We have a problem in version 3.9.1 that we are very surprised no one reported yet.
The problem is this: after trying to enter a preview mode of a site via the Tag Manager’s container (e.g. ?mtmPreviewMode=J4iRd2NX etc.), we get an Angular’s “The controller with the name ‘MtmDebugController’ is not registered.” error.
We didn’t do anything to cause this …
A picture of the problem is attached.
Any help on this will be much appreciated.