional validators specified in the validate annotations of a method
      *
-     * @param string $className
+     * @param class-string $className
      * @param string $methodName
-     * @param array $methodParameters Optional pre-compiled array of method parameters
-     * @param array $methodValidateAnnotations Optional pre-compiled array of validate annotations (as array)
+     * @param array<string,mixed>|null $methodParameters Optional pre-compiled array of method parameters
+     * @param array<array{type: ?string, options: array<mixed>, argumentName: string}>|null $methodValidateAnnotations Optional pre-compiled array of validate annotations (as array)
      * @return array<ConjunctionValidator> An Array of ValidatorConjunctions for each method parameters.
      * @throws Exception\InvalidValidationConfigurationException
      * @throws Exception\NoSuchValidatorException
@@ -202,7 +198,11 @@ public function buildMethodArgumentsValidatorConjunctions($className, $methodNam
         }
 
         foreach ($methodValidateAnnotations as $annotationParameters) {
-            $newValidator = $this->createValidator($annotationParameters['type'], $annotationParameters['options']);
+            $validatorType = $annotationParameters['type'] ?? null;
+            if ($validatorType === null) {
+                throw new \Exception('Missing validator type', 1743872674);
+            }
+            $newValidator = $this->createValidator($validatorType, $annotationParameters['options']);
             if ($newValidator === null) {
                 throw new Exception\NoSuchValidatorException('Invalid validate annotation in ' . $className . '->' . $methodName . '(): Could not resolve class name for  validator "' . $annotationParameters['type'] . '".', 1239853109);
             }
@@ -235,7 +235,7 @@ public function reset()
      * Builds a chain of nested object validators by specification of the given
      * object path.
      *
-     * @param array $objectPath The object path
+     * @param array<string> $objectPath The object path
      * @param ValidatorInterface $propertyValidator The validator which should be added to the property specified by objectPath
      * @return GenericObjectValidator
      * @throws Exception\InvalidValidationOptionsException
@@ -252,7 +252,12 @@ protected function buildSubObjectValidator(array $objectPath, ValidatorInterface
             $parentObjectValidator = $subObjectValidator;
         }
 
-        $parentObjectValidator->addPropertyValidator(array_shift($objectPath), $propertyValidator);
+        $propertyName = array_shift($objectPath);
+        if (!is_string($propertyName)) {
+            throw new \Exception('Missing propertyName', 1743872593);
+        }
+
+        $parentObjectValidator->addPropertyValidator($propertyName, $propertyValidator);
 
         return $rootObjectValidator;
     }
@@ -275,7 +280,7 @@ protected function buildSubObjectValidator(array $objectPath, ValidatorInterface
      *
      * @param string $indexKey The key to use as index in $this->baseValidatorConjunctions; calculated from target class name and validation groups
      * @param string $targetClassName The data type to build the validation conjunction for. Needs to be the fully qualified class name.
-     * @param array $validationGroups The validation groups to build the validator for
+     * @param array<int,string> $validationGroups The validation groups to build the validator for
      * @return void
      * @throws Exception\NoSuchValidatorException
      * @throws \InvalidArgumentException
@@ -333,6 +338,9 @@ protected function buildBaseValidatorConjunction($indexKey, $targetClassName, ar
 
                 $validateAnnotations = $this->reflectionService->getPropertyAnnotations($targetClassName, $classPropertyName, Flow\Validate::class);
                 foreach ($validateAnnotations as $validateAnnotation) {
+                    if ($validateAnnotation->type === null) {
+                        continue;
+                    }
                     if ($validateAnnotation->type === 'Collection') {
                         $needsCollectionValidator = false;
                         $validateAnnotation->options = array_merge(['elementType' => $parsedType['elementType'], 'validationGroups' => $validationGroups], $validateAnnotation->options);
@@ -356,7 +364,9 @@ protected function buildBaseValidatorConjunction($indexKey, $targetClassName, ar
 
                 if ($needsCollectionValidator) {
                     $collectionValidator = $this->createValidator(Validator\CollectionValidator::class, ['elementType' => $parsedType['elementType'], 'validationGroups' => $validationGroups]);
-                    $objectValidator->addPropertyValidator($classPropertyName, $collectionValidator);
+                    if ($collectionValidator instanceof ValidatorInterface) {
+                        $objectValidator->addPropertyValidator($classPropertyName, $collectionValidator);
+                    }
                 }
                 if ($needsObjectValidator) {
                     $validatorForProperty = $this->getBaseValidatorConjunction($propertyTargetClassName, $validationGroups);
@@ -424,7 +434,7 @@ protected function addCustomValidators($targetClassName, ConjunctionValidator &$
      * Returns a map of object validator class names.
      *
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of object validator class names
+     * @return list<class-string<PolyTypeObjectValidatorInterface>> Array of object validator class names
      * @Flow\CompileStatic
      */
     public static function getPolyTypeObjectValidatorImplementationClassNames($objectManager)
@@ -439,7 +449,7 @@ public static function getPolyTypeObjectValidatorImplementationClassNames($objec
      * validator is available false is returned
      *
      * @param string $validatorType Either the fully qualified class name of the validator or the short name of a built-in validator
-     * @return string|false Class name of the validator or false if not available
+     * @return class-string<ValidatorInterface>|false Class name of the validator or false if not available
      */
     protected function resolveValidatorObjectName($validatorType)
     {
@@ -448,6 +458,7 @@ protected function resolveValidatorObjectName($validatorType)
         $validatorClassNames = static::getValidatorImplementationClassNames($this->objectManager);
 
         if ($this->objectManager->isRegistered($validatorType) && isset($validatorClassNames[$validatorType])) {
+            /** @var class-string<ValidatorInterface> $validatorType */
             return $validatorType;
         }
 
@@ -458,6 +469,7 @@ protected function resolveValidatorObjectName($validatorType)
             $possibleClassName = sprintf('Neos\Flow\Validation\Validator\%sValidator', $this->getValidatorType($validatorType));
         }
         if ($this->objectManager->isRegistered($possibleClassName) && isset($validatorClassNames[$possibleClassName])) {
+            /** @var class-string<ValidatorInterface> $possibleClassName */
             return $possibleClassName;
         }
 
@@ -468,7 +480,7 @@ protected function resolveValidatorObjectName($validatorType)
      * Returns all class names implementing the ValidatorInterface.
      *
      * @param ObjectManagerInterface $objectManager
-     * @return array Array of class names implementing ValidatorInterface indexed by class name
+     * @return array<class-string<ValidatorInterface>,int> Array of class names implementing ValidatorInterface indexed by class name
      * @Flow\CompileStatic
      */
     public static function getValidatorImplementationClassNames($objectManager)
diff --git a/Neos.Flow/Tests/Unit/Core/Booting/ScriptsTest.php b/Neos.Flow/Tests/Unit/Core/Booting/ScriptsTest.php
index 3088f3fe4a..d3daf2e79a 100644
--- a/Neos.Flow/Tests/Unit/Core/Booting/ScriptsTest.php
+++ b/Neos.Flow/Tests/Unit/Core/Booting/ScriptsTest.php
@@ -27,11 +27,11 @@
  */
 class ScriptsMock extends Scripts
 {
-    protected static function ensureCLISubrequestsUseCurrentlyRunningPhpBinary($phpBinaryPathAndFilename)
+    protected static function ensureCLISubrequestsUseCurrentlyRunningPhpBinary($phpBinaryPathAndFilename): void
     {
     }
 
-    protected static function ensureWebSubrequestsUseCurrentlyRunningPhpVersion($phpCommand)
+    protected static function ensureWebSubrequestsUseCurrentlyRunningPhpVersion($phpCommand): void
     {
     }
 
diff --git a/Neos.Flow/Tests/Unit/ObjectManagement/Configuration/ConfigurationTest.php b/Neos.Flow/Tests/Unit/ObjectManagement/Configuration/ConfigurationTest.php
index d7909b649a..bfb74849cd 100644
--- a/Neos.Flow/Tests/Unit/ObjectManagement/Configuration/ConfigurationTest.php
+++ b/Neos.Flow/Tests/Unit/ObjectManagement/Configuration/ConfigurationTest.php
@@ -119,10 +119,10 @@ public function setFactoryMethodNameAcceptsValidStrings()
     /**
      * @test
      */
-    public function setFactoryMethodNameRejectsAnythingElseThanAString()
+    public function setFactoryMethodNameRejectsEmptyString()
     {
         $this->expectException(\InvalidArgumentException::class);
-        $this->objectConfiguration->setFactoryMethodName([]);
+        $this->objectConfiguration->setFactoryMethodName('');
     }
 
     /**
diff --git a/Neos.FluidAdaptor/Classes/Core/Cache/CacheAdaptor.php b/Neos.FluidAdaptor/Classes/Core/Cache/CacheAdaptor.php
index 43bb16e5a4..a80d47190b 100644
--- a/Neos.FluidAdaptor/Classes/Core/Cache/CacheAdaptor.php
+++ b/Neos.FluidAdaptor/Classes/Core/Cache/CacheAdaptor.php
@@ -50,7 +50,7 @@ public function get($name)
      * @param string $name
      * @param string $value
      */
-    public function set($name, $value)
+    public function set($name, $value): void
     {
         // we need to strip the first line with the php header as the flow cache adds that again.
         $this->flowCache->set($name, substr($value, strpos($value, "\n") + 1));
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/Interceptor/ResourceInterceptor.php b/Neos.FluidAdaptor/Classes/Core/Parser/Interceptor/ResourceInterceptor.php
index 286870a6ac..9334df24ad 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/Interceptor/ResourceInterceptor.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/Interceptor/ResourceInterceptor.php
@@ -97,7 +97,7 @@ public function process(NodeInterface $node, $interceptorPosition, ParsingState
         if (strpos($node->getText(), 'Public/') === false) {
             return $node;
         }
-        $textParts = preg_split(self::PATTERN_SPLIT_AT_RESOURCE_URIS, $node->getText(), -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
+        $textParts = preg_split(self::PATTERN_SPLIT_AT_RESOURCE_URIS, $node->getText(), -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE) ?: [];
         $node = new RootNode();
         foreach ($textParts as $part) {
             $matches = [];
@@ -109,7 +109,7 @@ public function process(NodeInterface $node, $interceptorPosition, ParsingState
                 if ($this->defaultPackageKey !== null) {
                     $arguments['package'] = new TextNode($this->defaultPackageKey);
                 }
-                if (isset($matches['Package']) && FlowPackageKey::isPackageKeyValid($matches['Package'])) {
+                if (FlowPackageKey::isPackageKeyValid($matches['Package'])) {
                     $arguments['package'] = new TextNode($matches['Package']);
                 }
 
@@ -127,7 +127,7 @@ public function process(NodeInterface $node, $interceptorPosition, ParsingState
     /**
      * This interceptor wants to hook into text nodes.
      *
-     * @return array Array of INTERCEPT_* constants
+     * @return array<int,int> Array of INTERCEPT_* constants
      */
     public function getInterceptionPoints()
     {
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/Expression/LegacyNamespaceExpressionNode.php b/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/Expression/LegacyNamespaceExpressionNode.php
index 1af2886355..cd63f4f625 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/Expression/LegacyNamespaceExpressionNode.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/Expression/LegacyNamespaceExpressionNode.php
@@ -24,14 +24,14 @@ class LegacyNamespaceExpressionNode extends AbstractExpressionNode implements Ex
      * Pattern which detects namespace declarations made inline.
      * syntax, e.g. {namespace neos=TYPO3\Neos\ViewHelpers}.
      */
-    public static $detectionExpression = '/{namespace\\s*([a-z0-9]+)\\s*=\\s*([a-z0-9_\\\\]+)\\s*}/i';
+    public static string $detectionExpression = '/{namespace\\s*([a-z0-9]+)\\s*=\\s*([a-z0-9_\\\\]+)\\s*}/i';
 
     /**
      * Evaluates the expression stored in this node, in the context of $renderingcontext.
      *
      * @param RenderingContextInterface $renderingContext
      * @param string $expression
-     * @param array $matches
+     * @param array<int,mixed> $matches
      * @return mixed
      */
     public static function evaluateExpression(RenderingContextInterface $renderingContext, $expression, array $matches)
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/ResourceUriNode.php b/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/ResourceUriNode.php
index db44103330..81301ef0d4 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/ResourceUriNode.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/SyntaxTree/ResourceUriNode.php
@@ -35,18 +35,17 @@ class ResourceUriNode extends ViewHelperNode
     protected $viewHelperResolver;
 
     /**
-     * @var string
+     * @var class-string<ResourceViewHelper>
      */
     protected $viewHelperClassName = ResourceViewHelper::class;
 
     /**
      * @param ViewHelperResolver $viewHelperResolver
      */
-    public function injectViewHelperResolver(ViewHelperResolver $viewHelperResolver)
+    public function injectViewHelperResolver(ViewHelperResolver $viewHelperResolver): void
     {
         $this->viewHelperResolver = $viewHelperResolver;
         $this->uninitializedViewHelper = $this->viewHelperResolver->createViewHelperInstanceFromClassName($this->viewHelperClassName);
-        /** @phpstan-ignore-next-line we use internal api */
         $this->uninitializedViewHelper->setViewHelperNode($this);
         $this->argumentDefinitions = $this->viewHelperResolver->getArgumentDefinitionsForViewHelper($this->uninitializedViewHelper);
     }
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateParser.php b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateParser.php
index 1ad1054885..db67139b41 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateParser.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateParser.php
@@ -17,7 +17,7 @@ public function isEscapingEnabled()
     /**
      * @param boolean $escapingEnabled
      */
-    public function setEscapingEnabled($escapingEnabled)
+    public function setEscapingEnabled($escapingEnabled): void
     {
         $this->escapingEnabled = $escapingEnabled;
     }
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/EscapingFlagProcessor.php b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/EscapingFlagProcessor.php
index fbdc9a72a1..1b61da951e 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/EscapingFlagProcessor.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/EscapingFlagProcessor.php
@@ -25,12 +25,12 @@ class EscapingFlagProcessor implements TemplateProcessorInterface
      */
     protected $renderingContext;
 
-    public static $SCAN_PATTERN_ESCAPINGMODIFIER = '/{escapingEnabled\s*=\s*(?P<enabled>true|false)\s*}/i';
+    public static string $SCAN_PATTERN_ESCAPINGMODIFIER = '/{escapingEnabled\s*=\s*(?P<enabled>true|false)\s*}/i';
 
     /**
      * @param RenderingContextInterface $renderingContext
      */
-    public function setRenderingContext(RenderingContextInterface $renderingContext)
+    public function setRenderingContext(RenderingContextInterface $renderingContext): void
     {
         $this->renderingContext = $renderingContext;
     }
@@ -56,7 +56,7 @@ public function preProcessSource($templateSource)
         if (strtolower($matches[0]['enabled']) === 'false') {
             $this->renderingContext->getTemplateParser()->setEscapingEnabled(false);
         }
-        $templateSource = preg_replace(self::$SCAN_PATTERN_ESCAPINGMODIFIER, '', $templateSource);
+        $templateSource = preg_replace(self::$SCAN_PATTERN_ESCAPINGMODIFIER, '', $templateSource) ?: '';
 
         return $templateSource;
     }
diff --git a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/NamespaceDetectionTemplateProcessor.php b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/NamespaceDetectionTemplateProcessor.php
index b6c18f2664..3c813c0c01 100644
--- a/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/NamespaceDetectionTemplateProcessor.php
+++ b/Neos.FluidAdaptor/Classes/Core/Parser/TemplateProcessor/NamespaceDetectionTemplateProcessor.php
@@ -29,7 +29,7 @@ class NamespaceDetectionTemplateProcessor extends FluidNamespaceDetectionTemplat
     /**
      * Extension of the default pattern for dynamic tags including namespaces with uppercase letters.
      */
-    public static $EXTENDED_SPLIT_PATTERN_TEMPLATE_DYNAMICTAGS = '/
+    public static string $EXTENDED_SPLIT_PATTERN_TEMPLATE_DYNAMICTAGS = '/
 		(
 			(?: <\/?                                      # Start dynamic tags
 					(?:(?:[a-zA-Z0-9\\.]*):[a-zA-Z0-9\\.]+)  # A tag consists of the namespace prefix and word characters
@@ -75,7 +75,7 @@ public function preProcessSource($templateSource)
      */
     public function protectCDataSectionsFromParser(string $templateSource)
     {
-        $parts = preg_split('/(\<\!\[CDATA\[|\]\]\>)/', $templateSource, -1, PREG_SPLIT_DELIM_CAPTURE);
+        $parts = preg_split('/(\<\!\[CDATA\[|\]\]\>)/', $templateSource, -1, PREG_SPLIT_DELIM_CAPTURE) ?: [];
         $balance = 0;
         $content = '';
         $resultingParts = [];
@@ -127,7 +127,7 @@ public function protectCDataSectionsFromParser(string $templateSource)
     public function throwExceptionsForUnhandledNamespaces(string $templateSource): void
     {
         $viewHelperResolver = $this->renderingContext->getViewHelperResolver();
-        $splitTemplate = preg_split(static::$EXTENDED_SPLIT_PATTERN_TEMPLATE_DYNAMICTAGS, $templateSource, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
+        $splitTemplate = preg_split(static::$EXTENDED_SPLIT_PATTERN_TEMPLATE_DYNAMICTAGS, $templateSource, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY) ?: [];
         foreach ($splitTemplate as $templateElement) {
             if (preg_match(Patterns::$SCAN_PATTERN_TEMPLATE_VIEWHELPERTAG, $templateElement, $matchedVariables) > 0) {
                 if (!$viewHelperResolver->isNamespaceValidOrIgnored($matchedVariables['NamespaceIdentifier'])) {
@@ -148,11 +148,9 @@ public function throwExceptionsForUnhandledNamespaces(string $templateSource): v
             foreach ($sections as $section) {
                 if (preg_match(Patterns::$SCAN_PATTERN_SHORTHANDSYNTAX_OBJECTACCESSORS, $section, $matchedVariables) > 0) {
                     preg_match_all(Patterns::$SPLIT_PATTERN_SHORTHANDSYNTAX_VIEWHELPER, $section, $shorthandViewHelpers, PREG_SET_ORDER);
-                    if (is_array($shorthandViewHelpers) === true) {
-                        foreach ($shorthandViewHelpers as $shorthandViewHelper) {
-                            if (!$viewHelperResolver->isNamespaceValidOrIgnored($shorthandViewHelper['NamespaceIdentifier'])) {
-                                throw new UnknownNamespaceException('Unknown Namespace: ' . $shorthandViewHelper['NamespaceIdentifier']);
-                            }
+                    foreach ($shorthandViewHelpers as $shorthandViewHelper) {
+                        if (!$viewHelperResolver->isNamespaceValidOrIgnored($shorthandViewHelper['NamespaceIdentifier'])) {
+                            throw new UnknownNamespaceException('Unknown Namespace: ' . $shorthandViewHelper['NamespaceIdentifier']);
                         }
                     }
                 }
diff --git a/Neos.FluidAdaptor/Classes/Core/Rendering/RenderingContext.php b/Neos.FluidAdaptor/Classes/Core/Rendering/RenderingContext.php
index 3c68fb552b..8869960689 100644
--- a/Neos.FluidAdaptor/Classes/Core/Rendering/RenderingContext.php
+++ b/Neos.FluidAdaptor/Classes/Core/Rendering/RenderingContext.php
@@ -15,7 +15,6 @@
 use Neos\FluidAdaptor\Core\Parser\TemplateParser;
 use Neos\FluidAdaptor\Core\Parser\TemplateProcessor\EscapingFlagProcessor;
 use Neos\Flow\Annotations as Flow;
-use Neos\Flow\Mvc\ActionRequest;
 use Neos\Flow\Mvc\Controller\ControllerContext;
 use Neos\Flow\ObjectManagement\ObjectManagerInterface;
 use Neos\FluidAdaptor\Core\Parser\Interceptor\ResourceInterceptor;
@@ -25,6 +24,7 @@
 use Neos\FluidAdaptor\Core\ViewHelper\ViewHelperResolver;
 use Neos\FluidAdaptor\View\TemplatePaths;
 use TYPO3Fluid\Fluid\Core\Parser\Configuration;
+use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\Expression\AbstractExpressionNode;
 use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\Expression\CastingExpressionNode;
 use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\Expression\MathExpressionNode;
 use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\Expression\TernaryExpressionNode;
@@ -42,7 +42,7 @@ class RenderingContext extends FluidRenderingContext implements FlowAwareRenderi
      * which will be consulted when an expression does not match
      * any built-in parser expression types.
      *
-     * @var array
+     * @var array<class-string<AbstractExpressionNode>>
      */
     protected $expressionNodeTypes = [
         LegacyNamespaceExpressionNode::class,
@@ -81,7 +81,7 @@ class RenderingContext extends FluidRenderingContext implements FlowAwareRenderi
     /**
      * RenderingContext constructor.
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      */
     public function __construct(array $options = [])
     {
@@ -100,7 +100,7 @@ public function __construct(array $options = [])
     /**
      * @param ObjectManagerInterface $objectManager
      */
-    public function injectObjectManager(ObjectManagerInterface $objectManager)
+    public function injectObjectManager(ObjectManagerInterface $objectManager): void
     {
         $this->objectManager = $objectManager;
     }
@@ -116,11 +116,11 @@ public function getControllerContext()
     /**
      * @param ControllerContext $controllerContext
      */
-    public function setControllerContext($controllerContext)
+    public function setControllerContext($controllerContext): void
     {
         $this->controllerContext = $controllerContext;
         $request = $controllerContext->getRequest();
-        if (!$this->templatePaths instanceof TemplatePaths || !$request instanceof ActionRequest) {
+        if (!$this->templatePaths instanceof TemplatePaths) {
             return;
         }
 
