Fatal error: Uncaught Error: Class 'Symfony\Component\Config\Loader\FileLoader' not found in /mnt/volume_lon1_01/backend/admin/vendor/symfony/routing/Loader/DirectoryLoader.php:18 Stack trace: #0 {main} thrown in /mnt/volume_lon1_01/backend/admin/vendor/symfony/routing/Loader/DirectoryLoader.php on line 18