I get a error while I try to delete puppet class from foreman interface.

ActiveRecord::StatementInvalid
Mysql2::Error: Cannot delete or update a parent row: a foreign key constraint fails (`foreman`.`environment_classes`, CONSTRAINT `environment_classes_puppetclass_id_fk` FOREIGN KEY (`puppetclass_id`) REFERENCES `puppetclasses` (`id`)): DELETE FROM `puppetclasses` WHERE `puppetclasses`.`id` = 86
app/controllers/puppetclasses_controller.rb:40:in `destroy'
app/models/concerns/foreman/thread_session.rb:33:in `clear_thread'
lib/middleware/catch_json_parse_errors.rb:9:in `call'