Fatal error: Uncaught Error: Class 'Symfony\Component\HttpKernel\Event\RequestEvent' not found in /mnt/volume_lon1_01/backend/admin/vendor/symfony/http-kernel/Event/ExceptionEvent.php:30 Stack trace: #0 {main} thrown in /mnt/volume_lon1_01/backend/admin/vendor/symfony/http-kernel/Event/ExceptionEvent.php on line 30