diff --git a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractConditionViewHelper.php b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractConditionViewHelper.php
index 052ef09e98..60c8b848f9 100644
--- a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractConditionViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractConditionViewHelper.php
@@ -46,7 +46,7 @@ abstract class AbstractConditionViewHelper extends AbstractViewHelper
     /**
      * Initializes the "then" and "else" arguments
      */
-    public function initializeArguments()
+    public function initializeArguments(): void
     {
         $this->registerArgument('then', 'mixed', 'Value to be returned if the condition if met.', false);
         $this->registerArgument('else', 'mixed', 'Value to be returned if the condition if not met.', false);
@@ -66,18 +66,19 @@ public function initializeArguments()
      * subclasses that will be using this base class in the future. Let this
      * be a warning if someone considers changing this method signature!
      *
-     * @param array|NULL $arguments
+     * @param array<mixed>|NULL $arguments
      * @param RenderingContextInterface $renderingContext
      * @return boolean
      * @api
      */
     protected static function evaluateCondition($arguments, RenderingContextInterface $renderingContext)
     {
-        return (boolean)$arguments['condition'];
+        // fallback value derived from registerArgument default value
+        return (boolean)($arguments['condition'] ?? false);
     }
 
     /**
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return mixed
@@ -103,8 +104,8 @@ public static function renderStatic(array $arguments, \Closure $renderChildrenCl
     }
 
     /**
-     * @param array $closures
-     * @param array $conditionClosures
+     * @param array<mixed> $closures
+     * @param array<mixed> $conditionClosures
      * @param RenderingContextInterface $renderingContext
      * @return string
      */
@@ -236,7 +237,7 @@ public function compile($argumentsName, $closureName, &$initializationPhpCode, V
 
     /**
      * @param boolean $isConditionFullfilled
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param RenderingContextInterface $renderingContext
      * @return mixed
      */
diff --git a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractLocaleAwareViewHelper.php b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractLocaleAwareViewHelper.php
index 5f33d1e651..436817dfea 100644
--- a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractLocaleAwareViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractLocaleAwareViewHelper.php
@@ -39,7 +39,7 @@ public function __construct()
     /**
      * @param I18n\Service $localizationService
      */
-    public function injectLocalizationService(I18n\Service $localizationService)
+    public function injectLocalizationService(I18n\Service $localizationService): void
     {
         $this->localizationService = $localizationService;
     }
diff --git a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractTagBasedViewHelper.php b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractTagBasedViewHelper.php
index d4743808a6..2ce96b048d 100644
--- a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractTagBasedViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractTagBasedViewHelper.php
@@ -32,7 +32,7 @@ abstract class AbstractTagBasedViewHelper extends AbstractViewHelper
     /**
      * Names of all registered tag attributes
      *
-     * @var array
+     * @var array<mixed>
      */
     private static $tagAttributes = [];
 
@@ -156,7 +156,7 @@ protected function registerUniversalTagAttributes()
      * which in the default implementation will throw an error
      * about "undeclared argument used".
      *
-     * @param array $arguments
+     * @param array<string,string|\Traversable<mixed>|array<mixed>|null> $arguments
      * @return void
      */
     public function handleAdditionalArguments(array $arguments)
diff --git a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractViewHelper.php b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractViewHelper.php
index 6731a63562..e80a9b38de 100644
--- a/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/Core/ViewHelper/AbstractViewHelper.php
@@ -59,9 +59,7 @@ public function setRenderingContext(RenderingContextInterface $renderingContext)
         $this->renderingContext = $renderingContext;
         $this->templateVariableContainer = $renderingContext->getVariableProvider();
         $this->viewHelperVariableContainer = $renderingContext->getViewHelperVariableContainer();
-        if ($renderingContext instanceof FlowAwareRenderingContextInterface) {
-            $this->controllerContext = $renderingContext->getControllerContext();
-        }
+        $this->controllerContext = $renderingContext->getControllerContext();
     }
 
     /**
diff --git a/Neos.FluidAdaptor/Classes/Core/ViewHelper/ViewHelperResolver.php b/Neos.FluidAdaptor/Classes/Core/ViewHelper/ViewHelperResolver.php
index 8351bfa4f1..9282263018 100644
--- a/Neos.FluidAdaptor/Classes/Core/ViewHelper/ViewHelperResolver.php
+++ b/Neos.FluidAdaptor/Classes/Core/ViewHelper/ViewHelperResolver.php
@@ -15,6 +15,7 @@
 use Neos\Flow\ObjectManagement\ObjectManagerInterface;
 use Neos\Flow\Package\Package;
 use Neos\Flow\Package\PackageManager;
+use TYPO3Fluid\Fluid\Core\ViewHelper\ViewHelperInterface;
 
 /**
  * Class ViewHelperResolver
@@ -49,17 +50,17 @@ class ViewHelperResolver extends \TYPO3Fluid\Fluid\Core\ViewHelper\ViewHelperRes
      * will look for classes in both namespaces starting
      * from the bottom.
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $namespaces = [];
 
     /**
      * @Flow\InjectConfiguration(path="namespaces")
-     * @var array
+     * @var array<mixed>
      */
     protected $namespacesFromConfiguration;
 
-    public function initializeObject($reason)
+    public function initializeObject(int $reason): void
     {
         if ($reason === ObjectManagerInterface::INITIALIZATIONCAUSE_RECREATED) {
             return;
@@ -83,8 +84,9 @@ public function initializeObject($reason)
     }
 
     /**
-     * @param string $viewHelperClassName
-     * @return \TYPO3Fluid\Fluid\Core\ViewHelper\ViewHelperInterface
+     * @template T of ViewHelperInterface
+     * @param class-string<T> $viewHelperClassName
+     * @return T
      */
     public function createViewHelperInstanceFromClassName($viewHelperClassName)
     {
@@ -125,7 +127,7 @@ public function createViewHelperInstanceFromClassName($viewHelperClassName)
      * when you use this method you should always include the "f" namespace.
      *
      * @param string $identifier
-     * @param string|array $phpNamespace
+     * @param string|array<string>|null $phpNamespace
      * @return void
      */
     public function addNamespace($identifier, $phpNamespace)
@@ -149,7 +151,7 @@ public function addNamespace($identifier, $phpNamespace)
      * @param string $identifier
      * @param string $phpNamespace
      */
-    protected function addNamespaceInternal($identifier, $phpNamespace)
+    protected function addNamespaceInternal($identifier, $phpNamespace): void
     {
         if (!isset($this->namespaces[$identifier])) {
             $this->namespaces[$identifier] = [];
diff --git a/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetController.php b/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetController.php
index c7b38b4a80..4c07eab1e2 100644
--- a/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetController.php
+++ b/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetController.php
@@ -36,7 +36,7 @@ abstract class AbstractWidgetController extends ActionController
     /**
      * Configuration for this widget.
      *
-     * @var array
+     * @var array<mixed>
      * @api
      */
     protected $widgetConfiguration;
@@ -60,7 +60,6 @@ abstract class AbstractWidgetController extends ActionController
      */
     public function processRequest(ActionRequest $request): ResponseInterface
     {
-        /** @var WidgetContext $widgetContext */
         $widgetContext = $request->getInternalArgument('__widgetContext');
         if (!$widgetContext instanceof WidgetContext) {
             throw new WidgetContextNotFoundException('The widget context could not be found in the request.', 1307450180);
diff --git a/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetViewHelper.php b/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetViewHelper.php
index e390a32db6..db341c1186 100644
--- a/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/Core/Widget/AbstractWidgetViewHelper.php
@@ -20,6 +20,7 @@
 use Neos\FluidAdaptor\Core\ViewHelper\AbstractViewHelper;
 use Neos\FluidAdaptor\Core\ViewHelper\Facets\ChildNodeAccessInterface;
 use TYPO3Fluid\Fluid\Core\Compiler\TemplateCompiler;
+use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\NodeInterface;
 use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\RootNode;
 use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\ViewHelperNode;
 
@@ -38,7 +39,7 @@ abstract class AbstractWidgetViewHelper extends AbstractViewHelper implements Ch
      * This needs to be filled by the individual subclass using
      * property injection.
      *
-     * @var AbstractWidgetController
+     * @var AbstractWidgetController|DependencyProxy
      * @api
      */
     protected $controller;
@@ -150,7 +151,7 @@ private function initializeWidgetContext()
      * Stores the syntax tree child nodes in the Widget Context, so they can be
      * rendered with <f:widget.renderChildren> lateron.
      *
-     * @param array $childNodes The SyntaxTree Child nodes of this ViewHelper.
+     * @param array<NodeInterface> $childNodes The SyntaxTree Child nodes of this ViewHelper.
      * @return void
      */
     public function setChildNodes(array $childNodes)
@@ -166,7 +167,7 @@ public function setChildNodes(array $childNodes)
     /**
      * Generate the configuration for this widget. Override to adjust.
      *
-     * @return array
+     * @return array<mixed>
      * @api
      */
     protected function getWidgetConfiguration()
@@ -179,7 +180,7 @@ protected function getWidgetConfiguration()
      *
      * By default, returns getWidgetConfiguration(). Should become API later.
      *
-     * @return array
+     * @return array<mixed>
      */
     protected function getAjaxWidgetConfiguration()
     {
@@ -191,7 +192,7 @@ protected function getAjaxWidgetConfiguration()
      *
      * By default, returns getWidgetConfiguration(). Should become API later.
      *
-     * @return array
+     * @return array<mixed>
      */
     protected function getNonAjaxWidgetConfiguration()
     {
@@ -231,6 +232,9 @@ protected function initiateSubRequest()
             }
             $subRequest->setControllerObjectName($this->widgetContext->getControllerObjectName());
             try {
+                if (!($this->controller instanceof AbstractWidgetController)) {
+                    throw new Exception\MissingControllerException('initiateSubRequest() can not be called if there is no controller inside $this->controller. Make sure to add the @Neos\Flow\Annotations\Inject annotation in your widget class.', 1284401632);
+                }
                 $subResponse = $this->controller->processRequest($subRequest);
 
                 // We need to make sure to not merge content up into the parent ActionResponse because that _could_ break the parent response.
diff --git a/Neos.FluidAdaptor/Classes/Core/Widget/AjaxWidgetContextHolder.php b/Neos.FluidAdaptor/Classes/Core/Widget/AjaxWidgetContextHolder.php
index f78a163c2f..81a7077866 100644
--- a/Neos.FluidAdaptor/Classes/Core/Widget/AjaxWidgetContextHolder.php
+++ b/Neos.FluidAdaptor/Classes/Core/Widget/AjaxWidgetContextHolder.php
@@ -30,7 +30,7 @@ class AjaxWidgetContextHolder
      * An array $ajaxWidgetIdentifier => $widgetContext
      * which stores the widget context.
      *
-     * @var array
+     * @var array<string,WidgetContext>
      */
     protected $widgetContexts = [];
 
diff --git a/Neos.FluidAdaptor/Classes/Core/Widget/WidgetContext.php b/Neos.FluidAdaptor/Classes/Core/Widget/WidgetContext.php
index de1beed414..fb679f500f 100644
--- a/Neos.FluidAdaptor/Classes/Core/Widget/WidgetContext.php
+++ b/Neos.FluidAdaptor/Classes/Core/Widget/WidgetContext.php
@@ -48,7 +48,7 @@ class WidgetContext
      * controller as $this->widgetConfiguration, if being inside an AJAX
      * request
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $ajaxWidgetConfiguration;
 
@@ -57,7 +57,7 @@ class WidgetContext
      * controller as $this->widgetConfiguration, if being inside a non-AJAX
      * request
      *
-     * @var array
+     * @var array<mixed>
      */
     protected $nonAjaxWidgetConfiguration;
     /**
@@ -71,7 +71,7 @@ class WidgetContext
      * The child nodes of the Widget ViewHelper.
      * Only available inside non-AJAX requests.
      *
-     * @var RootNode
+     * @var ?RootNode
      * @Flow\Transient
      */
     protected $viewHelperChildNodes;
@@ -80,7 +80,7 @@ class WidgetContext
      * The rendering context of the ViewHelperChildNodes.
      * Only available inside non-AJAX requests.
      *
-     * @var RenderingContextInterface
+     * @var ?RenderingContextInterface
      * @Flow\Transient
      */
     protected $viewHelperChildNodeRenderingContext;
@@ -120,7 +120,7 @@ public function setAjaxWidgetIdentifier($ajaxWidgetIdentifier)
     }
 
     /**
-     * @return array
+     * @return array<mixed>
      */
     public function getWidgetConfiguration()
     {
@@ -132,7 +132,7 @@ public function getWidgetConfiguration()
     }
 
     /**
-     * @param array $ajaxWidgetConfiguration
+     * @param array<mixed> $ajaxWidgetConfiguration
      * @return void
      */
     public function setAjaxWidgetConfiguration(array $ajaxWidgetConfiguration)
@@ -141,7 +141,7 @@ public function setAjaxWidgetConfiguration(array $ajaxWidgetConfiguration)
     }
 
     /**
-     * @param array $nonAjaxWidgetConfiguration
+     * @param array<mixed> $nonAjaxWidgetConfiguration
      * @return void
      */
     public function setNonAjaxWidgetConfiguration(array $nonAjaxWidgetConfiguration)
@@ -178,17 +178,14 @@ public function setViewHelperChildNodes(RootNode $viewHelperChildNodes, Renderin
     }
 
     /**
-     * @return RootNode
+     * @return ?RootNode
      */
     public function getViewHelperChildNodes()
     {
         return $this->viewHelperChildNodes;
     }
 
-    /**
-     * @return RenderingContextInterface
-     */
-    public function getViewHelperChildNodeRenderingContext()
+    public function getViewHelperChildNodeRenderingContext(): ?RenderingContextInterface
     {
         return $this->viewHelperChildNodeRenderingContext;
     }
diff --git a/Neos.FluidAdaptor/Classes/Service/AbstractGenerator.php b/Neos.FluidAdaptor/Classes/Service/AbstractGenerator.php
index 0b37087aab..6001780143 100644
--- a/Neos.FluidAdaptor/Classes/Service/AbstractGenerator.php
+++ b/Neos.FluidAdaptor/Classes/Service/AbstractGenerator.php
@@ -54,7 +54,7 @@ public function __construct()
      * Get all class names inside this namespace and return them as array.
      *
      * @param string $namespace
-     * @return array Array of all class names inside a given namespace.
+     * @return array<int,class-string<AbstractViewHelper>> Array of all class names inside a given namespace.
      */
     protected function getClassNamesInNamespace($namespace)
     {
@@ -101,7 +101,7 @@ protected function getTagNameForClass($className, $namespace)
      * @param \SimpleXMLElement $parentXmlNode Parent XML Node to add the child to
      * @param string $childNodeName Name of the child node
      * @param string $childNodeValue Value of the child node. Will be placed inside CDATA.
-     * @return \SimpleXMLElement the new element
+     * @return ?\SimpleXMLElement the new element
      */
     protected function addChildWithCData(\SimpleXMLElement $parentXmlNode, $childNodeName, $childNodeValue)
     {
@@ -110,8 +110,12 @@ protected function addChildWithCData(\SimpleXMLElement $parentXmlNode, $childNod
 
         $childNode = $domDocument->appendChild($domDocument->createElement($childNodeName));
         $childNode->appendChild($domDocument->createCDATASection($childNodeValue));
-        $childNodeTarget = $parentDomNode->ownerDocument->importNode($childNode, true);
-        $parentDomNode->appendChild($childNodeTarget);
-        return simplexml_import_dom($childNodeTarget);
+        $childNodeTarget = $parentDomNode->ownerDocument?->importNode($childNode, true);
+        if ($childNodeTarget instanceof \DOMNode) {
+            $parentDomNode->appendChild($childNodeTarget);
+            return simplexml_import_dom($childNodeTarget);
+        }
+
+        return null;
     }
 }
diff --git a/Neos.FluidAdaptor/Classes/Service/XsdGenerator.php b/Neos.FluidAdaptor/Classes/Service/XsdGenerator.php
index c67220d2e9..be4fda8617 100644
--- a/Neos.FluidAdaptor/Classes/Service/XsdGenerator.php
+++ b/Neos.FluidAdaptor/Classes/Service/XsdGenerator.php
@@ -54,7 +54,11 @@ public function generateXsd($viewHelperNamespace, $xsdNamespace)
             $this->generateXmlForClassName($className, $viewHelperNamespace, $xmlRootNode);
         }
 
-        return $xmlRootNode->asXML();
+        $result = $xmlRootNode->asXML();
+
+        return is_string($result)
+            ? $result
+            : throw new \Exception('Failed to generate xsd', 1743851104);
     }
 
     /**
@@ -75,15 +79,22 @@ protected function generateXmlForClassName($className, $viewHelperNamespace, \Si
         $tagName = $this->getTagNameForClass($className, $viewHelperNamespace);
 
         $xsdElement = $xmlRootNode->addChild('xsd:element');
+        /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
         $xsdElement->offsetSet('name', $tagName);
-        $this->docCommentParser->parseDocComment($reflectionClass->getDocComment());
+        $docComment = $reflectionClass->getDocComment();
+        if ($docComment !== false) {
+            $this->docCommentParser->parseDocComment($docComment);
+        }
         $this->addDocumentation($this->docCommentParser->getDescription(), $xsdElement);
 
