Fatal error: Uncaught Error: Class 'Drupal\features_ui\Form\AssignmentFormBase' not found in /var/www/html/tmp/contrib/features/modules/features_ui/src/Form/AssignmentAlterForm.php:10 Stack trace: #0 {main} thrown in /var/www/html/tmp/contrib/features/modules/features_ui/src/Form/AssignmentAlterForm.php on line 10