We had the exact same issue and solved it today.
Our database had what looked like an issue caused by not escaping “\” in a class column of the notificationview module (Upgrade Script???).
We had to get into the DB inside our docker. Follow the below to get SQL access.
Then run:
select * from module where module='notificationview';
If the “class” column has XiboWidgetNotificationView as its value, this is wrong. It needs to be Xibo\\Widget\\NotificationView.
To update the row enter:
update module set class='Xibo\\\\Widget\\\\NotificationView' where module='notificationview';
That should be it!