Fatal error: Uncaught Error: Class 'Symfony\Component\Config\Loader\FileLoader' not found in /mnt/volume_lon1_01/backend/admin/vendor/symfony/routing/Loader/XmlFileLoader.php:28 Stack trace: #0 {main} thrown in /mnt/volume_lon1_01/backend/admin/vendor/symfony/routing/Loader/XmlFileLoader.php on line 28