Fatal error: Uncaught Error: Class "Drupal\Core\Form\ConfirmFormBase" not found in /home/fnbrshareacopy/public_html/modules/contrib/block_class/src/Form/BlockClassConfirmDeletionAttributeForm.php:14 Stack trace: #0 {main} thrown in /home/fnbrshareacopy/public_html/modules/contrib/block_class/src/Form/BlockClassConfirmDeletionAttributeForm.php on line 14