Fatal error: Uncaught Error: Class "ApiPlatform\Serializer\AbstractItemNormalizer" not found in /var/www/html/API_Forum/vendor/api-platform/serializer/ItemNormalizer.php:37 Stack trace: #0 {main} thrown in /var/www/html/API_Forum/vendor/api-platform/serializer/ItemNormalizer.php on line 37