Fatal error: Uncaught Error: Class "Drupal\Core\Config\Entity\ConfigEntityBase" not found in /home/www/drupal8/test/modules/migrate_plus/src/Entity/MigrationGroup.php:25 Stack trace: #0 {main} thrown in /home/www/drupal8/test/modules/migrate_plus/src/Entity/MigrationGroup.php on line 25