Fatal error: Uncaught Error: Interface "Psr\EventDispatcher\EventDispatcherInterface" not found in C:\WebServer\htdocs\bookshelf\vendor\symfony\event-dispatcher-contracts\EventDispatcherInterface.php:19 Stack trace: #0 {main} thrown in C:\WebServer\htdocs\bookshelf\vendor\symfony\event-dispatcher-contracts\EventDispatcherInterface.php on line 19