         $xsdComplexType = $xsdElement->addChild('xsd:complexType');
+        /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
         $xsdComplexType->offsetSet('mixed', 'true');
         $xsdSequence = $xsdComplexType->addChild('xsd:sequence');
         $xsdAny = $xsdSequence->addChild('xsd:any');
+        /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
         $xsdAny->offsetSet('minOccurs', '0');
+        /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
         $xsdAny->offsetSet('maxOccurs', 'unbounded');
 
         $this->addAttributes($className, $xsdComplexType);
@@ -106,10 +117,13 @@ protected function addAttributes($className, \SimpleXMLElement $xsdElement)
         foreach ($argumentDefinitions as $argumentDefinition) {
             /** @var \SimpleXMLElement $xsdAttribute */
             $xsdAttribute = $xsdElement->addChild('xsd:attribute');
+            /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
             $xsdAttribute->offsetSet('type', 'xsd:string');
+            /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
             $xsdAttribute->offsetSet('name', $argumentDefinition->getName());
             $this->addDocumentation($argumentDefinition->getDescription(), $xsdAttribute);
             if ($argumentDefinition->isRequired()) {
+                /** @phpstan-ignore argument.type (offsetSet accepts mixed) */
                 $xsdAttribute->offsetSet('use', 'required');
             }
         }
diff --git a/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php b/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php
index 37a64bfa17..a16e5366b3 100644
--- a/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php
+++ b/Neos.FluidAdaptor/Classes/View/AbstractTemplateView.php
@@ -12,7 +12,6 @@
  */
 
 use Neos\FluidAdaptor\Exception;
-use Neos\Flow\Mvc\ActionRequest;
 use Neos\Flow\Mvc\Controller\ControllerContext;
 use Neos\Flow\Mvc\View\ViewInterface;
 use Neos\FluidAdaptor\Core\Rendering\RenderingContext;
@@ -36,7 +35,7 @@ abstract class AbstractTemplateView extends \TYPO3Fluid\Fluid\View\AbstractTempl
      *         ...
      *     )
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected $supportedOptions = [
         'templateRootPathPattern' => [
@@ -101,7 +100,7 @@ abstract class AbstractTemplateView extends \TYPO3Fluid\Fluid\View\AbstractTempl
      *
      * @see $supportedOptions
      *
-     * @var array
+     * @var array<string,mixed>
      */
     protected $options = [];
 
@@ -124,6 +123,9 @@ public function assign($key, $value): self
         return parent::assign($key, $value);
     }
 
+    /**
+     * @param array<string,mixed> $values
+     */
     public function assignMultiple(array $values): self
     {
         // layer to fix incompatibility error with typo3 fluid interface
@@ -133,7 +135,7 @@ public function assignMultiple(array $values): self
     /**
      * Factory method to create an instance with given options.
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      * @return static
      */
     public static function createWithOptions(array $options): self
@@ -144,7 +146,7 @@ public static function createWithOptions(array $options): self
     /**
      * Set default options based on the supportedOptions provided
      *
-     * @param array $options
+     * @param array<string,mixed>|null $options
      * @throws Exception
      */
     public function __construct(?array $options = null)
@@ -184,14 +186,9 @@ public function setControllerContext(ControllerContext $controllerContext)
             $renderingContext->setControllerContext($controllerContext);
         }
 
-
         $paths = $this->getTemplatePaths();
         $request = $controllerContext->getRequest();
 
-        if (!$request instanceof ActionRequest) {
-            return;
-        }
-
         $paths->setFormat($request->getFormat());
 
         if ($paths->getTemplateRootPaths() === [] && $paths->getLayoutRootPaths() === [] && $paths->getPartialRootPaths() === []) {
@@ -205,7 +202,7 @@ public function setControllerContext(ControllerContext $controllerContext)
      * Renders a given section.
      *
      * @param string $sectionName Name of section to render
-     * @param array $variables The variables to use
+     * @param array<string,mixed> $variables The variables to use
      * @param boolean $ignoreUnknown Ignore an unknown section and just return an empty string
      * @return string rendered template for the section
      * @throws \Neos\FluidAdaptor\View\Exception\InvalidSectionException
@@ -217,13 +214,14 @@ public function renderSection($sectionName, array $variables = [], $ignoreUnknow
             $variables = $this->getRenderingContext()->getVariableProvider()->getAll();
         }
 
+        /** @phpstan-ignore argument.type (we assume Fluid actually supports \ArrayAccess here, too) */
         return parent::renderSection($sectionName, $variables, $ignoreUnknown);
     }
 
     /**
      * Validate options given to this view.
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      * @return void
      * @throws Exception
      */
@@ -250,10 +248,10 @@ function ($supportedOptionData, $supportedOptionName, $options) {
      * Merges the given options with the default values
      * and sets the resulting options in this object.
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      * @return void
      */
-    protected function setOptions(array $options)
+    protected function setOptions(array $options): void
     {
         $this->options = array_merge(
             array_map(
diff --git a/Neos.FluidAdaptor/Classes/View/StandaloneView.php b/Neos.FluidAdaptor/Classes/View/StandaloneView.php
index 6fdb79413a..d4a3cbfc6f 100644
--- a/Neos.FluidAdaptor/Classes/View/StandaloneView.php
+++ b/Neos.FluidAdaptor/Classes/View/StandaloneView.php
@@ -51,7 +51,7 @@ class StandaloneView extends AbstractTemplateView
     protected $environment;
 
     /**
-     * @var ActionRequest
+     * @var ?ActionRequest
      */
     protected $request;
 
@@ -64,7 +64,7 @@ class StandaloneView extends AbstractTemplateView
     /**
      * Factory method to create an instance with given options.
      *
-     * @param array $options
+     * @param array<string,mixed> $options
      * @return static
      */
     public static function createWithOptions(array $options): self
@@ -75,11 +75,12 @@ public static function createWithOptions(array $options): self
     /**
      * Constructor
      *
-     * @param ActionRequest $request The current action request. If none is specified it will be created from the environment.
-     * @param array $options
+     * @param ?ActionRequest $request The current action request. If none is specified it will be created from the environment.
+     * @param array<string,mixed>|null $options
      * @throws \Neos\FluidAdaptor\Exception
+     * @phpstan-ignore method.childParameterType (parameters are differently ordered and thus cannot match)
      */
-    public function __construct(?ActionRequest $request = null, array $options = [])
+    public function __construct(?ActionRequest $request = null, ?array $options = [])
     {
         $this->request = $request;
         parent::__construct($options);
@@ -116,7 +117,7 @@ public function initializeObject()
     /**
      * @param string $templateName
      */
-    public function setTemplate($templateName)
+    public function setTemplate($templateName): void
     {
         $this->baseRenderingContext->setControllerAction($templateName);
     }
@@ -130,6 +131,9 @@ public function setTemplate($templateName)
      */
     public function setFormat($format)
     {
+        if (!$this->request) {
+            throw new \Exception('Cannot set format without a request', 1743856310);
+        }
         $this->request->setFormat($format);
         $this->baseRenderingContext->getTemplatePaths()->setFormat($format);
     }
@@ -137,18 +141,18 @@ public function setFormat($format)
     /**
      * Returns the format of the current request (defaults is "html")
      *
-     * @return string $format
+     * @return ?string $format
      * @api
      */
     public function getFormat()
     {
-        return $this->request->getFormat();
+        return $this->request?->getFormat();
     }
 
     /**
      * Returns the current request object
      *
-     * @return ActionRequest
+     * @return ?ActionRequest
      */
     public function getRequest()
     {
@@ -177,12 +181,20 @@ public function setTemplatePathAndFilename($templatePathAndFilename)
     /**
      * Returns the absolute path to a Fluid template file if it was specified with setTemplatePathAndFilename() before
      *
-     * @return string Fluid template path
+     * @return ?string Fluid template path
      * @api
      */
     public function getTemplatePathAndFilename()
     {
-        return $this->baseRenderingContext->getTemplatePaths()->resolveTemplateFileForControllerAndActionAndFormat($this->request->getControllerName(), $this->request->getControllerActionName(), $this->request->getFormat());
+        return $this->request
+            ? $this->baseRenderingContext
+                ->getTemplatePaths()
+                ->resolveTemplateFileForControllerAndActionAndFormat(
+                    $this->request->getControllerName(),
+                    $this->request->getControllerActionName(),
+                    $this->request->getFormat()
+                )
+            : null;
     }
 
     /**
@@ -225,7 +237,7 @@ public function setLayoutRootPaths(array $layoutRootPaths)
     /**
      * Resolves the layout root to be used inside other paths.
      *
-     * @return array Fluid layout root paths
+     * @return array<string> Fluid layout root paths
      * @throws InvalidTemplateResourceException
      * @api
      */
@@ -262,7 +274,7 @@ public function setPartialRootPaths(array $partialRootPaths)
     /**
      * Returns the absolute path to the folder that contains Fluid partial files
      *
-     * @return array Fluid partial root paths
+     * @return array<string> Fluid partial root paths
      * @throws InvalidTemplateResourceException
      * @api
      */
diff --git a/Neos.FluidAdaptor/Classes/View/TemplatePaths.php b/Neos.FluidAdaptor/Classes/View/TemplatePaths.php
index ee45bae7eb..6c577db4ae 100644
--- a/Neos.FluidAdaptor/Classes/View/TemplatePaths.php
+++ b/Neos.FluidAdaptor/Classes/View/TemplatePaths.php
@@ -52,7 +52,7 @@ class TemplatePaths extends \TYPO3Fluid\Fluid\View\TemplatePaths
     ];
 
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $options = [];
 
@@ -61,6 +61,9 @@ class TemplatePaths extends \TYPO3Fluid\Fluid\View\TemplatePaths
      */
     protected $packageManager;
 
+    /**
+     * @param array<string,mixed> $options
+     */
     public function __construct(array $options = [])
     {
         foreach ($options as $optionName => $optionValue) {
@@ -71,7 +74,7 @@ public function __construct(array $options = [])
     /**
      * @param PackageManager $packageManager
      */
-    public function injectPackageManager(PackageManager $packageManager)
+    public function injectPackageManager(PackageManager $packageManager): void
     {
         $this->packageManager = $packageManager;
     }
@@ -87,7 +90,7 @@ public function getTemplateRootPathPattern(): string
     /**
      * @param string $templateRootPathPattern
      */
-    public function setTemplateRootPathPattern(string $templateRootPathPattern)
+    public function setTemplateRootPathPattern(string $templateRootPathPattern): void
     {
         $this->templateRootPathPattern = $templateRootPathPattern;
     }
@@ -95,7 +98,7 @@ public function setTemplateRootPathPattern(string $templateRootPathPattern)
     /**
      * @param string $layoutRootPathPattern
      */
-    public function setLayoutRootPathPattern(string $layoutRootPathPattern)
+    public function setLayoutRootPathPattern(string $layoutRootPathPattern): void
     {
         $this->layoutRootPathPattern = $layoutRootPathPattern;
     }
@@ -103,7 +106,7 @@ public function setLayoutRootPathPattern(string $layoutRootPathPattern)
     /**
      * @param string $partialRootPathPattern
      */
-    public function setPartialRootPathPattern(string $partialRootPathPattern)
+    public function setPartialRootPathPattern(string $partialRootPathPattern): void
     {
         $this->partialRootPathPattern = $partialRootPathPattern;
     }
@@ -111,7 +114,7 @@ public function setPartialRootPathPattern(string $partialRootPathPattern)
     /**
      * @param string $templateRootPath
      */
-    public function setTemplateRootPath($templateRootPath)
+    public function setTemplateRootPath($templateRootPath): void
     {
         $this->templateRootPaths = [$templateRootPath];
     }
@@ -119,7 +122,7 @@ public function setTemplateRootPath($templateRootPath)
     /**
      * Resolves the template root to be used inside other paths.
      *
-     * @return array Path(s) to template root directory
+     * @return array<string> Path(s) to template root directory
      */
     public function getTemplateRootPaths()
     {
@@ -140,7 +143,7 @@ public function getTemplateRootPaths()
     }
 
     /**
-     * @return array
+     * @return array<string>
      */
     public function getLayoutRootPaths()
     {
@@ -160,7 +163,10 @@ public function getLayoutRootPaths()
         return [$layoutRootPath];
     }
 
-    public function getPartialRootPaths()
+    /**
+     * @return array<string>
+     */
+    public function getPartialRootPaths(): array
     {
         if ($this->partialRootPaths !== []) {
             return $this->partialRootPaths;
@@ -181,7 +187,7 @@ public function getPartialRootPaths()
     /**
      * @param string $layoutRootPath
      */
-    public function setLayoutRootPath($layoutRootPath)
+    public function setLayoutRootPath($layoutRootPath): void
     {
         $this->layoutRootPaths = [$layoutRootPath];
     }
@@ -189,7 +195,7 @@ public function setLayoutRootPath($layoutRootPath)
     /**
      * @param string $partialRootPath
      */
-    public function setPartialRootPath($partialRootPath)
+    public function setPartialRootPath($partialRootPath): void
     {
         $this->partialRootPaths = [$partialRootPath];
     }
@@ -205,7 +211,7 @@ public function getPatternReplacementVariables()
     /**
      * @param string[] $patternReplacementVariables
      */
-    public function setPatternReplacementVariables($patternReplacementVariables)
+    public function setPatternReplacementVariables($patternReplacementVariables): void
     {
         $this->patternReplacementVariables = $patternReplacementVariables;
     }
@@ -389,10 +395,10 @@ protected function sanitizePath($path)
      * replaced by the current request format, and once with ."@format" stripped off.
      *
      * @param string $pattern Pattern to be resolved
-     * @param array $patternReplacementVariables The variables to replace in the pattern
+     * @param array<string,mixed> $patternReplacementVariables The variables to replace in the pattern
      * @param boolean $bubbleControllerAndSubpackage if true, then we successively split off parts from "@controller" and "@subpackage" until both are empty.
      * @param boolean $formatIsOptional if true, then half of the resulting strings will have ."@format" stripped off, and the other half will have it.
-     * @return array unix style paths
+     * @return array<mixed> unix style paths
      */
     protected function expandGenericPathPattern($pattern, array $patternReplacementVariables, $bubbleControllerAndSubpackage, $formatIsOptional)
     {
@@ -426,10 +432,10 @@ protected function expandGenericPathPattern($pattern, array $patternReplacementV
     }
 
     /**
-     * @param array $paths
+     * @param array<mixed> $paths
      * @param string $variableName
      * @param string $variableValue
-     * @return array
+     * @return array<mixed>
      */
     protected function replacePatternVariable($paths, $variableName, $variableValue)
     {
@@ -441,11 +447,11 @@ protected function replacePatternVariable($paths, $variableName, $variableValue)
     }
 
     /**
-     * @param array $paths
+     * @param array<string> $paths
      * @param string $controllerName
      * @param string $subPackageKey
      * @param bool $bubbleControllerAndSubpackage
-     * @return array
+     * @return array<string>
      */
     protected function expandSubPackageAndController(array $paths, string $controllerName, string $subPackageKey = '', bool $bubbleControllerAndSubpackage = false): array
     {
@@ -460,7 +466,7 @@ protected function expandSubPackageAndController(array $paths, string $controlle
         $numberOfSubpackageParts = count($subpackageKeyParts);
         $subpackageReplacements = [];
         for ($i = 0; $i <= $numberOfSubpackageParts; $i++) {
-            $subpackageReplacements[] = implode('/', ($i < 0 ? $subpackageKeyParts : array_slice($subpackageKeyParts, $i)));
+            $subpackageReplacements[] = implode('/', array_slice($subpackageKeyParts, $i));
         }
         $paths = $this->expandPatterns($paths, '@subpackage', $subpackageReplacements);
 
@@ -476,10 +482,10 @@ protected function expandSubPackageAndController(array $paths, string $controlle
      * Expands the given $patterns by adding an array element for each $replacement
      * replacing occurrences of $search.
      *
-     * @param array $patterns
+     * @param array<string> $patterns
      * @param string $search
-     * @param array $replacements
-     * @return array
+     * @param array<string> $replacements
+     * @return array<int,string>
      */
     protected function expandPatterns(array $patterns, string $search, array $replacements): array
     {
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/DebugViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/DebugViewHelper.php
index 0b189fa7b2..39d42bc727 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/DebugViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/DebugViewHelper.php
@@ -78,6 +78,6 @@ public function render()
             $expressionToExamine = (is_object($expressionToExamine) ? get_class($expressionToExamine) : gettype($expressionToExamine));
         }
 
-        return \Neos\Flow\var_dump($expressionToExamine, $this->arguments['title'], true);
+        return \Neos\Flow\var_dump($expressionToExamine, $this->arguments['title'], true) ?: '';
     }
 }
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/FlashMessagesViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/FlashMessagesViewHelper.php
index 5198e6ed28..73ccbe633e 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/FlashMessagesViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/FlashMessagesViewHelper.php
@@ -105,7 +105,7 @@ public function render()
      * Render the flash messages as unsorted list. This is triggered if no "as" argument is given
      * to the ViewHelper.
      *
-     * @param list<Message> $flashMessages
+     * @param array<Message> $flashMessages
      * @return string
      */
     protected function renderAsList(array $flashMessages)
@@ -131,7 +131,7 @@ protected function renderAsList(array $flashMessages)
      * the flash messages are stored in the template inside the variable specified
      * in "as".
      *
-     * @param array $flashMessages
+     * @param array<Message> $flashMessages
      * @param string $as
      * @return string
      */
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormFieldViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormFieldViewHelper.php
index 489844b745..a3da57a863 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormFieldViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormFieldViewHelper.php
@@ -84,7 +84,6 @@ protected function getNameWithoutPrefix(): string
             $name = $this->arguments['name'];
         }
         if ($this->hasArgument('value')) {
-            /** @var object $value */
             $value = $this->arguments['value'];
             $multiple = $this->hasArgument('multiple') && $this->arguments['multiple'] === true;
             if (!$multiple
@@ -223,7 +222,7 @@ protected function getPropertyPath(): string
 
             return $formObjectName . '.' . $this->arguments['property'];
         }
-        return rtrim(preg_replace('/(\]\[|\[|\])/', '.', $this->getNameWithoutPrefix()), '.');
+        return rtrim(preg_replace('/(\]\[|\[|\])/', '.', $this->getNameWithoutPrefix()) ?: '', '.');
     }
 
