diff --git a/src/Mapping/AssociationMapping.php b/src/Mapping/AssociationMapping.php
index 74bef09f9d..e5ef0ffcca 100644
--- a/src/Mapping/AssociationMapping.php
+++ b/src/Mapping/AssociationMapping.php
@@ -135,7 +135,13 @@ public static function fromMappingArray(array $mappingArray): static
                     continue;
                 }
 
-                assert($mapping instanceof ManyToManyOwningSideMapping);
+                if (! $mapping instanceof ManyToManyOwningSideMapping) {
+                    throw new MappingException(
+                        "Mapping error on field '" .
+                        $mapping->fieldName . "' in " . $mapping->sourceEntity .
+                        " : 'joinTable' can only be set on many-to-many owning side.",
+                    );
+                }
 
                 $mapping->joinTable = JoinTableMapping::fromMappingArray($value);
 
diff --git a/tests/Tests/ORM/Functional/InvalidMappingDefinitionTest.php b/tests/Tests/ORM/Functional/InvalidMappingDefinitionTest.php
new file mode 100644
index 0000000000..4a69070b3d
--- /dev/null
+++ b/tests/Tests/ORM/Functional/InvalidMappingDefinitionTest.php
@@ -0,0 +1,133 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\ORM\Functional;
+
+use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\Common\Collections\Collection;
+use Doctrine\ORM\Mapping as ORM;
+use Doctrine\ORM\Mapping\Entity;
+use Doctrine\ORM\Mapping\MappingException;
+use Doctrine\ORM\Mapping\Table;
+use Doctrine\Tests\OrmFunctionalTestCase;
+
+/**
+ * Functional tests for the Class Table Inheritance mapping strategy.
+ */
+class InvalidMappingDefinitionTest extends OrmFunctionalTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+    }
+
+    public function testManyToManyRelationWithJoinTableOnTheWrongSide(): void
+    {
+        $this->expectException(MappingException::class);
+        $this->expectExceptionMessage("Mapping error on field 'owners' in Doctrine\Tests\ORM\Functional\OwnedSideEntity : 'joinTable' can only be set on many-to-many owning side.");
+
+        $this->createSchemaForModels(
+            OwningSideEntity::class,
+            OwnedSideEntity::class,
+        );
+    }
+}
+
+#[Table(name: 'owning_side_entities1')]
+#[Entity]
+class OwningSideEntity
+{
+    #[ORM\Id]
+    #[ORM\GeneratedValue]
+    #[ORM\Column(type: 'integer')]
+    private int $id;
+
+    #[ORM\ManyToMany(targetEntity: OwnedSideEntity::class, inversedBy: 'owners')]
+    #[ORM\JoinTable(name: 'owning_owned')]
+    private Collection $relations;
+
+    public function __construct()
+    {
+        $this->relations = new ArrayCollection();
+    }
+
+    public function getId(): int
+    {
+        return $this->id;
+    }
+
+    public function getRelations(): Collection
+    {
+        return $this->relations;
+    }
+
+    public function addRelation(OwnedSideEntity $ownedSide): void
+    {
+        if (! $this->relations->contains($ownedSide)) {
+            $this->relations->add($ownedSide);
+            $ownedSide->addOwner($this);
+        }
+    }
+
+    public function removeRelation(OwnedSideEntity $ownedSide): void
+    {
+        if ($this->relations->removeElement($ownedSide)) {
+            $ownedSide->removeOwner($this);
+        }
+    }
+}
+
+#[Table(name: 'owned_side_entities1')]
+#[Entity]
+class OwnedSideEntity
+{
+    #[ORM\Id]
+    #[ORM\GeneratedValue]
+    #[ORM\Column(type: 'integer')]
+    private int $id;
+
+    #[ORM\Column(type: 'string', length: 255)]
+    private string $data;
+
+    #[ORM\ManyToMany(targetEntity: OwningSideEntity::class, mappedBy: 'relations')]
+    #[ORM\JoinTable(name: 'owning_owned')]
+    private Collection $owners;
+
+    public function __construct()
+    {
+        $this->owners = new ArrayCollection();
+    }
+
+    public function getId(): int
+    {
+        return $this->id;
+    }
+
+    public function getData(): string
+    {
+        return $this->data;
+    }
+
+    public function setData(string $data): void
+    {
+        $this->data = $data;
+    }
+
+    public function getOwners(): Collection
+    {
+        return $this->owners;
+    }
+
+    public function addOwner(OwningSideEntity $owningSide): void
+    {
+        if (! $this->owners->contains($owningSide)) {
+            $this->owners->add($owningSide);
+        }
+    }
+
+    public function removeOwner(OwningSideEntity $owningSide): void
+    {
+        $this->owners->removeElement($owningSide);
+    }
+}