Fatal error: Uncaught Error: Class "yii\bootstrap\Alert" not found in /var/www/html/prod/vendor/kartik-v/yii2-widget-alert/src/Bs3Alert.php:21 Stack trace: #0 {main} thrown in /var/www/html/prod/vendor/kartik-v/yii2-widget-alert/src/Bs3Alert.php on line 21