     /**
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormViewHelper.php
index 60aa6d6da6..c58c50daa5 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/AbstractFormViewHelper.php
@@ -41,7 +41,7 @@ public function injectPersistenceManager(PersistenceManagerInterface $persistenc
     /**
      * Prefixes / namespaces the given name with the form field prefix
      *
-     * @param string $fieldName field name to be prefixed
+     * @param ?string $fieldName field name to be prefixed
      * @return string namespaced field name
      */
     protected function prefixFieldName($fieldName)
@@ -68,13 +68,13 @@ protected function prefixFieldName($fieldName)
      * Renders a hidden form field containing the technical identity of the given object.
      *
      * @param object $object Object to create the identity field for
-     * @param string $name Name
+     * @param ?string $name Name
      * @return string A hidden field containing the Identity (UUID in Flow) of the given object or empty string if the object is unknown to the persistence framework
      * @see \Neos\Flow\Mvc\Controller\Argument::setValue()
      */
-    protected function renderHiddenIdentityField($object, $name)
+    protected function renderHiddenIdentityField(object $object, $name)
     {
-        if (!is_object($object) || $this->persistenceManager->isNewObject($object)) {
+        if ($this->persistenceManager->isNewObject($object) || $name === null) {
             return '';
         }
         $identifier = $this->persistenceManager->getIdentifierByObject($object);
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/CheckboxViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/CheckboxViewHelper.php
index d7d4e3b574..67f85cf55b 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/CheckboxViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/CheckboxViewHelper.php
@@ -98,7 +98,8 @@ public function render()
             if ($checked === null) {
                 $checked = false;
                 foreach ($propertyValue as $value) {
-                    if (TypeHandling::isSimpleType(TypeHandling::getTypeForValue($value))) {
+                    $typeForValue = TypeHandling::getTypeForValue($value);
+                    if (TypeHandling::isSimpleType($typeForValue)) {
                         $checked = $valueAttribute === $value;
                     } else {
                         // assume an entity
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/SelectViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/SelectViewHelper.php
index a2dde44370..f9c0f08933 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Form/SelectViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Form/SelectViewHelper.php
@@ -200,7 +200,7 @@ public function render()
     /**
      * Render the option tags.
      *
-     * @param array $options the options for the form.
+     * @param array<mixed> $options the options for the form.
      * @return string rendered tags.
      */
     protected function renderOptionTags($options)
@@ -227,7 +227,7 @@ protected function renderOptionTags($options)
     /**
      * Render the option tags.
      *
-     * @return array an associative array of options, key will be the value of the option tag
+     * @return array<string,mixed> an associative array of options, key will be the value of the option tag
      * @throws ViewHelper\Exception
      */
     protected function getOptions()
@@ -354,6 +354,7 @@ protected function getOptionValueScalar($valueElement)
             } elseif ($this->persistenceManager->getIdentifierByObject($valueElement) !== null) {
                 return $this->persistenceManager->getIdentifierByObject($valueElement);
             } else {
+                /** @phpstan-ignore cast.string (we'll try anyway -.-) */
                 return (string)$valueElement;
             }
         } else {
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/FormViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/FormViewHelper.php
index 9d627d6dcf..3500474fbb 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/FormViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/FormViewHelper.php
@@ -299,7 +299,7 @@ protected function renderHiddenReferrerFields()
         $result = chr(10);
         $request = $this->controllerContext->getRequest();
         $argumentNamespace = null;
-        if ($request instanceof ActionRequest && $request->isMainRequest() === false) {
+        if ($request->isMainRequest() === false) {
             $argumentNamespace = $request->getArgumentNamespace();
 
             $referrer = [
@@ -313,13 +313,10 @@ protected function renderHiddenReferrerFields()
                 $referrerValue = $referrerValue ? htmlspecialchars($referrerValue) : '';
                 $result .= '<input type="hidden" name="' . $argumentNamespace . '[__referrer][' . $referrerKey . ']" value="' . $referrerValue . '" />' . chr(10);
             }
+            /** @var ActionRequest $request we know this since $request is not the main request */
             $request = $request->getParentRequest();
         }
 
-        if ($request === null) {
-            throw new \RuntimeException('No ActionRequest could be found to evaluate form argument namespace.', 1565945918);
-        }
-
         $arguments = $request->getArguments();
         if ($argumentNamespace !== null && isset($arguments[$argumentNamespace])) {
             // A sub request was there; thus we can unset the sub requests arguments,
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/BytesViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/BytesViewHelper.php
index 76a4b946e1..a538a7d88d 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/BytesViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/BytesViewHelper.php
@@ -72,7 +72,7 @@ class BytesViewHelper extends AbstractLocaleAwareViewHelper
 
     /**
      * @param float $bytes
-     * @return array<int, float|string>
+     * @return array{0: float, 1: string}
      */
     protected static function maximizeUnit(float $bytes): array
     {
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CaseViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CaseViewHelper.php
index 9dc3ecd2c2..8eefa16a80 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CaseViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CaseViewHelper.php
@@ -123,7 +123,7 @@ public function render()
     }
 
     /**
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CropViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CropViewHelper.php
index 4ab2986948..e9de2cb5be 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CropViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/CropViewHelper.php
@@ -78,7 +78,7 @@ public function render()
     }
 
     /**
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesDecodeViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesDecodeViewHelper.php
index 0316b42dcc..660c7f2fee 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesDecodeViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesDecodeViewHelper.php
@@ -79,7 +79,7 @@ public function render()
     /**
      * Applies html_entity_decode() on the specified value.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string|mixed
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesViewHelper.php
index a1d67c8532..0f0dbe84ed 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/HtmlentitiesViewHelper.php
@@ -79,7 +79,7 @@ public function render()
     /**
      * Applies htmlentities() on the specified value.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string|mixed
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/JsonViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/JsonViewHelper.php
index 87c216d4d5..d8c7b228e4 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/JsonViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/JsonViewHelper.php
@@ -86,7 +86,7 @@ public function render()
             $options = $options | JSON_FORCE_OBJECT;
         }
 
-        return json_encode($value, $options);
+        return json_encode($value, $options | JSON_THROW_ON_ERROR);
     }
 
     /**
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/PaddingViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/PaddingViewHelper.php
index 476db7b55e..cc37d1f089 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/PaddingViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/PaddingViewHelper.php
@@ -79,7 +79,7 @@ public function render()
     /**
      * Applies str_pad() on the specified value.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/UrlencodeViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/UrlencodeViewHelper.php
index f312b713b2..f0650790bb 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Format/UrlencodeViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Format/UrlencodeViewHelper.php
@@ -72,7 +72,7 @@ public function render()
     /**
      * Applies rawurlencode() on the specified value.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param RenderingContextInterface $renderingContext
      * @return string|mixed
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/RenderChildrenViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/RenderChildrenViewHelper.php
index 9d35aca2ef..1041792388 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/RenderChildrenViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/RenderChildrenViewHelper.php
@@ -74,7 +74,7 @@ public function render(): string
         $widgetChildNodes = $this->getWidgetChildNodes();
 
         $this->addArgumentsToTemplateVariableContainer($this->arguments['arguments']);
-        $output = $widgetChildNodes->evaluate($renderingContext);
+        $output = $widgetChildNodes?->evaluate($renderingContext) ?: '';
         $this->removeArgumentsFromTemplateVariableContainer($this->arguments['arguments']);
 
         return $output;
@@ -97,10 +97,10 @@ protected function getWidgetRenderingContext(): RenderingContextInterface
     }
 
     /**
-     * @return RootNode
+     * @return ?RootNode
      * @throws WidgetContextNotFoundException
      */
-    protected function getWidgetChildNodes(): RootNode
+    protected function getWidgetChildNodes(): ?RootNode
     {
         return $this->getWidgetContext()->getViewHelperChildNodes();
     }
@@ -123,7 +123,7 @@ protected function getWidgetContext(): WidgetContext
     /**
      * Add the given arguments to the TemplateVariableContainer of the widget.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @return void
      * @throws RenderingContextNotFoundException
      * @throws WidgetContextNotFoundException
@@ -139,7 +139,7 @@ protected function addArgumentsToTemplateVariableContainer(array $arguments): vo
     /**
      * Remove the given arguments from the TemplateVariableContainer of the widget.
      *
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @return void
      * @throws RenderingContextNotFoundException
      * @throws WidgetContextNotFoundException
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAccessViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAccessViewHelper.php
index 225621a2e7..e316a8243b 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAccessViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAccessViewHelper.php
@@ -15,7 +15,6 @@
 use Neos\Flow\Security\Authorization\PrivilegeManagerInterface;
 use Neos\Flow\Security\Context;
 use Neos\FluidAdaptor\Core\Rendering\FlowAwareRenderingContextInterface;
-use Neos\FluidAdaptor\Core\Rendering\RenderingContext;
 use Neos\FluidAdaptor\Core\ViewHelper\AbstractConditionViewHelper;
 use TYPO3Fluid\Fluid\Core\Rendering\RenderingContextInterface;
 
@@ -57,7 +56,7 @@ class IfAccessViewHelper extends AbstractConditionViewHelper
     /**
      * Initializes the "then" and "else" arguments
      */
-    public function initializeArguments()
+    public function initializeArguments(): void
     {
         parent::initializeArguments();
         $this->registerArgument('privilegeTarget', 'string', 'Condition expression conforming to Fluid boolean rules', true);
@@ -80,9 +79,9 @@ public function render()
     }
 
     /**
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
-     * @param RenderingContextInterface $renderingContext
+     * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return mixed
      */
     public static function renderStatic(array $arguments, \Closure $renderChildrenClosure, RenderingContextInterface $renderingContext)
@@ -91,28 +90,30 @@ public static function renderStatic(array $arguments, \Closure $renderChildrenCl
     }
 
     /**
-     * @param array|null $arguments
+     * @param array<string,mixed>|null $arguments
      * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return boolean
      */
     protected static function evaluateCondition($arguments, RenderingContextInterface $renderingContext)
     {
         $objectManager = $renderingContext->getObjectManager();
-        /** @var Context $securityContext */
         $securityContext = $objectManager->get(Context::class);
 
-        if ($securityContext !== null && !$securityContext->canBeInitialized()) {
+        if (!$securityContext->canBeInitialized()) {
             return false;
         }
         $privilegeManager = static::getPrivilegeManager($renderingContext);
-        return $privilegeManager->isPrivilegeTargetGranted($arguments['privilegeTarget'], $arguments['parameters'] ?? []);
+        $privilegeTarget = $arguments['privilegeTarget'] ?? null;
+        if (!is_string($privilegeTarget)) {
+            throw new \Exception('Missing privilegeTarget argument.', 1743848049);
+        }
+        return $privilegeManager->isPrivilegeTargetGranted($privilegeTarget, $arguments['parameters'] ?? []);
     }
 
     /**
-     * @param RenderingContext $renderingContext
      * @return PrivilegeManagerInterface
      */
-    protected static function getPrivilegeManager(RenderingContext $renderingContext)
+    protected static function getPrivilegeManager(FlowAwareRenderingContextInterface $renderingContext)
     {
         $objectManager = $renderingContext->getObjectManager();
         return $objectManager->get(PrivilegeManagerInterface::class);
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAuthenticatedViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAuthenticatedViewHelper.php
index a7a78ae4b9..f7f6c6cb1f 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAuthenticatedViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfAuthenticatedViewHelper.php
@@ -66,7 +66,7 @@ public function render()
     }
 
     /**
-     * @param null $arguments
+     * @param array<string,mixed>|null $arguments
      * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return bool
      */
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfHasRoleViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfHasRoleViewHelper.php
index 9be411ea51..5db4eeac33 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfHasRoleViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Security/IfHasRoleViewHelper.php
@@ -79,7 +79,7 @@ class IfHasRoleViewHelper extends AbstractConditionViewHelper
     /**
      * Initializes the "then" and "else" arguments
      */
-    public function initializeArguments()
+    public function initializeArguments(): void
     {
         parent::initializeArguments();
         $this->registerArgument('role', 'mixed', 'The role or role identifier.', true);
@@ -104,7 +104,7 @@ public function render()
     }
 
     /**
-     * @param array|null $arguments
+     * @param array<string,mixed>|null $arguments
      * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return boolean
      */
@@ -120,8 +120,8 @@ protected static function evaluateCondition($arguments, RenderingContextInterfac
             return false;
         }
 
-        $role = $arguments['role'];
-        $account = $arguments['account'];
+        $role = $arguments['role'] ?? null;
+        $account = $arguments['account'] ?? null;
         $packageKey = isset($arguments['packageKey']) ? $arguments['packageKey'] : $renderingContext->getControllerContext()->getRequest()->getControllerPackageKey();
 
         if (is_string($role)) {
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/TranslateViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/TranslateViewHelper.php
index c4c0d06f0b..8db5694bc1 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/TranslateViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/TranslateViewHelper.php
@@ -15,7 +15,6 @@
 use Neos\Flow\I18n\Exception\InvalidLocaleIdentifierException;
 use Neos\Flow\I18n\Locale;
 use Neos\Flow\I18n\Translator;
-use Neos\Flow\Mvc\ActionRequest;
 use Neos\FluidAdaptor\Core\ViewHelper;
 use Neos\FluidAdaptor\Core\ViewHelper\Exception as ViewHelperException;
 
@@ -122,9 +121,7 @@ public function render()
         }
         if ($package === null) {
             $request = $this->renderingContext->getControllerContext()->getRequest();
-            if ($request instanceof ActionRequest) {
-                $package = $request->getControllerPackageKey();
-            }
+            $package = $request->getControllerPackageKey();
             if (empty($package)) {
                 throw new ViewHelperException(
                     'The current package key can\'t be resolved. Make sure to initialize the Fluid view with a proper ActionRequest and/or specify the "package" argument when using the f:translate ViewHelper',
@@ -151,7 +148,7 @@ public function render()
     /**
      * @param Translator $translator
      */
-    public function injectTranslator(Translator $translator)
+    public function injectTranslator(Translator $translator): void
     {
         $this->translator = $translator;
     }
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Uri/ResourceViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Uri/ResourceViewHelper.php
index 6254572c13..9eebbb0346 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Uri/ResourceViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Uri/ResourceViewHelper.php
@@ -100,7 +100,7 @@ public function render()
     }
 
     /**
-     * @param array $arguments
+     * @param array<string,mixed> $arguments
      * @param \Closure $renderChildrenClosure
      * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return string
@@ -145,7 +145,7 @@ public static function renderStatic(array $arguments, \Closure $renderChildrenCl
             $resourcePath = 'resource://' . $package . '/Public/' . $path;
             $localizedResourcePathData = $i18nService->getLocalizedFilename($resourcePath);
             $matches = [];
-            if (preg_match('#resource://([^/]+)/Public/(.*)#', current($localizedResourcePathData), $matches) === 1) {
+            if (preg_match('#resource://([^/]+)/Public/(.*)#', (string)current($localizedResourcePathData), $matches) === 1) {
                 $package = $matches[1];
                 $path = $matches[2];
             }
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Validation/IfHasErrorsViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Validation/IfHasErrorsViewHelper.php
index 3efab8366c..41f1a01f6a 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Validation/IfHasErrorsViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Validation/IfHasErrorsViewHelper.php
@@ -41,11 +41,7 @@
  */
 class IfHasErrorsViewHelper extends AbstractConditionViewHelper
 {
-    /**
-     * @return void
-     * @throws \Neos\FluidAdaptor\Core\ViewHelper\Exception
-     */
-    public function initializeArguments()
+    public function initializeArguments(): void
     {
         $this->registerArgument('then', 'mixed', 'Value to be returned if the condition if met.', false);
         $this->registerArgument('else', 'mixed', 'Value to be returned if the condition if not met.', false);
@@ -70,7 +66,7 @@ public function render()
     }
 
     /**
-     * @param null $arguments
+     * @param array<mixed> $arguments
      * @param FlowAwareRenderingContextInterface&RenderingContextInterface $renderingContext
      * @return boolean
      */
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/AutocompleteController.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/AutocompleteController.php
index 9dd40909a6..a9468b212a 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/AutocompleteController.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/AutocompleteController.php
@@ -21,7 +21,7 @@
 class AutocompleteController extends AbstractWidgetController
 {
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $configuration = ['limit' => 10];
 
@@ -82,6 +82,6 @@ public function autocompleteAction($term)
                 'value' => $val
             ];
         }
-        return json_encode($output);
+        return json_encode($output, JSON_THROW_ON_ERROR);
     }
 }
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/PaginateController.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/PaginateController.php
index 1778c2c0a1..a7b50ed016 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/PaginateController.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/Controller/PaginateController.php
@@ -26,7 +26,7 @@ class PaginateController extends AbstractWidgetController
     protected $objects;
 
     /**
-     * @var array
+     * @var array<string,mixed>
      */
     protected $configuration = ['itemsPerPage' => 10, 'insertAbove' => false, 'insertBelow' => true, 'maximumNumberOfLinks' => 99];
 
@@ -130,16 +130,24 @@ protected function calculateDisplayRange()
     }
 
     /**
-     * Returns an array with the keys "pages", "current", "numberOfPages", "nextPage" & "previousPage"
-     *
-     * @return array
+     * @return array{
+     *     pages: list<array{number: int, isCurrent: bool}>,
+     *     current: int,
+     *     numberOfPages: int,
+     *     displayRangeStart: float,
+     *     displayRangeEnd: float,
+     *     hasLessPages: bool,
+     *     hasMorePages: bool,
+     *     nextPage?: int,
+     *     previousPage?: int,
+     * }
      */
     protected function buildPagination()
     {
         $this->calculateDisplayRange();
         $pages = [];
         for ($i = $this->displayRangeStart; $i <= $this->displayRangeEnd; $i++) {
-            $pages[] = ['number' => $i, 'isCurrent' => ($i === $this->currentPage)];
+            $pages[] = ['number' => (int)$i, 'isCurrent' => ($i == $this->currentPage)];
         }
         $pagination = [
             'pages' => $pages,
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/LinkViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/LinkViewHelper.php
index 55de2b8c53..5a6800624a 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/LinkViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/LinkViewHelper.php
@@ -120,7 +120,7 @@ protected function getAjaxUri(): string
         } else {
             $arguments['__widgetId'] = $widgetContext->getAjaxWidgetIdentifier();
         }
-        return '?' . http_build_query($arguments, null, '&');
+        return '?' . http_build_query(data: $arguments, arg_separator: '&');
     }
 
     /**
diff --git a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/UriViewHelper.php b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/UriViewHelper.php
index f96c6702e2..a57cb01bcf 100644
--- a/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/UriViewHelper.php
+++ b/Neos.FluidAdaptor/Classes/ViewHelpers/Widget/UriViewHelper.php
@@ -104,7 +104,7 @@ protected function getAjaxUri(): string
         } else {
             $arguments['__widgetId'] = $widgetContext->getAjaxWidgetIdentifier();
         }
-        return '?' . http_build_query($arguments, null, '&');
+        return '?' . http_build_query(data: $arguments, arg_separator: '&');
     }
 
     /**
diff --git a/Neos.Http.Factories/Classes/FlowUploadedFile.php b/Neos.Http.Factories/Classes/FlowUploadedFile.php
index e9f5e296cb..be9592c68b 100644
--- a/Neos.Http.Factories/Classes/FlowUploadedFile.php
+++ b/Neos.Http.Factories/Classes/FlowUploadedFile.php
@@ -14,12 +14,12 @@ class FlowUploadedFile extends UploadedFile
      * This is either the persistent identifier of a previously submitted resource file
      * or an array with the "__identity" key set to the persistent identifier.
      *
-     * @var array|string
+     * @var array{__identity: string}|string|null
      */
     protected $originallySubmittedResource;
 
     /**
-     * @var string
+     * @var ?string
      */
     protected $collectionName;
 
@@ -27,7 +27,7 @@ class FlowUploadedFile extends UploadedFile
      * This is either the persistent identifier of a previously submitted resource file
      * or an array with the "__identity" key set to the persistent identifier.
      *
-     * @return array|string
+     * @return array{__identity: string}|string|null
      */
     public function getOriginallySubmittedResource()
     {
@@ -40,15 +40,15 @@ public function getOriginallySubmittedResource()
      * This is either the persistent identifier of a previously submitted resource file
      * or an array with the "__identity" key set to the persistent identifier.
      *
-     * @param array|string $originallySubmittedResource
+     * @param array{__identity: string}|string $originallySubmittedResource
      */
-    public function setOriginallySubmittedResource($originallySubmittedResource)
+    public function setOriginallySubmittedResource($originallySubmittedResource): void
     {
         $this->originallySubmittedResource = $originallySubmittedResource;
     }
 
