diff --git a/.phpstan.dist.baselines/argument.type.php b/.phpstan.dist.baselines/argument.type.php
index bc930b84ca9..978d1928811 100644
--- a/.phpstan.dist.baselines/argument.type.php
+++ b/.phpstan.dist.baselines/argument.type.php
@@ -951,16 +951,6 @@
     'count' => 2,
     'path' => __DIR__ . '/../app/code/core/Mage/Api/Model/Wsdl/Config/Element.php',
 ];
-$ignoreErrors[] = [
-    'rawMessage' => 'Parameter #1 $array of function uasort expects array, array|string given.',
-    'count' => 1,
-    'path' => __DIR__ . '/../app/code/core/Mage/Api2/Helper/Data.php',
-];
-$ignoreErrors[] = [
-    'rawMessage' => 'Parameter #2 $string of function explode expects string, string|true given.',
-    'count' => 1,
-    'path' => __DIR__ . '/../app/code/core/Mage/Api2/Helper/Data.php',
-];
 $ignoreErrors[] = [
     'rawMessage' => 'Parameter #1 $roleId of method Mage_Api2_Model_Acl::addRole() expects int, int|string|null given.',
     'count' => 1,
diff --git a/.phpstan.dist.baselines/booleanNot.exprNotBoolean.php b/.phpstan.dist.baselines/booleanNot.exprNotBoolean.php
index 3f04f86addb..0977686bf4f 100644
--- a/.phpstan.dist.baselines/booleanNot.exprNotBoolean.php
+++ b/.phpstan.dist.baselines/booleanNot.exprNotBoolean.php
@@ -1111,11 +1111,6 @@
     'count' => 1,
     'path' => __DIR__ . '/../app/code/core/Mage/Api/Model/Wsdl/Config/Element.php',
 ];
-$ignoreErrors[] = [
-    'rawMessage' => 'Only booleans are allowed in a negated boolean, Mage_Core_Model_Config_Element|false given.',
-    'count' => 1,
-    'path' => __DIR__ . '/../app/code/core/Mage/Api2/Helper/Data.php',
-];
 $ignoreErrors[] = [
     'rawMessage' => 'Only booleans are allowed in a negated boolean, array given.',
     'count' => 1,
diff --git a/.phpstan.dist.baselines/foreach.nonIterable.php b/.phpstan.dist.baselines/foreach.nonIterable.php
index 4e240a0e480..ae5aed2efd2 100644
--- a/.phpstan.dist.baselines/foreach.nonIterable.php
+++ b/.phpstan.dist.baselines/foreach.nonIterable.php
@@ -96,11 +96,6 @@
     'count' => 1,
     'path' => __DIR__ . '/../app/code/core/Mage/Api/Model/Resource/User.php',
 ];
-$ignoreErrors[] = [
-    'rawMessage' => 'Argument of an invalid type array|string supplied for foreach, only iterables are supported.',
-    'count' => 2,
-    'path' => __DIR__ . '/../app/code/core/Mage/Api2/Helper/Data.php',
-];
 $ignoreErrors[] = [
     'rawMessage' => 'Argument of an invalid type list<string>|false supplied for foreach, only iterables are supported.',
     'count' => 1,
diff --git a/.phpstan.dist.baselines/function.strict.php b/.phpstan.dist.baselines/function.strict.php
index ee1b3c51959..05bd3efe0c7 100644
--- a/.phpstan.dist.baselines/function.strict.php
+++ b/.phpstan.dist.baselines/function.strict.php
@@ -311,11 +311,6 @@
     'count' => 2,
     'path' => __DIR__ . '/../app/code/core/Mage/Api/Model/Wsdl/Config/Base.php',
 ];
-$ignoreErrors[] = [
-    'rawMessage' => 'Call to function in_array() requires parameter #3 to be set.',
-    'count' => 1,
-    'path' => __DIR__ . '/../app/code/core/Mage/Api2/Helper/Data.php',
-];
 $ignoreErrors[] = [
     'rawMessage' => 'Call to function in_array() requires parameter #3 to be set.',
     'count' => 1,
diff --git a/.phpstan.dist.baselines/if.condNotBoolean.php b/.phpstan.dist.baselines/if.condNotBoolean.php
index d0010742a10..5ecfa9830e5 100644
--- a/.phpstan.dist.baselines/if.condNotBoolean.php
+++ b/.phpstan.dist.baselines/if.condNotBoolean.php
@@ -2121,11 +2121,6 @@
     'count' => 1,
     'path' => __DIR__ . '/../app/code/core/Mage/Api2/Block/Adminhtml/Permissions/User/Edit/Tab/Roles.php',
 ];
-$ignoreErrors[] = [
-    'rawMessage' => 'Only booleans are allowed in an if condition, Mage_Core_Model_Config_Element|false given.',
-    'count' => 1,
-    'path' => __DIR__ . '/../app/code/core/Mage/Api2/Helper/Data.php',
-];
 $ignoreErrors[] = [
     'rawMessage' => 'Only booleans are allowed in an if condition, array given.',
     'count' => 1,
diff --git a/.phpstan.dist.baselines/method.nonObject.php b/.phpstan.dist.baselines/method.nonObject.php
index 04ed310b7ff..05bacb6f8f9 100644
--- a/.phpstan.dist.baselines/method.nonObject.php
+++ b/.phpstan.dist.baselines/method.nonObject.php
@@ -2001,11 +2001,6 @@
     'count' => 1,
     'path' => __DIR__ . '/../app/code/core/Mage/Api2/Block/Adminhtml/Roles/Tab/Users.php',
 ];
-$ignoreErrors[] = [
-    'rawMessage' => 'Cannot call method getNode() on Mage_Core_Model_Config|null.',
-    'count' => 2,
-    'path' => __DIR__ . '/../app/code/core/Mage/Api2/Helper/Data.php',
-];
 $ignoreErrors[] = [
     'rawMessage' => 'Cannot call method children() on array|Varien_Simplexml_Element.',
     'count' => 1,
diff --git a/.phpstan.dist.baselines/return.type.php b/.phpstan.dist.baselines/return.type.php
index f68913cdf90..b1478d61e93 100644
--- a/.phpstan.dist.baselines/return.type.php
+++ b/.phpstan.dist.baselines/return.type.php
@@ -431,11 +431,6 @@
     'count' => 1,
     'path' => __DIR__ . '/../app/code/core/Mage/Api/Model/User.php',
 ];
-$ignoreErrors[] = [
-    'rawMessage' => 'Method Mage_Api2_Helper_Data::getAuthAdapters() should return array but returns array|string.',
-    'count' => 1,
-    'path' => __DIR__ . '/../app/code/core/Mage/Api2/Helper/Data.php',
-];
 $ignoreErrors[] = [
     'rawMessage' => 'Method Mage_Api2_Model_Config::getResourceAttributes() should return array but returns array|string.',
     'count' => 1,
diff --git a/.phpstan.dist.baselines/variable.undefined.php b/.phpstan.dist.baselines/variable.undefined.php
index 71a65a78611..0b5545ed0f5 100644
--- a/.phpstan.dist.baselines/variable.undefined.php
+++ b/.phpstan.dist.baselines/variable.undefined.php
@@ -6,11 +6,6 @@
     'count' => 2,
     'path' => __DIR__ . '/../app/code/core/Mage/Adminhtml/Model/Sales/Order/Create.php',
 ];
-$ignoreErrors[] = [
-    'rawMessage' => 'Variable $adapters might not be defined.',
-    'count' => 1,
-    'path' => __DIR__ . '/../app/code/core/Mage/Api2/Helper/Data.php',
-];
 $ignoreErrors[] = [
     'rawMessage' => 'Variable $operationName might not be defined.',
     'count' => 2,
diff --git a/app/code/core/Mage/Api2/Helper/Data.php b/app/code/core/Mage/Api2/Helper/Data.php
index b0404ed7d46..ccc8822a766 100644
--- a/app/code/core/Mage/Api2/Helper/Data.php
+++ b/app/code/core/Mage/Api2/Helper/Data.php
@@ -53,25 +53,23 @@ protected static function _compareOrder($a, $b)
      */
     public function getAuthAdapters($enabledOnly = false)
     {
-        $adapters = Mage::getConfig()->getNode(self::XML_PATH_AUTH_ADAPTERS);
+        $adapters = Mage::getConfig()?->getNode(self::XML_PATH_AUTH_ADAPTERS);
 
