Fatal error: Uncaught Error: Class 'yii\db\Migration' not found in /home/wittyly/public_html/live/hr-witty/migrations/m201105_024600_alter_cols_make_nullable_property_value_tbl.php:8 Stack trace: #0 {main} thrown in /home/wittyly/public_html/live/hr-witty/migrations/m201105_024600_alter_cols_make_nullable_property_value_tbl.php on line 8