     /**
-     * @return string
+     * @return ?string
      */
     public function getCollectionName()
     {
@@ -58,7 +58,7 @@ public function getCollectionName()
     /**
      * @param string $collectionName
      */
-    public function setCollectionName($collectionName)
+    public function setCollectionName($collectionName): void
     {
         $this->collectionName = $collectionName;
     }
diff --git a/Neos.Http.Factories/Classes/RequestFactoryTrait.php b/Neos.Http.Factories/Classes/RequestFactoryTrait.php
index 364bfb21de..b840389da0 100644
--- a/Neos.Http.Factories/Classes/RequestFactoryTrait.php
+++ b/Neos.Http.Factories/Classes/RequestFactoryTrait.php
@@ -13,6 +13,7 @@
 trait RequestFactoryTrait
 {
     /**
+     * @param non-empty-string $method
      * @inheritDoc
      */
     public function createRequest(string $method, $uri): RequestInterface
diff --git a/Neos.Http.Factories/Classes/ServerRequestFactoryTrait.php b/Neos.Http.Factories/Classes/ServerRequestFactoryTrait.php
index b4be972e24..58b0e52ac1 100644
--- a/Neos.Http.Factories/Classes/ServerRequestFactoryTrait.php
+++ b/Neos.Http.Factories/Classes/ServerRequestFactoryTrait.php
@@ -56,6 +56,7 @@ public function __construct(
 
     /**
      * @inheritDoc
+     * @param array<string,mixed> $serverParams
      */
     public function createServerRequest(string $method, $uri, array $serverParams = []): ServerRequestInterface
     {
diff --git a/Neos.Http.Factories/Classes/StreamFactoryTrait.php b/Neos.Http.Factories/Classes/StreamFactoryTrait.php
index 6c79adcc84..f8201880bc 100644
--- a/Neos.Http.Factories/Classes/StreamFactoryTrait.php
+++ b/Neos.Http.Factories/Classes/StreamFactoryTrait.php
@@ -18,6 +18,9 @@ trait StreamFactoryTrait
     public function createStream(string $content = ''): StreamInterface
     {
         $fileHandle = fopen('php://temp', 'r+');
+        if (!is_resource($fileHandle)) {
+            throw new \Exception('unable to open php://temp', 1743846274);
+        }
         fwrite($fileHandle, $content);
         rewind($fileHandle);
 
@@ -30,11 +33,15 @@ public function createStream(string $content = ''): StreamInterface
     public function createStreamFromFile(string $filename, string $mode = 'r'): StreamInterface
     {
         $fileHandle = fopen($filename, $mode);
+        if (!is_resource($fileHandle)) {
+            throw new \Exception('unable to open ' . $filename, 1743846243);
+        }
         return $this->createStreamFromResource($fileHandle);
     }
 
     /**
      * @inheritDoc
+     * @param resource $resource
      */
     public function createStreamFromResource($resource): StreamInterface
     {
diff --git a/Neos.Kickstarter/Classes/Command/KickstartCommandController.php b/Neos.Kickstarter/Classes/Command/KickstartCommandController.php
index 246b927c0c..ef9dd18a25 100644
--- a/Neos.Kickstarter/Classes/Command/KickstartCommandController.php
+++ b/Neos.Kickstarter/Classes/Command/KickstartCommandController.php
@@ -49,7 +49,7 @@ class KickstartCommandController extends CommandController
      * @param string $packageType Optional package type, e.g. "neos-plugin"
      * @see neos.flow:package:create
      */
-    public function packageCommand($packageKey, $packageType = PackageInterface::DEFAULT_COMPOSER_TYPE)
+    public function packageCommand($packageKey, $packageType = PackageInterface::DEFAULT_COMPOSER_TYPE): void
     {
         $this->validatePackageKey($packageKey);
 
@@ -101,7 +101,7 @@ public function packageCommand($packageKey, $packageType = PackageInterface::DEF
      * @param boolean $force Overwrite any existing controller or template code. Regardless of this flag, the package, model and repository will never be overwritten.
      * @see neos.kickstarter:kickstart:commandcontroller
      */
-    public function actionControllerCommand($packageKey, $controllerName, $generateActions = false, $generateTemplates = true, $generateFusion = false, $generateRelated = false, $force = false)
+    public function actionControllerCommand($packageKey, $controllerName, $generateActions = false, $generateTemplates = true, $generateFusion = false, $generateRelated = false, $force = false): void
     {
         $subpackageName = '';
         if (strpos($packageKey, '/') !== false) {
@@ -195,7 +195,7 @@ public function actionControllerCommand($packageKey, $controllerName, $generateA
      * @param boolean $force Overwrite any existing controller.
      * @see neos.kickstarter:kickstart:actioncontroller
      */
-    public function commandControllerCommand($packageKey, $controllerName, $force = false)
+    public function commandControllerCommand($packageKey, $controllerName, $force = false): void
     {
         $this->validatePackageKey($packageKey);
         if (!$this->packageManager->isPackageAvailable($packageKey)) {
@@ -222,7 +222,7 @@ public function commandControllerCommand($packageKey, $controllerName, $force =
      * @param boolean $force Overwrite any existing model.
      * @see neos.kickstarter:kickstart:repository
      */
-    public function modelCommand($packageKey, $modelName, $force = false)
+    public function modelCommand($packageKey, $modelName, $force = false): void
     {
         $this->validatePackageKey($packageKey);
         if (!$this->packageManager->isPackageAvailable($packageKey)) {
@@ -264,7 +264,7 @@ public function modelCommand($packageKey, $modelName, $force = false)
      * @param boolean $force Overwrite any existing repository.
      * @see neos.kickstarter:kickstart:model
      */
-    public function repositoryCommand($packageKey, $modelName, $force = false)
+    public function repositoryCommand($packageKey, $modelName, $force = false): void
     {
         $this->validatePackageKey($packageKey);
         if (!$this->packageManager->isPackageAvailable($packageKey)) {
@@ -283,7 +283,7 @@ public function repositoryCommand($packageKey, $modelName, $force = false)
      *
      * @param string $packageKey The package key of the package for the documentation
      */
-    public function documentationCommand($packageKey)
+    public function documentationCommand($packageKey): void
     {
         $this->validatePackageKey($packageKey);
         if (!$this->packageManager->isPackageAvailable($packageKey)) {
@@ -303,7 +303,7 @@ public function documentationCommand($packageKey)
      *
      * @param string $packageKey The package key of the package for the translation
      * @param string $sourceLanguageKey The language key of the default language
-     * @param array $targetLanguageKeys Comma separated language keys for the target translations
+     * @param array<string> $targetLanguageKeys Comma separated language keys for the target translations
      * @return void
      */
     public function translationCommand($packageKey, $sourceLanguageKey, array $targetLanguageKeys = [])
@@ -339,7 +339,7 @@ protected function validatePackageKey($packageKey)
      * @param string $modelName
      * @see http://www.php.net/manual/en/reserved.keywords.php
      */
-    protected function validateModelName($modelName)
+    protected function validateModelName($modelName): void
     {
         if (Validation::isReservedKeyword($modelName)) {
             $this->outputLine('The name of the model cannot be one of the reserved words of PHP!');
diff --git a/Neos.Kickstarter/Classes/Service/GeneratorService.php b/Neos.Kickstarter/Classes/Service/GeneratorService.php
index e872b5f181..7ff7b55ba2 100644
--- a/Neos.Kickstarter/Classes/Service/GeneratorService.php
+++ b/Neos.Kickstarter/Classes/Service/GeneratorService.php
@@ -51,9 +51,9 @@ class GeneratorService
     protected $reflectionService;
 
     /**
-     * @var array
+     * @var array<int,string>
      */
-    protected $generatedFiles = [];
+    protected array $generatedFiles = [];
 
     /**
      * Generate a controller with the given name for the given package
@@ -63,7 +63,7 @@ class GeneratorService
      * @param string $controllerName The name of the new controller
      * @param boolean $fusionView If the controller should default to a FusionView
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateActionController($packageKey, $subpackage, $controllerName, $fusionView = false, $overwrite = false)
     {
@@ -102,7 +102,7 @@ public function generateActionController($packageKey, $subpackage, $controllerNa
      * @param string $controllerName The name of the new controller
      * @param boolean $fusionView If the controller should default to a FusionView
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateCrudController($packageKey, $subpackage, $controllerName, $fusionView = false, $overwrite = false)
     {
@@ -143,7 +143,7 @@ public function generateCrudController($packageKey, $subpackage, $controllerName
      * @param string $packageKey The package key of the controller's package
      * @param string $controllerName The name of the new controller
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateCommandController($packageKey, $controllerName, $overwrite = false)
     {
@@ -179,7 +179,7 @@ public function generateCommandController($packageKey, $controllerName, $overwri
      * @param string $viewName The name of the view
      * @param string $templateName The name of the view
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateView($packageKey, $subpackage, $controllerName, $viewName, $templateName, $overwrite = false)
     {
@@ -199,7 +199,9 @@ public function generateView($packageKey, $subpackage, $controllerName, $viewNam
         $contextVariables['modelFullClassName'] = '\\' . trim($baseNamespace, '\\') . ($subpackage != '' ? '\\' . $subpackage : '') . '\Domain\Model\\' . $controllerName;
         $contextVariables['modelClassName'] = ucfirst($contextVariables['modelName']);
 
-        $modelClassSchema = $this->reflectionService->getClassSchema($contextVariables['modelFullClassName']);
+        $modelClassSchema = class_exists($contextVariables['modelFullClassName'])
+            ? $this->reflectionService->getClassSchema($contextVariables['modelFullClassName'])
+            : null;
         if ($modelClassSchema !== null) {
             $contextVariables['properties'] = $modelClassSchema->getProperties();
             if (isset($contextVariables['properties']['Persistence_Object_Identifier'])) {
@@ -229,7 +231,7 @@ public function generateView($packageKey, $subpackage, $controllerName, $viewNam
      * @param string $packageKey The package key of the controller's package
      * @param string $layoutName The name of the layout
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateLayout($packageKey, $layoutName, $overwrite = false)
     {
@@ -261,7 +263,7 @@ public function generateLayout($packageKey, $layoutName, $overwrite = false)
      * @param string $viewName The name of the view
      * @param string $templateName The name of the view
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateFusion(string $packageKey, string $subpackage, string $controllerName, string $viewName, string $templateName, bool $overwrite = false): array
     {
@@ -281,7 +283,9 @@ public function generateFusion(string $packageKey, string $subpackage, string $c
         $contextVariables['modelFullClassName'] = '\\' . trim($baseNamespace, '\\') . ($subpackage != '' ? '\\' . $subpackage : '') . '\Domain\Model\\' . $controllerName;
         $contextVariables['modelClassName'] = ucfirst($contextVariables['modelName']);
 
-        $modelClassSchema = $this->reflectionService->getClassSchema($contextVariables['modelFullClassName']);
+        $modelClassSchema = class_exists($contextVariables['modelFullClassName'])
+            ? $this->reflectionService->getClassSchema($contextVariables['modelFullClassName'])
+            : null;
         if ($modelClassSchema !== null) {
             $contextVariables['properties'] = $modelClassSchema->getProperties();
             if (isset($contextVariables['properties']['Persistence_Object_Identifier'])) {
@@ -311,7 +315,7 @@ public function generateFusion(string $packageKey, string $subpackage, string $c
      * @param string $packageKey The package key of the controller's package
      * @param string $layoutName The name of the layout
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generatePrototype(string $packageKey, string $layoutName, bool $overwrite = false): array
     {
@@ -340,9 +344,9 @@ public function generatePrototype(string $packageKey, string $layoutName, bool $
      *
      * @param string $packageKey The package key of the controller's package
      * @param string $modelName The name of the new model
-     * @param array $fieldDefinitions The field definitions
+     * @param array<mixed> $fieldDefinitions The field definitions
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateModel($packageKey, $modelName, array $fieldDefinitions, $overwrite = false)
     {
@@ -378,7 +382,7 @@ public function generateModel($packageKey, $modelName, array $fieldDefinitions,
      * @param string $packageKey The package key of the controller's package
      * @param string $modelName The name of the new model fpr which to generate the test
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateTestsForModel($packageKey, $modelName, $overwrite = false)
     {
@@ -411,7 +415,7 @@ public function generateTestsForModel($packageKey, $modelName, $overwrite = fals
      * @param string $packageKey The package key
      * @param string $modelName The name of the model
      * @param boolean $overwrite Overwrite any existing files?
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateRepository($packageKey, $modelName, $overwrite = false)
     {
@@ -443,7 +447,7 @@ public function generateRepository($packageKey, $modelName, $overwrite = false)
      * Generate a documentation skeleton for the package key
      *
      * @param string $packageKey The package key
-     * @return array An array of generated filenames
+     * @return array<int,string> An array of generated filenames
      */
     public function generateDocumentation($packageKey)
     {
@@ -459,7 +463,7 @@ public function generateDocumentation($packageKey)
         $templatePathAndFilename = 'resource://Neos.Kickstarter/Private/Generator/Documentation/Makefile';
         $fileContent = file_get_contents($templatePathAndFilename);
         $targetPathAndFilename = $documentationPath . '/Makefile';
-        $this->generateFile($targetPathAndFilename, $fileContent);
+        $this->generateFile($targetPathAndFilename, $fileContent ?: '');
 
         $templatePathAndFilename = 'resource://Neos.Kickstarter/Private/Generator/Documentation/index.rst';
         $fileContent = $this->renderTemplate($templatePathAndFilename, $contextVariables);
@@ -481,8 +485,8 @@ public function generateDocumentation($packageKey)
      *
      * @param string $packageKey
      * @param string $sourceLanguageKey
-     * @param array $targetLanguageKeys
-     * @return array An array of generated filenames
+     * @param array<string> $targetLanguageKeys
+     * @return array<int,string> An array of generated filenames
      */
     public function generateTranslation($packageKey, $sourceLanguageKey, array $targetLanguageKeys = [])
     {
@@ -516,9 +520,9 @@ public function generateTranslation($packageKey, $sourceLanguageKey, array $targ
     /**
      * Normalize types and prefix types with namespaces
      *
-     * @param array $fieldDefinitions The field definitions
+     * @param array<mixed> $fieldDefinitions The field definitions
      * @param string $namespace The namespace
-     * @return array The normalized and type converted field definitions
+     * @return array<mixed> The normalized and type converted field definitions
      */
     protected function normalizeFieldDefinitions(array $fieldDefinitions, $namespace = '')
     {
@@ -574,7 +578,7 @@ protected function generateFile($targetPathAndFilename, $fileContent, $force = f
      * Render the given template file with the given variables
      *
      * @param string $templatePathAndFilename
-     * @param array $contextVariables
+     * @param array<mixed> $contextVariables
      * @return string
      * @throws \Neos\FluidAdaptor\Core\Exception
      */
@@ -588,7 +592,7 @@ protected function renderTemplate($templatePathAndFilename, array $contextVariab
 
