Fatal error: Uncaught Error: Class "Symfony\Contracts\EventDispatcher\Event" not found in /media/jean/learning/huagai/drupal/vendor/symfony/http-kernel/Event/KernelEvent.php:23 Stack trace: #0 {main} thrown in /media/jean/learning/huagai/drupal/vendor/symfony/http-kernel/Event/KernelEvent.php on line 23