Fatal error: Uncaught Error: Class "yii\base\Model" not found in /users/quirl/www/filemanager/spark/protected/humhub/modules/installer/forms/UseCaseForm.php:19 Stack trace: #0 {main} thrown in /users/quirl/www/filemanager/spark/protected/humhub/modules/installer/forms/UseCaseForm.php on line 19