     /**
      * @param PackageInterface $package
-     * @return array
+     * @return array<mixed>
      */
     protected function getPrimaryNamespaceAndEntryPath(PackageInterface $package)
     {
diff --git a/Neos.Kickstarter/Classes/Utility/Inflector.php b/Neos.Kickstarter/Classes/Utility/Inflector.php
index ed402234f7..49fa0eb222 100644
--- a/Neos.Kickstarter/Classes/Utility/Inflector.php
+++ b/Neos.Kickstarter/Classes/Utility/Inflector.php
@@ -56,6 +56,6 @@ public function humanizeCamelCase($camelCased, $lowercase = false)
      */
     protected function spacify($camelCased, $glue = ' ')
     {
-        return preg_replace('/([a-z0-9])([A-Z])/', '$1' . $glue . '$2', $camelCased);
+        return preg_replace('/([a-z0-9])([A-Z])/', '$1' . $glue . '$2', $camelCased) ?: '';
     }
 }
diff --git a/Neos.Utility.Arrays/Classes/Arrays.php b/Neos.Utility.Arrays/Classes/Arrays.php
index 71a44f2aeb..f618721d75 100644
--- a/Neos.Utility.Arrays/Classes/Arrays.php
+++ b/Neos.Utility.Arrays/Classes/Arrays.php
@@ -22,9 +22,9 @@ abstract class Arrays
      * Explodes a $string delimited by $delimiter and passes each item in the array through intval().
      * Corresponds to explode(), but with conversion to integers for all values.
      *
-     * @param string $delimiter Delimiter string to explode with
+     * @param non-empty-string $delimiter Delimiter string to explode with
      * @param string $string The string to explode
-     * @return array Exploded values, all converted to integers
+     * @return array<mixed> Exploded values, all converted to integers
      */
     public static function integerExplode(string $delimiter, string $string): array
     {
@@ -41,10 +41,10 @@ public static function integerExplode(string $delimiter, string $string): array
      * Explodes a string and trims all values for whitespace in the ends.
      * If $onlyNonEmptyValues is set, then all blank ('') values are removed.
      *
-     * @param string $delimiter Delimiter string to explode with
+     * @param non-empty-string $delimiter Delimiter string to explode with
      * @param string $string The string to explode
      * @param boolean $onlyNonEmptyValues If disabled, even empty values (='') will be set in output
-     * @return array Exploded values
+     * @return array<mixed> Exploded values
      */
     public static function trimExplode(string $delimiter, string $string, bool $onlyNonEmptyValues = true): array
     {
@@ -64,11 +64,11 @@ public static function trimExplode(string $delimiter, string $string, bool $only
      * in the first array ($firstArray) with the values of the second array ($secondArray) in case of identical keys,
      * ie. keeping the values of the second.
      *
-     * @param array $firstArray First array
-     * @param array $secondArray Second array, overruling the first array
+     * @param array<mixed> $firstArray First array
+     * @param array<mixed> $secondArray Second array, overruling the first array
      * @param boolean $dontAddNewKeys If set, keys that are NOT found in $firstArray (first array) will not be set. Thus only existing value can/will be overruled from second array.
      * @param boolean $emptyValuesOverride If set (which is the default), values from $secondArray will overrule if they are empty (according to PHP's empty() function)
-     * @return array Resulting array where $secondArray values has overruled $firstArray values
+     * @return array<mixed> Resulting array where $secondArray values has overruled $firstArray values
      */
     public static function arrayMergeRecursiveOverrule(array $firstArray, array $secondArray, bool $dontAddNewKeys = false, bool $emptyValuesOverride = true): array
     {
@@ -109,13 +109,13 @@ public static function arrayMergeRecursiveOverrule(array $firstArray, array $sec
      * Merges two arrays recursively and "binary safe" (integer keys are overridden as well), overruling similar values in the first array ($firstArray) with the values of the second array ($secondArray)
      * In case of identical keys, ie. keeping the values of the second. The given $toArray closure will be used if one of the two array keys contains an array and the other not. It should return an array.
      *
-     * @param array $firstArray First array
-     * @param array $secondArray Second array, overruling the first array
+     * @param array<mixed> $firstArray First array
+     * @param array<mixed> $secondArray Second array, overruling the first array
      * @param \Closure $toArray The given callable will get a value that is not an array and has to return an array.
      *                          This is to allow custom merging of simple types with (sub) arrays
      * @param \Closure|null $overrideFirst The given callable will determine whether the value of the first array should be overridden.
      *                                     It should have the following signature $callable($key, ?array $firstValue = null, ?array $secondValue = null): bool
-     * @return array Resulting array where $secondArray values has overruled $firstArray values
+     * @return array<mixed> Resulting array where $secondArray values has overruled $firstArray values
      */
     public static function arrayMergeRecursiveOverruleWithCallback(array $firstArray, array $secondArray, \Closure $toArray, ?\Closure $overrideFirst = null): array
     {
@@ -157,8 +157,7 @@ public static function arrayMergeRecursiveOverruleWithCallback(array $firstArray
     /**
      * Returns true if the given array contains elements of varying types
      *
-     * @param array $array
-     * @return boolean
+     * @param array<mixed> $array
      */
     public static function containsMultipleTypes(array $array): bool
     {
@@ -179,12 +178,12 @@ public static function containsMultipleTypes(array $array): bool
      * Replacement for array_reduce that allows any type for $initial (instead
      * of only integer)
      *
-     * @param array $array the array to reduce
-     * @param string $function the reduce function with the same order of parameters as in the native array_reduce (i.e. accumulator first, then current array element)
+     * @param array<mixed> $array the array to reduce
+     * @param callable $function the reduce function with the same order of parameters as in the native array_reduce (i.e. accumulator first, then current array element)
      * @param mixed $initial the initial accumulator value
      * @return mixed
      */
-    public static function array_reduce(array $array, string $function, $initial = null)
+    public static function array_reduce(array $array, callable $function, $initial = null)
     {
         $accumulator = $initial;
         foreach ($array as $value) {
@@ -196,8 +195,8 @@ public static function array_reduce(array $array, string $function, $initial = n
     /**
      * Returns the value of a nested array by following the specifed path.
      *
-     * @param array $array The array to traverse
-     * @param array|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
+     * @param array<mixed> $array The array to traverse
+     * @param array<mixed>|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
      * @return mixed The value found, NULL if the path didn't exist (note there is no way to distinguish between a found NULL value and "path not found")
      */
     public static function getValueByPath(array $array, array|string $path): mixed
@@ -222,8 +221,8 @@ public static function getValueByPath(array $array, array|string $path): mixed
      * See {@see ValueAccessor}
      *
      * @internal experimental feature, not stable API
-     * @param array $array The array to traverse
-     * @param array|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
+     * @param array<mixed> $array The array to traverse
+     * @param array<mixed>|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
      * @return ValueAccessor
      */
     public static function getAccessorByPath(array $array, array|string $path): ValueAccessor
@@ -235,21 +234,17 @@ public static function getAccessorByPath(array $array, array|string $path): Valu
     /**
      * Sets the given value in a nested array or object by following the specified path.
      *
-     * @param array|\ArrayAccess $subject The array or ArrayAccess instance to work on
-     * @param array|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
+     * @param array<mixed>|\ArrayAccess<int|string, mixed> $subject The array or ArrayAccess instance to work on
+     * @param array<mixed>|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
      * @param mixed $value The value to set
-     * @return array|\ArrayAccess The modified array or object
+     * @phpstan-return ($subject is array<mixed> ? array<mixed> : \ArrayAccess<int|string, mixed>)
+     * @return array<mixed>|\ArrayAccess<int|string, mixed> The modified array or object
      * @throws \InvalidArgumentException
      */
-    public static function setValueByPath($subject, $path, $value)
+    public static function setValueByPath(array|\ArrayAccess $subject, array|string $path, $value)
     {
-        if (!is_array($subject) && !($subject instanceof \ArrayAccess)) {
-            throw new \InvalidArgumentException('setValueByPath() expects $subject to be array or an object implementing \ArrayAccess, "' . (is_object($subject) ? get_class($subject) : gettype($subject)) . '" given.', 1306424308);
-        }
         if (is_string($path)) {
             $path = explode('.', $path);
-        } elseif (!is_array($path)) {
-            throw new \InvalidArgumentException('setValueByPath() expects $path to be string or array, "' . gettype($path) . '" given.', 1305111499);
         }
         $key = array_shift($path);
         if (count($path) === 0) {
@@ -266,17 +261,15 @@ public static function setValueByPath($subject, $path, $value)
     /**
      * Unsets an element/part of a nested array by following the specified path.
      *
-     * @param array $array The array
-     * @param array|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
-     * @return array The modified array
+     * @param array<mixed> $array The array
+     * @param array<mixed>|string $path The path to follow. Either a simple array of keys or a string in the format 'foo.bar.baz'
+     * @return array<mixed> The modified array
      * @throws \InvalidArgumentException
      */
-    public static function unsetValueByPath(array $array, $path): array
+    public static function unsetValueByPath(array $array, array|string $path): array
     {
         if (is_string($path)) {
             $path = explode('.', $path);
-        } elseif (!is_array($path)) {
-            throw new \InvalidArgumentException('unsetValueByPath() expects $path to be string or array, "' . gettype($path) . '" given.', 1305111513);
         }
         $key = array_shift($path);
         if (count($path) === 0) {
@@ -293,7 +286,7 @@ public static function unsetValueByPath(array $array, $path): array
     /**
      * Sorts multidimensional arrays by recursively calling ksort on its elements.
      *
-     * @param array $array the array to sort
+     * @param array<mixed> $array the array to sort
      * @param integer $sortFlags may be used to modify the sorting behavior using these values (see http://www.php.net/manual/en/function.sort.php)
      * @return boolean true on success, false on failure
      * @see asort()
@@ -314,7 +307,7 @@ public static function sortKeysRecursively(array &$array, int $sortFlags = \SORT
      * Recursively convert an object hierarchy into an associative array.
      *
      * @param mixed $subject An object or array of objects
-     * @return array The subject represented as an array
+     * @return array<mixed> The subject represented as an array
      * @throws \InvalidArgumentException
      */
     public static function convertObjectToArray($subject): array
@@ -336,8 +329,8 @@ public static function convertObjectToArray($subject): array
     /**
      * Recursively removes empty array elements.
      *
-     * @param array $array
-     * @return array the modified array
+     * @param array<mixed> $array
+     * @return array<mixed> the modified array
      */
     public static function removeEmptyElementsRecursively(array $array): array
     {
diff --git a/Neos.Utility.Arrays/Classes/PositionalArraySorter.php b/Neos.Utility.Arrays/Classes/PositionalArraySorter.php
index e900ddd58d..fd05be60ed 100644
--- a/Neos.Utility.Arrays/Classes/PositionalArraySorter.php
+++ b/Neos.Utility.Arrays/Classes/PositionalArraySorter.php
@@ -44,18 +44,33 @@
  */
 final class PositionalArraySorter
 {
+    /**
+     * @var array<mixed>
+     */
     private array $startKeys;
 
+    /**
+     * @var array<mixed>
+     */
     private array $middleKeys;
 
+    /**
+     * @var array<mixed>
+     */
     private array $endKeys;
 
+    /**
+     * @var array<mixed>
+     */
     private array $beforeKeys;
 
+    /**
+     * @var array<mixed>
+     */
     private array $afterKeys;
 
     /**
-     * @param array $subject The source array to sort
+     * @param array<mixed> $subject The source array to sort
      * @param string $positionPropertyPath optional property path to the string that contains the position
      * @param bool $removeNullValues if set to TRUE (default), null-values of the subject are removed
      */
@@ -69,7 +84,7 @@ public function __construct(
     /**
      * Returns a sorted copy of the subject array
      *
-     * @return array
+     * @return array<mixed>
      * @throws Exception\InvalidPositionException
      */
     public function toArray(): array
@@ -87,7 +102,7 @@ public function toArray(): array
      *
      * TODO Detect circles in after / before dependencies (#52185)
      *
-     * @return array an ordered list of keys
+     * @return array<mixed> an ordered list of keys
      * @throws Exception\InvalidPositionException if the positional string has an unsupported format
      */
     public function getSortedKeys(): array
@@ -112,6 +127,8 @@ public function getSortedKeys(): array
      * Extracts all "middle" keys from $arrayKeysWithPosition. Those are all keys with a numeric position.
      * The result is a multidimensional arrays where the KEY of each array is a PRIORITY and the VALUE is an array of matching KEYS
      * This also removes matching keys from the given $arrayKeysWithPosition
+     *
+     * @param array<mixed> $arrayKeysWithPosition
      */
     private function extractMiddleKeys(array &$arrayKeysWithPosition): void
     {
@@ -130,6 +147,8 @@ private function extractMiddleKeys(array &$arrayKeysWithPosition): void
      * Extracts all "start" keys from $arrayKeysWithPosition. Those are all keys with a position starting with "start"
      * The result is a multidimensional arrays where the KEY of each array is a PRIORITY and the VALUE is an array of matching KEYS
      * This also removes matching keys from the given $arrayKeysWithPosition
+     *
+     * @param array<mixed> $arrayKeysWithPosition
      */
     private function extractStartKeys(array &$arrayKeysWithPosition): void
     {
@@ -152,6 +171,8 @@ private function extractStartKeys(array &$arrayKeysWithPosition): void
      * Extracts all "end" keys from $arrayKeysWithPosition. Those are all keys with a position starting with "end"
      * The result is a multidimensional arrays where the KEY of each array is a PRIORITY and the VALUE is an array of matching KEYS
      * This also removes matching keys from the given $arrayKeysWithPosition
+     *
+     * @param array<mixed> $arrayKeysWithPosition
      */
     private function extractEndKeys(array &$arrayKeysWithPosition): void
     {
@@ -174,6 +195,9 @@ private function extractEndKeys(array &$arrayKeysWithPosition): void
      * Extracts all "before" keys from $arrayKeysWithPosition. Those are all keys with a position starting with "before"
      * The result is a multidimensional arrays where the KEY of each array is a PRIORITY and the VALUE is an array of matching KEYS
      * This also removes matching keys from the given $arrayKeysWithPosition
+     *
+     * @param array<mixed> $arrayKeysWithPosition
+     * @param array<mixed> $existingKeys
      */
     private function extractBeforeKeys(array &$arrayKeysWithPosition, array $existingKeys): void
     {
@@ -201,6 +225,9 @@ private function extractBeforeKeys(array &$arrayKeysWithPosition, array $existin
      * Extracts all "after" keys from $arrayKeysWithPosition. Those are all keys with a position starting with "after"
      * The result is a multidimensional arrays where the KEY of each array is a PRIORITY and the VALUE is an array of matching KEYS
      * This also removes matching keys from the given $arrayKeysWithPosition
+     *
+     * @param array<mixed> $arrayKeysWithPosition
+     * @param array<mixed> $existingKeys
      */
     private function extractAfterKeys(array &$arrayKeysWithPosition, array $existingKeys): void
     {
@@ -228,7 +255,7 @@ private function extractAfterKeys(array &$arrayKeysWithPosition, array $existing
      * Collect the array keys inside $this->subject with each position meta-argument.
      * If there is no position but the array is numerically ordered, we use the array index as position.
      *
-     * @return array an associative array where each key of $subject has a position string assigned
+     * @return array<mixed> an associative array where each key of $subject has a position string assigned
      */
     private function collectArrayKeysAndPositions(): array
     {
@@ -253,6 +280,8 @@ private function collectArrayKeysAndPositions(): array
 
     /**
      * Flattens start-, middle-, end-, before- and afterKeys to a single dimension and merges them together to a single array
+     *
+     * @return array<mixed>
      */
     private function generateSortedKeysMap(): array
     {
diff --git a/Neos.Utility.Arrays/Classes/ValueAccessor.php b/Neos.Utility.Arrays/Classes/ValueAccessor.php
index 060ee0c8d7..5bfb0e7852 100644
--- a/Neos.Utility.Arrays/Classes/ValueAccessor.php
+++ b/Neos.Utility.Arrays/Classes/ValueAccessor.php
@@ -47,6 +47,7 @@ public static function forValue(mixed $value): self
 
     /**
      * @internal You should use {@see ValueAccessor::forValue} instead
+     * @param array<mixed> $path
      */
     public static function forValueInPath(mixed $value, array|string $path): self
     {
@@ -97,6 +98,9 @@ public function classString(): string
         throw $this->createTypeError("is not a class-string");
     }
 
+    /**
+     * @return array<mixed>
+     */
     public function array(): array
     {
         if (is_array($this->value)) {
@@ -161,6 +165,9 @@ public function classStringOrNull(): ?string
         throw $this->createTypeError("is not a class-string");
     }
 
+    /**
+     * @return array<mixed>|null
+     */
     public function arrayOrNull(): ?array
     {
         if (is_array($this->value) || is_null($this->value)) {
@@ -182,7 +189,7 @@ public function instanceOfOrNull(string $className): ?object
         throw $this->createTypeError(sprintf('is not an instance of %s or null', $className));
     }
 
-    private function createTypeError($message): \UnexpectedValueException
+    private function createTypeError(string $message): \UnexpectedValueException
     {
         return new \UnexpectedValueException(get_debug_type($this->value) . ' ' . $message . ($this->additionalErrorMessage ? ' ' . $this->additionalErrorMessage : ''));
     }
diff --git a/Neos.Utility.Files/Classes/Files.php b/Neos.Utility.Files/Classes/Files.php
index b0ff9b5b91..136bbed8e4 100644
--- a/Neos.Utility.Files/Classes/Files.php
+++ b/Neos.Utility.Files/Classes/Files.php
@@ -32,7 +32,7 @@ public static function getUnixStylePath(string $path): string
         if (strpos($path, ':') === false) {
             return str_replace(['//', '\\'], '/', $path);
         }
-        return preg_replace('/^([a-z]{2,}):\//', '$1://', str_replace(['//', '\\'], '/', $path));
+        return preg_replace('/^([a-z]{2,}):\//', '$1://', str_replace(['//', '\\'], '/', $path)) ?: '';
     }
 
     /**
@@ -53,7 +53,7 @@ public static function getNormalizedPath(string $path): string
      * Note: trailing slashes will be removed, leading slashes won't.
      * Usage: concatenatePaths(array('dir1/dir2', 'dir3', 'file'))
      *
-     * @param array $paths the file paths to be combined. Last array element may include the filename.
+     * @param array<int,string> $paths the file paths to be combined. Last array element may include the filename.
      * @return string concatenated path without trailing slash.
      * @see getUnixStylePath()
      * @api
@@ -80,10 +80,10 @@ public static function concatenatePaths(array $paths): string
      * directories.
      *
      * @param string $path Path to the directory which shall be read
-     * @param string $suffix If specified, only filenames with this extension are returned (eg. ".php" or "foo.bar")
+     * @param ?string $suffix If specified, only filenames with this extension are returned (eg. ".php" or "foo.bar")
      * @param boolean $returnRealPath If turned on, all paths are resolved by calling realpath()
      * @param boolean $returnDotFiles If turned on, also files beginning with a dot will be returned
-     * @return array Filenames including full path
+     * @return array<int,string> Filenames including full path
      * @api
      */
     public static function readDirectoryRecursively(string $path, ?string $suffix = null, bool $returnRealPath = false, bool $returnDotFiles = false): array
@@ -122,7 +122,7 @@ public static function getRecursiveDirectoryGenerator(string $path, ?string $suf
                     if (is_dir($pathAndFilename)) {
                         array_push($directories, self::getNormalizedPath($pathAndFilename));
                     } elseif ($suffix === null || strpos(strrev($filename), strrev($suffix)) === 0) {
-                        yield static::getUnixStylePath(($returnRealPath === true) ? realpath($pathAndFilename) : $pathAndFilename);
+                        yield static::getUnixStylePath(($returnRealPath === true) ? realpath($pathAndFilename) ?: '' : $pathAndFilename);
                     }
                 }
                 closedir($handle);
@@ -153,6 +153,9 @@ public static function emptyDirectoryRecursively(string $path)
         } else {
             $directoryIterator = new \RecursiveDirectoryIterator($path);
             foreach ($directoryIterator as $fileInfo) {
+                if (is_string($fileInfo)) {
+                    continue;
+                }
                 if (!$fileInfo->isDir()) {
                     if (self::unlink($fileInfo->getPathname()) !== true) {
                         throw new FilesException('Could not unlink file "' . $fileInfo->getPathname() . '".', 1169047619);
@@ -322,14 +325,12 @@ public static function copyDirectoryRecursively(string $sourceDirectory, string
      */
     public static function getFileContents(string $pathAndFilename, int $flags = 0, $context = null, int $offset = 0, int $maximumLength = -1)
     {
-        if ($flags === true) {
-            $flags = FILE_USE_INCLUDE_PATH;
-        }
+        $useIncludePath = ($flags & FILE_USE_INCLUDE_PATH) === 1;
         try {
             if ($maximumLength > -1) {
-                $content = file_get_contents($pathAndFilename, $flags, $context, $offset, $maximumLength);
+                $content = file_get_contents($pathAndFilename, $useIncludePath, $context, $offset, $maximumLength);
             } else {
-                $content = file_get_contents($pathAndFilename, $flags, $context, $offset);
+                $content = file_get_contents($pathAndFilename, $useIncludePath, $context, $offset);
             }
         } catch (ErrorException $ignoredException) {
             $content = false;
@@ -386,7 +387,7 @@ public static function is_link(string $pathAndFilename): bool
             return false;
         }
         $normalizedPathAndFilename = strtolower(rtrim(self::getUnixStylePath($pathAndFilename), '/'));
-        $normalizedTargetPathAndFilename = strtolower(self::getUnixStylePath(realpath($pathAndFilename)));
+        $normalizedTargetPathAndFilename = strtolower(self::getUnixStylePath(realpath($pathAndFilename) ?: ''));
         if ($normalizedTargetPathAndFilename === '') {
             return false;
         }
@@ -431,20 +432,19 @@ public static function unlink(string $pathAndFilename): bool
     /**
      * Supported file size units for the byte conversion functions below
      *
-     * @var array
+     * @var array<string>
      */
-    protected static $sizeUnits = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
+    protected static array $sizeUnits = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
 
     /**
      * Converts an integer with a byte count into human-readable form
      *
-     * @param float|integer $bytes
-     * @param integer $decimals number of decimal places in the resulting string
-     * @param string $decimalSeparator decimal separator of the resulting string
-     * @param string $thousandsSeparator thousands separator of the resulting string
+     * @param integer|null $decimals number of decimal places in the resulting string
+     * @param string|null $decimalSeparator decimal separator of the resulting string
+     * @param string|null $thousandsSeparator thousands separator of the resulting string
      * @return string the size string, e.g. "1,024 MB"
      */
-    public static function bytesToSizeString($bytes, ?int $decimals = null, ?string $decimalSeparator = null, ?string $thousandsSeparator = null): string
+    public static function bytesToSizeString(float|int|string $bytes, ?int $decimals = null, ?string $decimalSeparator = null, ?string $thousandsSeparator = null): string
     {
         if (!is_int($bytes) && !is_float($bytes)) {
             if (is_numeric($bytes)) {
@@ -502,7 +502,7 @@ public static function sizeStringToBytes(string $sizeString): float
         if ($pow === false) {
             throw new FilesException(sprintf('Unknown file size unit "%s"', $matches['unit']), 1417695299);
         }
-        return $size * pow(2, (10 * $pow));
+        return $size * pow(2, (10 * (int)$pow));
     }
 
