Fatal error: Uncaught Error: Class "Symfony\Contracts\EventDispatcher\Event" not found in /home2/yiikharazmisabt/public_html/yii2-app/vendor/symfony/event-dispatcher/GenericEvent.php:23 Stack trace: #0 {main} thrown in /home2/yiikharazmisabt/public_html/yii2-app/vendor/symfony/event-dispatcher/GenericEvent.php on line 23