Fatal error: Uncaught Error: Class 'yii\helpers\StringHelper' not found in D:\phpStudy\WWW\Soeasy\vendor\yiisoft\yii2-gii\src\generators\crud\default\controller.php:13 Stack trace: #0 {main} thrown in D:\phpStudy\WWW\Soeasy\vendor\yiisoft\yii2-gii\src\generators\crud\default\controller.php on line 13