     /**
diff --git a/Neos.Utility.MediaTypes/Classes/MediaTypes.php b/Neos.Utility.MediaTypes/Classes/MediaTypes.php
index 249d21ced8..65c0db4f0c 100644
--- a/Neos.Utility.MediaTypes/Classes/MediaTypes.php
+++ b/Neos.Utility.MediaTypes/Classes/MediaTypes.php
@@ -33,7 +33,7 @@ abstract class MediaTypes
     /**
      * A map of file extensions to Internet Media Types
      *
-     * @var array
+     * @var array<string,string>
      */
     private static $extensionToMediaType = [
         '3dml' => 'text/vnd.in3d.3dml',
@@ -1027,7 +1027,7 @@ abstract class MediaTypes
     /**
      * A map of Internet Media Types to file extensions
      *
-     * @var array
+     * @var array<string,array<string>>
      */
     private static $mediaTypeToFileExtension = [
         'application/andrew-inset' => ['ez'],
@@ -1821,13 +1821,13 @@ public static function getMediaTypeFromFilename(string $filename): string
      * Returns a Media Type based on the file content
      *
      * @param string $fileContent The file content do determine the media type from
-     * @return string The IANA Internet Media Type
+     * @return string|null The IANA Internet Media Type
      */
-    public static function getMediaTypeFromFileContent(string $fileContent): string
+    public static function getMediaTypeFromFileContent(string $fileContent): ?string
     {
         $fileInfo = new \finfo(FILEINFO_MIME);
-        $mediaType = self::trimMediaType($fileInfo->buffer($fileContent));
-        return isset(self::$mediaTypeToFileExtension[$mediaType]) ? $mediaType : 'application/octet-stream';
+        $mediaType = self::trimMediaType($fileInfo->buffer($fileContent) ?: '');
+        return ($mediaType === null || isset(self::$mediaTypeToFileExtension[$mediaType])) ? $mediaType : 'application/octet-stream';
     }
 
     /**
@@ -1846,7 +1846,7 @@ public static function getFilenameExtensionFromMediaType(string $mediaType): str
      * Returns all possible filename extensions based on the given Media Type.
      *
      * @param string $mediaType The IANA Internet Media Type, for example "text/html"
-     * @return array The corresponding filename extensions, for example ("html", "htm")
+     * @return array<string> The corresponding filename extensions, for example ("html", "htm")
      * @api
      */
     public static function getFilenameExtensionsFromMediaType(string $mediaType): array
@@ -1867,7 +1867,7 @@ public static function getFilenameExtensionsFromMediaType(string $mediaType): ar
      * "parameters" => an array of parameter names and values, array("charset" => "UTF-8")
      *
      * @param string $rawMediaType The raw media type, for example "application/json; charset=UTF-8"
-     * @return array An associative array with parsed information
+     * @return array{type: string, subtype: string, parameters: array<string,string>} An associative array with parsed information
      */
     public static function parseMediaType(string $rawMediaType): array
     {
@@ -1921,9 +1921,9 @@ public static function mediaRangeMatches(string $mediaRange, string $mediaType):
      * and subtype in the format "type/subtype".
      *
      * @param string $rawMediaType The full media type, for example "application/json; charset=UTF-8"
-     * @return string Just the type and subtype, for example "application/json"
+     * @return string|null Just the type and subtype, for example "application/json"
      */
-    public static function trimMediaType(string $rawMediaType)
+    public static function trimMediaType(string $rawMediaType): ?string
     {
         $pieces = self::parseMediaType($rawMediaType);
         return trim(sprintf('%s/%s', $pieces['type'], $pieces['subtype']), '/') ?: null;
diff --git a/Neos.Utility.ObjectHandling/Classes/ObjectAccess.php b/Neos.Utility.ObjectHandling/Classes/ObjectAccess.php
index 89decda676..cb15a28b43 100644
--- a/Neos.Utility.ObjectHandling/Classes/ObjectAccess.php
+++ b/Neos.Utility.ObjectHandling/Classes/ObjectAccess.php
@@ -31,15 +31,15 @@ abstract class ObjectAccess
 {
     /**
      * Internal RuntimeCache for getGettablePropertyNames()
-     * @var array
+     * @var array<string<object>,array<int,string>>
      */
-    protected static $gettablePropertyNamesCache = [];
+    protected static array $gettablePropertyNamesCache = [];
 
     /**
      * Internal RuntimeCache for getPropertyInternal()
-     * @var array
+     * @var array<string,array{accessorMethod?: string, publicProperty?: string}>
      */
-    protected static $propertyGetterCache = [];
+    protected static array $propertyGetterCache = [];
 
     const ACCESS_GET = 0;
     const ACCESS_SET = 1;
@@ -58,22 +58,14 @@ abstract class ObjectAccess
      * - if public property exists, return the value of it.
      * - else, throw exception
      *
-     * @param mixed $subject Object or array to get the property from
+     * @param object|array<mixed> $subject Object or array to get the property from
      * @param string|integer $propertyName Name or index of the property to retrieve
      * @param boolean $forceDirectAccess Directly access property using reflection(!)
      * @return mixed Value of the property
-     * @throws \InvalidArgumentException in case $subject was not an object or $propertyName was not a string
      * @throws PropertyNotAccessibleException if the property was not accessible
      */
-    public static function getProperty($subject, $propertyName, bool $forceDirectAccess = false)
+    public static function getProperty(object|array $subject, string|int $propertyName, bool $forceDirectAccess = false)
     {
-        if (!is_object($subject) && !is_array($subject)) {
-            throw new \InvalidArgumentException('$subject must be an object or array, ' . gettype($subject) . ' given.', 1237301367);
-        }
-        if (!is_string($propertyName) && !is_int($propertyName)) {
-            throw new \InvalidArgumentException('Given property name/index is not of type string or integer.', 1231178303);
-        }
-
         $propertyExists = false;
         $propertyValue = self::getPropertyInternal($subject, $propertyName, $forceDirectAccess, $propertyExists);
         if ($propertyExists === true) {
@@ -91,14 +83,14 @@ public static function getProperty($subject, $propertyName, bool $forceDirectAcc
      * of type string you should use getProperty() instead.
      *
      * @param mixed $subject Object or array to get the property from
-     * @param string $propertyName name of the property to retrieve
+     * @param string|int $propertyName name of the property to retrieve
      * @param boolean $forceDirectAccess directly access property using reflection(!)
      * @param boolean $propertyExists (by reference) will be set to true if the specified property exists and is gettable
      * @return mixed Value of the property
      * @throws PropertyNotAccessibleException
      * @see getProperty()
      */
-    protected static function getPropertyInternal($subject, string $propertyName, bool $forceDirectAccess, bool &$propertyExists)
+    protected static function getPropertyInternal($subject, string|int $propertyName, bool $forceDirectAccess, bool &$propertyExists)
     {
         if ($subject === null) {
             return null;
@@ -111,7 +103,12 @@ protected static function getPropertyInternal($subject, string $propertyName, bo
             return null;
         }
 
+        if (is_int($propertyName)) {
+            throw new \InvalidArgumentException('Cannot use integer property names for objects', 1743799241);
+        }
+
         $propertyExists = true;
+        /** @var string $className safe for objects */
         $className = TypeHandling::getTypeForValue($subject);
 
         if ($forceDirectAccess === true) {
@@ -230,39 +227,33 @@ public static function getPropertyPath($subject, string $propertyPath)
      *   on it without checking if it existed.
      * - else, return false
      *
-     * @param mixed $subject The target object or array
+     * @template T of object
+     * @param array<mixed>|T &$subject The target object or array
      * @param string|integer $propertyName Name or index of the property to set
      * @param mixed $propertyValue Value of the property
      * @param boolean $forceDirectAccess directly access property using reflection(!)
+     * @param-out ($subject is array ? array<mixed> : T) $subject
      * @return boolean true if the property could be set, false otherwise
-     * @throws \InvalidArgumentException in case $object was not an object or $propertyName was not a string
      */
-    public static function setProperty(&$subject, $propertyName, $propertyValue, bool $forceDirectAccess = false): bool
+    public static function setProperty(array|object &$subject, string|int $propertyName, $propertyValue, bool $forceDirectAccess = false): bool
     {
-        if (!is_string($propertyName) && !is_int($propertyName)) {
-            throw new \InvalidArgumentException('Given property name/index is not of type string or integer.', 1231178878);
-        }
-
         if (is_array($subject)) {
             $subject[$propertyName] = $propertyValue;
             return true;
         }
 
-        if (!is_object($subject)) {
-            throw new \InvalidArgumentException('subject must be an object or array, ' . gettype($subject) . ' given.', 1237301368);
-        }
-
         if ($forceDirectAccess === true) {
             if (!is_string($propertyName)) {
                 throw new \InvalidArgumentException('Given property name is not of type string.', 1648244846);
             }
+            /** @var string $className safe for objects */
             $className = TypeHandling::getTypeForValue($subject);
             if (property_exists($className, $propertyName)) {
                 $propertyReflection = new \ReflectionProperty($className, $propertyName);
                 $propertyReflection->setAccessible(true);
                 $propertyReflection->setValue($subject, $propertyValue);
-            } elseif ($subject instanceof ProxyInterface && property_exists(get_parent_class($className), $propertyName)) {
-                $propertyReflection = new \ReflectionProperty(get_parent_class($className), $propertyName);
+            } elseif ($subject instanceof ProxyInterface && property_exists(get_parent_class($className) ?: $className, $propertyName)) {
+                $propertyReflection = new \ReflectionProperty(get_parent_class($className) ?: $className, $propertyName);
                 $propertyReflection->setAccessible(true);
                 $propertyReflection->setValue($subject, $propertyValue);
             } else {
@@ -290,19 +281,17 @@ public static function setProperty(&$subject, $propertyName, $propertyValue, boo
      * - public properties which can be directly get.
      *
      * @param object $object Object to receive property names for
-     * @return array Array of all gettable property names
+     * @return array<int,string> Array of all gettable property names
      * @throws \InvalidArgumentException
      */
-    public static function getGettablePropertyNames($object): array
+    public static function getGettablePropertyNames(object $object): array
     {
-        if (!is_object($object)) {
-            throw new \InvalidArgumentException('$object must be an object, ' . gettype($object) . ' given.', 1237301369);
-        }
         if ($object instanceof \stdClass) {
             $declaredPropertyNames = array_keys(get_object_vars($object));
             $className = 'stdClass';
             unset(self::$gettablePropertyNamesCache[$className]);
         } else {
+            /** @var string $className safe for objects */
             $className = TypeHandling::getTypeForValue($object);
             $declaredPropertyNames = array_keys(get_class_vars($className));
         }
@@ -336,17 +325,15 @@ public static function getGettablePropertyNames($object): array
      * - public properties which can be directly set.
      *
      * @param object $object Object to receive property names for
-     * @return array Array of all settable property names
+     * @return array<int,string> Array of all settable property names
      * @throws \InvalidArgumentException
      */
-    public static function getSettablePropertyNames($object): array
+    public static function getSettablePropertyNames(object $object): array
     {
-        if (!is_object($object)) {
-            throw new \InvalidArgumentException('$object must be an object, ' . gettype($object) . ' given.', 1264022994);
-        }
         if ($object instanceof \stdClass) {
             $declaredPropertyNames = array_keys(get_object_vars($object));
         } else {
+            /** @var string $className safe for object */
             $className = TypeHandling::getTypeForValue($object);
             $declaredPropertyNames = array_keys(get_class_vars($className));
         }
@@ -370,12 +357,9 @@ public static function getSettablePropertyNames($object): array
      * @return boolean
      * @throws \InvalidArgumentException
      */
-    public static function isPropertySettable($object, string $propertyName): bool
+    public static function isPropertySettable(object $object, string $propertyName): bool
     {
-        if (!is_object($object)) {
-            throw new \InvalidArgumentException('$object must be an object, ' . gettype($object) . ' given.', 1259828920);
-        }
-
+        /** @var string $className safe for objects */
         $className = TypeHandling::getTypeForValue($object);
         if (($object instanceof \stdClass && array_key_exists($propertyName, get_object_vars($object))) || array_key_exists($propertyName, get_class_vars($className))) {
             return true;
@@ -391,18 +375,19 @@ public static function isPropertySettable($object, string $propertyName): bool
      * @return boolean
      * @throws \InvalidArgumentException
      */
-    public static function isPropertyGettable($object, string $propertyName): bool
+    public static function isPropertyGettable(object $object, string $propertyName): bool
     {
-        if (!is_object($object)) {
-            throw new \InvalidArgumentException('$object must be an object, ' . gettype($object) . ' given.', 1259828921);
-        }
-        if (($object instanceof \ArrayAccess && $object->offsetExists($propertyName)) || ($object instanceof \stdClass && array_key_exists($propertyName, get_object_vars($object)))) {
+        if (
+            $object instanceof \ArrayAccess && $object->offsetExists($propertyName)
+            || $object instanceof \stdClass && array_key_exists($propertyName, get_object_vars($object))
+        ) {
             return true;
         }
         $uppercasePropertyName = ucfirst($propertyName);
         if (is_callable([$object, 'get' . $uppercasePropertyName]) || is_callable([$object, 'is' . $uppercasePropertyName]) || is_callable([$object, 'has' . $uppercasePropertyName])) {
             return true;
         }
+        /** @var string $className safe for objects */
         $className = TypeHandling::getTypeForValue($object);
         return array_key_exists($propertyName, get_class_vars($className));
     }
@@ -412,15 +397,11 @@ public static function isPropertyGettable($object, string $propertyName): bool
      * $object that are accessible through this class.
      *
      * @param object $object Object to get all properties from.
-     * @return array Associative array of all properties.
-     * @throws \InvalidArgumentException
+     * @return array<string,mixed> Associative array of all properties.
      * @todo What to do with ArrayAccess
      */
-    public static function getGettableProperties($object): array
+    public static function getGettableProperties(object $object): array
     {
-        if (!is_object($object)) {
-            throw new \InvalidArgumentException('$object must be an object, ' . gettype($object) . ' given.', 1237301370);
-        }
         $properties = [];
         foreach (self::getGettablePropertyNames($object) as $propertyName) {
             $propertyExists = false;
diff --git a/Neos.Utility.ObjectHandling/Classes/TypeHandling.php b/Neos.Utility.ObjectHandling/Classes/TypeHandling.php
index c078b86b71..77fc5050a0 100644
--- a/Neos.Utility.ObjectHandling/Classes/TypeHandling.php
+++ b/Neos.Utility.ObjectHandling/Classes/TypeHandling.php
@@ -31,16 +31,16 @@ abstract class TypeHandling
     const LITERAL_TYPE_PATTERN = '/^(?:integer|int|float|double|boolean|bool|string)$/';
 
     /**
-     * @var array
+     * @var array<int,string|class-string<\Traversable<mixed>>>
      */
-    protected static $collectionTypes = ['array', \Traversable::class];
+    protected static array $collectionTypes = ['array', \Traversable::class];
 
     /**
      * Returns an array with type information, including element type for
      * collection types (array, SplObjectStorage, ...)
      *
      * @param string $type Type of the property (see PARSE_TYPE_PATTERN)
-     * @return array An array with information about the type
+     * @return array{type: string, elementType: ?string, nullable: bool} An array with information about the type
      * @throws InvalidTypeException
      */
     public static function parseType(string $type): array
@@ -52,7 +52,7 @@ public static function parseType(string $type): array
 
         $typeWithoutNull = self::stripNullableType($type);
         $isNullable = $typeWithoutNull !== $type || $type === 'null';
-        $type = self::normalizeType($matches['type']);
+        $type = self::normalizeType($matches['type'] ?? '');
         $elementType = isset($matches['elementType']) ? self::normalizeType($matches['elementType']) : null;
 
         if ($elementType !== null && !self::isCollectionType($type)) {
@@ -116,7 +116,7 @@ public static function isSimpleType(string $type): bool
     /**
      * Returns true if the $type is a collection type.
      *
-     * @param string $type
+     * @param string|class-string<object> $type
      * @return boolean
      */
     public static function isCollectionType(string $type): bool
@@ -127,6 +127,7 @@ public static function isCollectionType(string $type): bool
 
         if (class_exists($type) === true || interface_exists($type) === true) {
             foreach (self::$collectionTypes as $collectionType) {
+                /** @phpstan-ignore function.alreadyNarrowedType, identical.alwaysTrue (this can be false) */
                 if (is_subclass_of($type, $collectionType) === true) {
                     return true;
                 }
@@ -185,21 +186,23 @@ public static function stripNullableType($type)
         if (stripos($type, 'null') === false) {
             return $type;
         }
-        return preg_replace('/(\\|null|null\\|)/i', '', $type);
+        return preg_replace('/(\\|null|null\\|)/i', '', $type) ?: '';
     }
 
     /**
      * Return simple type or class for object
      *
      * @param mixed $value
-     * @return string
+     * @return ($value is object ? class-string : string)
      */
     public static function getTypeForValue($value): string
     {
         if (is_object($value)) {
             if ($value instanceof Proxy) {
+                /** @var class-string $type */
                 $type = get_parent_class($value);
             } else {
+                /** @var class-string $type */
                 $type = get_class($value);
             }
         } else {
diff --git a/Neos.Utility.Pdo/Classes/PdoHelper.php b/Neos.Utility.Pdo/Classes/PdoHelper.php
index 873ef34621..40ac1dac76 100644
--- a/Neos.Utility.Pdo/Classes/PdoHelper.php
+++ b/Neos.Utility.Pdo/Classes/PdoHelper.php
@@ -33,7 +33,7 @@ abstract class PdoHelper
      * @param \PDO $databaseHandle
      * @param string $pdoDriver
      * @param string $pathAndFilename
-     * @param array $replacePairs every key in this array will be replaced with the corresponding value in the loaded SQL (example: ['###CACHE_TABLE_NAME###' => 'caches', '###TAGS_TABLE_NAME###' => 'tags'])
+     * @param array<string,string> $replacePairs every key in this array will be replaced with the corresponding value in the loaded SQL (example: ['###CACHE_TABLE_NAME###' => 'caches', '###TAGS_TABLE_NAME###' => 'tags'])
      * @return void
      */
     public static function importSql(\PDO $databaseHandle, string $pdoDriver, string $pathAndFilename, array $replacePairs = [])
@@ -46,13 +46,13 @@ public static function importSql(\PDO $databaseHandle, string $pdoDriver, string
         } else {
             $sql = file($pathAndFilename, FILE_IGNORE_NEW_LINES & FILE_SKIP_EMPTY_LINES);
             // Remove MySQL style key length delimiters (yuck!) if we are not setting up a MySQL db
-            if ($pdoDriver !== 'mysql') {
+            if ($sql !== false && $pdoDriver !== 'mysql') {
                 $sql = preg_replace('/"\([0-9]+\)/', '"', $sql);
             }
         }
 
