Fatal error: Uncaught Error: Class "yii\web\Controller" not found in /home2/yiikharazmisabt/public_html/yii2-app/frontend/controllers/SiteController.php:21 Stack trace: #0 {main} thrown in /home2/yiikharazmisabt/public_html/yii2-app/frontend/controllers/SiteController.php on line 21