Fatal error: Uncaught Error: Class "Symfony\Contracts\EventDispatcher\Event" not found in /home/qcsvlel/www/core/modules/package_manager/src/Event/SandboxEvent.php:13 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/modules/package_manager/src/Event/SandboxEvent.php on line 13