Fatal error: Uncaught Error: Class "Symfony\Component\DependencyInjection\Extension\Extension" not found in C:\WebServer\htdocs\bookshelf\vendor\symfony\http-kernel\DependencyInjection\Extension.php:23 Stack trace: #0 {main} thrown in C:\WebServer\htdocs\bookshelf\vendor\symfony\http-kernel\DependencyInjection\Extension.php on line 23