Fatal error: Uncaught Error: Class 'Symfony\Contracts\EventDispatcher\Event' not found in D:\xampp\htdocs\psp\backend\vendor\symfony\http-kernel\Event\KernelEvent.php:23 Stack trace: #0 {main} thrown in D:\xampp\htdocs\psp\backend\vendor\symfony\http-kernel\Event\KernelEvent.php on line 23