Fatal error: Uncaught Error: Class "yii\db\Migration" not found in /users/quirl/www/filemanager/spark/protected/humhub/modules/space/migrations/m160217_161220_addCanLeaveFlag.php:6 Stack trace: #0 {main} thrown in /users/quirl/www/filemanager/spark/protected/humhub/modules/space/migrations/m160217_161220_addCanLeaveFlag.php on line 6