symfony
diff --git a/‎src/Symfony/Component/Serializer/Normalizer/AbstractObjectNormalizer.php
+6-1 b/‎src/Symfony/Component/Serializer/Normalizer/AbstractObjectNormalizer.php
+6-1
diff --git a/‎src/Symfony/Component/Serializer/Tests/Normalizer/AbstractObjectNormalizerTest.php
+38 b/‎src/Symfony/Component/Serializer/Tests/Normalizer/AbstractObjectNormalizerTest.php
+38
@@ -32,6 +32,7 @@
 use Symfony\Component\Serializer\Mapping\ClassMetadataInterface;
 use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactoryInterface;
 use Symfony\Component\Serializer\NameConverter\NameConverterInterface;
+use Symfony\Component\TypeInfo\Exception\LogicException as TypeInfoLogicException;
 use Symfony\Component\TypeInfo\Type;
 use Symfony\Component\TypeInfo\Type\CollectionType;
 use Symfony\Component\TypeInfo\Type\IntersectionType;
@@ -702,7 +703,11 @@ private function validateAndDenormalize(Type $type, string $currentClass, string
                 }
 
                 if ($collectionValueType) {
-                    $collectionValueBaseType = $collectionValueType instanceof UnionType ? $collectionValueType->asNonNullable()->getBaseType() : $collectionValueType->getBaseType();
+                    try {
+                        $collectionValueBaseType = $collectionValueType->getBaseType();
+                    } catch (TypeInfoLogicException) {
+                        $collectionValueBaseType = Type::mixed();
+                    }
 
                     if ($collectionValueBaseType instanceof ObjectType) {
                         $typeIdentifier = TypeIdentifier::OBJECT;
 
@@ -1147,6 +1147,25 @@ public function testDenormalizeCollectionOfScalarTypesPropertyWithPhpDocExtracto
 
         $this->assertEquals($expected, $normalizer->denormalize($data, ScalarCollectionDocBlockDummy::class));
     }
+
+    public function testDenormalizeCollectionOfUnionTypesPropertyWithPhpDocExtractor()
+    {
+        $normalizer = new AbstractObjectNormalizerWithMetadataAndPhpDocExtractor();
+        $data = [
+            'values1' => [
+                'foo' => 'foo',
+                'bar' => 222,
+            ],
+            'values2' => [
+                'baz' => 'baz',
+                'qux' => 333,
+            ],
+        ];
+        $expected = new UnionCollectionDocBlockDummy($data['values1']);
+        $expected->values2 = $data['values2'];
+
+        $this->assertEquals($expected, $normalizer->denormalize($data, UnionCollectionDocBlockDummy::class));
+    }
 }
 
 class AbstractObjectNormalizerDummy extends AbstractObjectNormalizer
@@ -1577,6 +1596,22 @@ public function getValues(): ?array
     }
 }
 
+class UnionCollectionDocBlockDummy
+{
+    /**
+     * @param array<string, string|int> $values1
+     */
+    public function __construct(
+        public array $values1,
+    ) {
+    }
+
+    /**
+     * @var array<string, string|int>
+     */
+    public array $values2;
+}
+
 class AbstractObjectNormalizerWithMetadataAndPhpDocExtractor extends AbstractObjectNormalizer
 {
     public function __construct()
@@ -1596,6 +1631,9 @@ protected function getAttributeValue(object $object, string $attribute, ?string
 
     protected function setAttributeValue(object $object, string $attribute, mixed $value, ?string $format = null, array $context = []): void
     {
+        if (property_exists($object, $attribute)) {
+            $object->$attribute = $value;
+        }
     }
 
     public function getSupportedTypes(?string $format): array