         $statement = '';
-        foreach ($sql as $line) {
+        foreach ($sql ?: [] as $line) {
             $statement .= ' ' . trim(strtr($line, $replacePairs));
             if (substr($statement, -1) === ';') {
                 $databaseHandle->exec($statement);
diff --git a/Neos.Utility.Schema/Classes/SchemaGenerator.php b/Neos.Utility.Schema/Classes/SchemaGenerator.php
index 07a977c120..5ac82327d2 100644
--- a/Neos.Utility.Schema/Classes/SchemaGenerator.php
+++ b/Neos.Utility.Schema/Classes/SchemaGenerator.php
@@ -26,7 +26,7 @@ class SchemaGenerator
      * Generate a schema for the given value
      *
      * @param mixed $value value to create a schema for
-     * @return array schema as array structure
+     * @return array<string,mixed> schema as array structure
      */
     public function generate($value): array
     {
@@ -62,8 +62,8 @@ public function generate($value): array
     /**
      * Create a schema for a dictionary
      *
-     * @param array $dictionaryValue
-     * @return array
+     * @param array<mixed> $dictionaryValue
+     * @return array{type: string, properties: array<mixed>}
      */
     protected function generateDictionarySchema(array $dictionaryValue): array
     {
@@ -78,8 +78,8 @@ protected function generateDictionarySchema(array $dictionaryValue): array
     /**
      * Create a schema for an array structure
      *
-     * @param array $arrayValue
-     * @return array schema
+     * @param array<mixed> $arrayValue
+     * @return array<string,mixed> schema
      */
     protected function generateArraySchema(array $arrayValue): array
     {
@@ -96,7 +96,7 @@ protected function generateArraySchema(array $arrayValue): array
      * Create a schema for a given string
      *
      * @param string $stringValue
-     * @return array
+     * @return array<string,mixed>
      */
     protected function generateStringSchema(string $stringValue): array
     {
@@ -122,7 +122,7 @@ protected function generateStringSchema(string $stringValue): array
      * Compact an array of items to avoid adding the same value more than once.
      * If the result contains only one item, that item is returned directly.
      *
-     * @param array $values array of values
+     * @param array<mixed> $values array of values
      * @return mixed
      */
     protected function filterDuplicatesFromArray(array $values)
diff --git a/Neos.Utility.Schema/Classes/SchemaValidator.php b/Neos.Utility.Schema/Classes/SchemaValidator.php
index 64fec01df2..82427d9827 100644
--- a/Neos.Utility.Schema/Classes/SchemaValidator.php
+++ b/Neos.Utility.Schema/Classes/SchemaValidator.php
@@ -69,7 +69,7 @@ class SchemaValidator
      *
      * @param mixed $value value to validate
      * @param mixed $schema type as string, schema or array of schemas
-     * @param array $types the additional type schemas
+     * @param array<mixed> $types the additional type schemas
      * @return ErrorResult
      */
     public function validate($value, $schema, array $types = []): ErrorResult
@@ -147,8 +147,8 @@ public function validate($value, $schema, array $types = []): ErrorResult
      * Validate a value for a given type
      *
      * @param mixed $value
-     * @param array $schema
-     * @param array $types
+     * @param array<string,mixed> $schema
+     * @param array<mixed> $types
      * @return ErrorResult
      */
     protected function validateType($value, array $schema, array $types = []): ErrorResult
@@ -209,8 +209,8 @@ protected function validateType($value, array $schema, array $types = []): Error
      * Validate a value with a given list of allowed types
      *
      * @param mixed $value
-     * @param array $schema
-     * @param array $types
+     * @param array<string,mixed> $schema
+     * @param array<mixed> $types
      * @return ErrorResult
      */
     protected function validateTypeArray($value, array $schema, array $types = []): ErrorResult
@@ -254,7 +254,7 @@ protected function validateTypeArray($value, array $schema, array $types = []):
      * - divisibleBy : value is divisibleBy the given number
      *
      * @param mixed $value
-     * @param array $schema
+     * @param array<string,mixed> $schema
      * @return ErrorResult
      */
     protected function validateNumberType($value, array $schema): ErrorResult
@@ -305,7 +305,7 @@ protected function validateNumberType($value, array $schema): ErrorResult
      *
      * @see SchemaValidator::validateNumberType
      * @param mixed $value
-     * @param array $schema
+     * @param array<mixed> $schema
      * @return ErrorResult
      */
     protected function validateIntegerType($value, array $schema): ErrorResult
@@ -323,7 +323,7 @@ protected function validateIntegerType($value, array $schema): ErrorResult
      * Validate a boolean value with the given schema
      *
      * @param mixed $value
-     * @param array $schema
+     * @param array<mixed> $schema
      * @return ErrorResult
      */
     protected function validateBooleanType($value, array $schema): ErrorResult
@@ -346,8 +346,8 @@ protected function validateBooleanType($value, array $schema): ErrorResult
      * - uniqueItems : allow only unique values
      *
      * @param mixed $value
-     * @param array $schema
-     * @param array $types
+     * @param array<string,mixed> $schema
+     * @param array<mixed> $types
      * @return ErrorResult
      */
     protected function validateArrayType($value, array $schema, array $types = []): ErrorResult
@@ -404,8 +404,8 @@ protected function validateArrayType($value, array $schema, array $types = []):
      * - additionalProperties : if false is given all additionalProperties are forbidden, if a schema is given all additional properties have to match the schema
      *
      * @param mixed $value
-     * @param array $schema
-     * @param array $types
+     * @param array<int|string,mixed> $schema
+     * @param array<int|string,mixed> $types
      * @return ErrorResult
      */
     protected function validateDictionaryType($value, array $schema, array $types = []): ErrorResult
@@ -496,8 +496,8 @@ protected function validateDictionaryType($value, array $schema, array $types =
      *   [date-time|date|time|uri|email|ipv4|ipv6|ip-address|host-name|class-name|interface-name]
      *
      * @param mixed $value
-     * @param array $schema
-     * @param array $types
+     * @param array<string,mixed> $schema
+     * @param array<mixed> $types
      * @return ErrorResult
      */
     protected function validateStringType($value, array $schema, array $types = []): ErrorResult
@@ -530,6 +530,7 @@ protected function validateStringType($value, array $schema, array $types = []):
             switch ($schema['format']) {
                 case 'date-time':
                     // YYYY-MM-DDThh:mm:ssZ ISO8601
+                    /** @phpstan-ignore staticMethod.resultUnused (we only care about the error) */
                     \DateTime::createFromFormat(\DateTime::ISO8601, $value);
                     $parseErrors = \DateTime::getLastErrors();
                     if ($parseErrors && $parseErrors['error_count'] > 0) {
@@ -538,6 +539,7 @@ protected function validateStringType($value, array $schema, array $types = []):
                     break;
                 case 'date':
                     // YYYY-MM-DD
+                    /** @phpstan-ignore staticMethod.resultUnused (we only care about the error) */
                     \DateTime::createFromFormat('Y-m-d', $value);
                     $parseErrors = \DateTime::getLastErrors();
                     if ($parseErrors && $parseErrors['error_count'] > 0) {
@@ -546,6 +548,7 @@ protected function validateStringType($value, array $schema, array $types = []):
                     break;
                 case 'time':
                     // hh:mm:ss
+                    /** @phpstan-ignore staticMethod.resultUnused (we only care about the error) */
                     \DateTime::createFromFormat('H:i:s', $value);
                     $parseErrors = \DateTime::getLastErrors();
                     if ($parseErrors && $parseErrors['error_count'] > 0) {
@@ -604,7 +607,7 @@ protected function validateStringType($value, array $schema, array $types = []):
      * Validate a null value with the given schema
      *
      * @param mixed $value
-     * @param array $schema
+     * @param array<mixed> $schema
      * @return ErrorResult
      */
     protected function validateNullType($value, array $schema): ErrorResult
@@ -620,7 +623,7 @@ protected function validateNullType($value, array $schema): ErrorResult
      * Validate any value with the given schema. Return always a valid Result.
      *
      * @param mixed $value
-     * @param array $schema
+     * @param array<int|string,mixed> $schema
      * @return ErrorResult
      */
     protected function validateAnyType($value, array $schema): ErrorResult
@@ -665,7 +668,7 @@ protected function createError(string $expectation, $value = null): Error
      * Determine whether the given php array is a schema or not
      *
      * @todo there should be a more sophisticated way to detect schemas
-     * @param array $phpArray
+     * @param array<int|string, mixed> $phpArray
      * @return boolean
      */
     protected function isSchema(array $phpArray): bool
@@ -677,7 +680,7 @@ protected function isSchema(array $phpArray): bool
     /**
      * Determine whether the given php array is a plain numerically indexed array
      *
-     * @param array $phpArray
+     * @param array<int|string,mixed> $phpArray
      * @return boolean
      */
     protected function isNumericallyIndexedArray(array $phpArray): bool
@@ -693,7 +696,7 @@ protected function isNumericallyIndexedArray(array $phpArray): bool
     /**
      * Determine whether the given php array is a Dictionary (has no numeric identifiers)
      *
-     * @param array $phpArray
+     * @param array<int|string, mixed> $phpArray
      * @return boolean
      */
     protected function isDictionary(array $phpArray): bool
diff --git a/Neos.Utility.Unicode/Classes/Functions.php b/Neos.Utility.Unicode/Classes/Functions.php
index a13429ebb5..806227f83d 100644
--- a/Neos.Utility.Unicode/Classes/Functions.php
+++ b/Neos.Utility.Unicode/Classes/Functions.php
@@ -31,7 +31,7 @@ public static function strtotitle(string $string): string
     {
         $result = '';
         $splitIntoLowerCaseWords = preg_split("/([\n\r\t ])/", self::strtolower($string), -1, PREG_SPLIT_DELIM_CAPTURE);
-        foreach ($splitIntoLowerCaseWords as $delimiterOrValue) {
+        foreach ($splitIntoLowerCaseWords  ?: [] as $delimiterOrValue) {
             $result .= self::strtoupper(self::substr($delimiterOrValue, 0, 1)) . self::substr($delimiterOrValue, 1);
         }
         return $result;
@@ -133,7 +133,7 @@ public static function lcfirst(string $string): string
      * @param string $haystack UTF-8 string to search in
      * @param string $needle UTF-8 string to search for
      * @param integer $offset Positition to start the search
-     * @return integer The character position
+     * @return integer|false The character position
      * @api
      */
     public static function strpos(string $haystack, string $needle, int $offset = 0)
@@ -154,16 +154,19 @@ public static function strpos(string $haystack, string $needle, int $offset = 0)
      * @see http://www.php.net/manual/en/function.pathinfo.php
      *
      * @param string $path
-     * @param integer $options Optional, one of PATHINFO_DIRNAME, PATHINFO_BASENAME, PATHINFO_EXTENSION or PATHINFO_FILENAME.
-     * @return string|array
+     * @param integer|null $options Optional, one of PATHINFO_DIRNAME, PATHINFO_BASENAME, PATHINFO_EXTENSION or PATHINFO_FILENAME.
+     * @return ($options is null ? array{dirname: string, basename: string, extension: string, filename: string} : string)
      * @api
      */
-    public static function pathinfo(string $path, ?int $options = null)
+    public static function pathinfo(string $path, ?int $options = null): string|array
     {
+        /** @var string $currentLocale we assume the current locale to be properly set */
+        /** @phpstan-ignore argument.type (int is allowed for locales) */
         $currentLocale = setlocale(LC_CTYPE, 0);
         // Before we have a setting for setlocale, his should suffice for pathinfo
         // to work correctly on Unicode strings
         setlocale(LC_CTYPE, 'en_US.UTF-8');
+        /** @var string|array{dirname: string, basename: string, extension: string, filename: string} $pathinfo */
         $pathinfo = $options == null ? pathinfo($path) : pathinfo($path, $options);
         setlocale(LC_CTYPE, $currentLocale);
         return $pathinfo;
@@ -188,8 +191,11 @@ public static function parse_url(string $url, int $component = -1)
         $encodedUrl = preg_replace_callback('%[^:@/?#&=\.]+%usD', function ($matches) {
             return urlencode($matches[0]);
         }, $url);
-        $components = parse_url($encodedUrl);
+        if ($encodedUrl === null) {
+            return false;
+        }
 
+        $components = parse_url($encodedUrl);
         if ($components === false) {
             return false;
         }
diff --git a/Neos.Utility.Unicode/Classes/TextIterator.php b/Neos.Utility.Unicode/Classes/TextIterator.php
index 862a05c204..2af09dd48d 100644
--- a/Neos.Utility.Unicode/Classes/TextIterator.php
+++ b/Neos.Utility.Unicode/Classes/TextIterator.php
@@ -19,6 +19,7 @@
 /**
  * A UTF8-aware TextIterator
  *
+ * @implements \Iterator<int,string>
  */
 class TextIterator implements \Iterator
 {
@@ -68,12 +69,12 @@ class TextIterator implements \Iterator
     protected $currentPosition;
 
     /**
-     * @var \ArrayObject
+     * @var \ArrayObject<int,TextIteratorElement>
      */
     protected $iteratorCache;
 
     /**
-     * @var \ArrayIterator
+     * @var \ArrayIterator<int,TextIteratorElement>
      */
     protected $iteratorCacheIterator;
 
@@ -109,11 +110,11 @@ public function __construct(string $subject, int $iteratorType = self::CHARACTER
     /**
      * Returns the current element
      *
-     * @return string The value of the current element
+     * @return string|null The value of the current element
      */
-    public function current(): string
+    public function current(): ?string
     {
-        return $this->getCurrentElement()->getValue();
+        return $this->getCurrentElement()?->getValue();
     }
 
     /**
@@ -123,7 +124,7 @@ public function current(): string
      */
     public function next(): void
     {
-        $this->previousElement = $this->getCurrentElement();
+        $this->previousElement = $this->getCurrentElement() ?: $this->previousElement;
         $this->iteratorCacheIterator->next();
     }
 
@@ -164,11 +165,11 @@ public function rewind(): void
     /**
      * Returns the offset in the original given string of the current element
      *
-     * @return integer The offset of the current element
+     * @return int|null The offset of the current element, if any
      */
-    public function offset(): int
+    public function offset(): ?int
     {
-        return $this->getCurrentElement()->getOffset();
+        return $this->getCurrentElement()?->getOffset();
     }
 
     /**
@@ -194,7 +195,8 @@ public function last(): string
             $previousElement = $this->getCurrentElement();
             $this->next();
         }
-        return $previousElement->getValue();
+        // can never be null because the iterator cannot be empty
+        return $previousElement?->getValue() ?: '';
     }
 
     /**
@@ -202,15 +204,15 @@ public function last(): string
      * given by its offset
      *
      * @param integer $offset The offset of the character
-     * @return int The offset of the element following this character
+     * @return int|null The offset of the element following this character or null if the offset is out of bounds
      */
-    public function following(int $offset): int
+    public function following(int $offset): ?int
     {
         $this->rewind();
         while ($this->valid()) {
             $this->next();
             $nextElement = $this->getCurrentElement();
-            if ($nextElement->getOffset() >= $offset) {
+            if ($nextElement && $nextElement->getOffset() >= $offset) {
                 return $nextElement->getOffset();
             }
         }
@@ -231,7 +233,7 @@ public function preceding(int $offset): int
             $previousElement = $this->getCurrentElement();
             $this->next();
             $currentElement = $this->getCurrentElement();
-            if (($currentElement->getOffset() + $currentElement->getLength()) >= $offset) {
+            if ($previousElement && $currentElement && ($currentElement->getOffset() + $currentElement->getLength()) >= $offset) {
                 return $previousElement->getOffset() + $previousElement->getLength();
             }
         }
@@ -254,20 +256,21 @@ public function preceding(int $offset): int
      */
     public function isBoundary(): bool
     {
-        return $this->getCurrentElement()->isBoundary();
+        return $this->getCurrentElement()?->isBoundary() ?: false;
     }
 
     /**
      * Returns all elements of the iterator in an array
      *
-     * @return array All elements of the iterator
+     * @return array<int,string> All elements of the iterator
      */
     public function getAll(): array
     {
         $this->rewind();
         $allValues = [];
         while ($this->valid()) {
-            $allValues[] = $this->getCurrentElement()->getValue();
+            // will never be null while valid
+            $allValues[] = $this->getCurrentElement()?->getValue() ?: '';
             $this->next();
         }
         return $allValues;
@@ -276,7 +279,7 @@ public function getAll(): array
     /**
      * @throws UnsupportedFeatureException
      */
-    public function getRuleStatus()
+    public function getRuleStatus(): never
     {
         throw new UnsupportedFeatureException('getRuleStatus() is not supported.', 1210849057);
     }
@@ -284,7 +287,7 @@ public function getRuleStatus()
     /**
      * @throws UnsupportedFeatureException
      */
-    public function getRuleStatusArray()
+    public function getRuleStatusArray(): never
     {
         throw new UnsupportedFeatureException('getRuleStatusArray() is not supported.', 1210849076);
     }
@@ -292,7 +295,7 @@ public function getRuleStatusArray()
     /**
      * @throws UnsupportedFeatureException
      */
-    public function getAvailableLocales()
+    public function getAvailableLocales(): never
     {
         throw new UnsupportedFeatureException('getAvailableLocales() is not supported.', 1210849105);
     }
@@ -305,7 +308,8 @@ public function getAvailableLocales()
     public function first(): string
     {
         $this->rewind();
-        return $this->getCurrentElement()->getValue();
+        // can never be empty, will at least contain empty string
+        return $this->getCurrentElement()?->getValue() ?: '';
     }
 
     /**
@@ -346,7 +350,7 @@ private function generateIteratorElements()
     private function parseSubjectByCharacter(): void
     {
         $i = 0;
-        foreach (preg_split('//u', $this->subject) as $currentCharacter) {
+        foreach (preg_split('//u', $this->subject) ?: [] as $currentCharacter) {
             if ($currentCharacter === '') {
                 continue;
             }
@@ -373,7 +377,7 @@ private function parseSubjectByWord()
                 $this->iteratorCache->append(new TextIteratorElement(' ', $i, 1, true));
 
                 $j = 0;
-                $splittedWord = preg_split('/' . self::REGEXP_SENTENCE_DELIMITERS . '/', $currentWord);
+                $splittedWord = preg_split('/' . self::REGEXP_SENTENCE_DELIMITERS . '/', $currentWord) ?: [];
                 foreach ($splittedWord as $currentPart) {
                     if ($currentPart !== '') {
                         $this->iteratorCache->append(new TextIteratorElement($currentPart, $i, Unicode\Functions::strlen($currentPart), false));
@@ -442,7 +446,7 @@ private function parseSubjectBySentence()
         $count = 0;
         $delimitersMatches = [];
         preg_match_all('/' . self::REGEXP_SENTENCE_DELIMITERS . '/', $this->subject, $delimitersMatches);
-        $splittedSentence = preg_split('/' . self::REGEXP_SENTENCE_DELIMITERS . '/', $this->subject);
+        $splittedSentence = preg_split('/' . self::REGEXP_SENTENCE_DELIMITERS . '/', $this->subject) ?: [];
 
         if (count($splittedSentence) == 1) {
             $this->iteratorCache->append(new TextIteratorElement($splittedSentence[0], 0, Unicode\Functions::strlen($splittedSentence[0]), false));
@@ -480,6 +484,7 @@ private function parseSubjectBySentence()
      * Helper function to get the current element from the cache.
      *
      * @return TextIteratorElement|null The current element of the cache
+     * @phpstan-ignore return.unusedType (can be null if next() leaves the valid range of the iterator)
      */
     private function getCurrentElement()
     {
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 9b730bf93b..6eaf9d56c1 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -1,5 +1,5 @@
 parameters:
-    level: 3
+    level: 8
     paths:
         - Neos.Cache/Classes
         - Neos.Eel/Classes
@@ -29,3 +29,6 @@ parameters:
             - Neos.Eel/Classes/InterpretedEelParser.php
             - Neos.Eel/Classes/CompilingEelParser.php
             - Neos.Flow/Classes/Security/Authorization/Privilege/Entity/Doctrine/EntityPrivilegeExpressionEvaluator.php
+    scanDirectories:
+        - Neos.Flow/Tests
+        - Neos.Flow/Classes/Error