Fatal error: Uncaught Error: Class "yii\validators\FileValidator" not found in /users/quirl/www/filemanager/spark/protected/humhub/modules/file/validators/ImageSquareValidator.php:19 Stack trace: #0 {main} thrown in /users/quirl/www/filemanager/spark/protected/humhub/modules/file/validators/ImageSquareValidator.php on line 19