Fatal error: Uncaught Error: Class "ApiPlatform\Serializer\AbstractCollectionNormalizer" not found in /var/www/html/API_Forum/vendor/api-platform/hydra/Serializer/CollectionNormalizer.php:33 Stack trace: #0 {main} thrown in /var/www/html/API_Forum/vendor/api-platform/hydra/Serializer/CollectionNormalizer.php on line 33