Fatal error: Uncaught Error: Class 'Symfony\Component\EventDispatcher\Event' not found in E:\xampp\htdocs\www\key1\vendor\symfony\event-dispatcher\LegacyEventProxy.php:20 Stack trace: #0 {main} thrown in E:\xampp\htdocs\www\key1\vendor\symfony\event-dispatcher\LegacyEventProxy.php on line 20