Via: T342903: LogicException: Domain '' is not recognized. and T343876: loginwiki: Failed creating job (MassMessageJob) from description we're noticing that some of the preferences for subscribers contains invalid data that will result in failure in delivery of notification.

We want to build a script that will identify this invalid data and fix it, if possible and then notify the subscribers that their preferences have been removed / updated.

To start with this script should verify that users do not have an empty wiki id as the target wiki to deliver the notification to.