-        if (!$adapters) {
+        if (!$adapters instanceof Varien_Simplexml_Element) {
             return [];
         }
 
         $adapters = $adapters->asArray();
 
-        if ($enabledOnly) {
-            foreach ($adapters as $adapter) {
-                if (empty($adapter['enabled'])) {
-                    unset($adapters);
-                }
-            }
+        if (!is_array($adapters)) {
+            return [];
+        }
 
-            $adapters = (array) $adapters;
+        if ($enabledOnly) {
+            $adapters = array_filter($adapters, fn($adapter) => !empty($adapter['enabled']));
         }
 
-        uasort($adapters, ['Mage_Api2_Helper_Data', '_compareOrder']);
+        uasort($adapters, self::_compareOrder(...));
 
         return $adapters;
     }
@@ -83,14 +81,22 @@ public function getAuthAdapters($enabledOnly = false)
      */
     public function getUserTypes()
     {
-        $userModels = [];
-        $types = Mage::getConfig()->getNode(self::XML_PATH_USER_TYPES);
+        $types = Mage::getConfig()?->getNode(self::XML_PATH_USER_TYPES);
+
+        if (!$types instanceof Varien_Simplexml_Element) {
+            return [];
+        }
 
-        if ($types) {
-            foreach ($types->asArray() as $type => $params) {
-                if (!empty($params['allowed'])) {
-                    $userModels[$type] = $params['model'];
-                }
+        $types = $types->asArray();
+
+        if (!is_array($types)) {
+            return [];
+        }
+
+        $userModels = [];
+        foreach ($types as $type => $params) {
+            if (!empty($params['allowed'])) {
+                $userModels[$type] = $params['model'];
             }
         }
 
@@ -125,7 +131,7 @@ public function getResponseRenderAdapters()
      */
     public function isApiTypeSupported($type)
     {
-        return in_array($type, Mage_Api2_Model_Server::getApiTypes());
+        return in_array($type, Mage_Api2_Model_Server::getApiTypes(), true);
     }
 
     /**
diff --git a/app/code/core/Mage/Api2/Model/Resource/Acl/Filter/Attribute.php b/app/code/core/Mage/Api2/Model/Resource/Acl/Filter/Attribute.php
index b0b3de73f5f..514c32d7dab 100644
--- a/app/code/core/Mage/Api2/Model/Resource/Acl/Filter/Attribute.php
+++ b/app/code/core/Mage/Api2/Model/Resource/Acl/Filter/Attribute.php
@@ -31,7 +31,7 @@ protected function _construct()
      * @param  string                                          $userType
      * @param  string                                          $resourceId
      * @param  Mage_Api2_Model_Resource::OPERATION_ATTRIBUTE_* $operation
-     * @return null|bool|string
+     * @return null|false|string
      */
     public function getAllowedAttributes($userType, $resourceId, $operation)
     {