I got this error during a sequence campaign setup. See the mailwizz in this error:

Error 500!
CDbCommand failed to execute the SQL statement: SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`mailwizz`.`mw_campaign_template_url_action_subscriber`, CONSTRAINT `fk_campaign_template_url_action_subscriber_campaign_tem1` FOREIGN KEY (`template_id`) REFERENCES `mw_campaign_template` (`t)