Fatal error: Uncaught Error: Class 'yii\widgets\Pjax' not found in /opt/lampp/htdocs/123playnow-stage/vendor/execut/yii2-widget-bootstraptreeview/examples/example-pjax-navigation.php:6 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/123playnow-stage/vendor/execut/yii2-widget-bootstraptreeview/examples/example-pjax-navigation.php on line 6