A problem with Tag Manager's preview feature

Hi Everyone!

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.



Thanks for the report. Can you please create the issue directly in the issue tracker for tag manager here: Issues · matomo-org/tag-manager · GitHub
Then a developer will investigate


I will do that.

Thank you very much for replying!


See here (for anyone coming across this in the future):