We have MS O365 in an appstack (App Volumes 2.15) and for some users whenever they open a MS Word attachment directly from Outlook i.e. then don't save it first they get the following error:
If you hit OK the Word document opens just fine, but the users are clearly irritated about getting this dialog every time they try to open a MS Word attachment from Outlook. Oddly this only happens with Word documents, other MS Office files like Excel open just fine and even more odd is that it only seem to happen for about half the users. This is definitely an issue with App Volumes though because I set up a test image with Office installed on the image and deployed to a pool and had one of the users where this happens to them use that pool and the error goes away. Everything else in the test pool was exactly the same except that for one MS Office is deployed via appstack and for the other it is installed directly on the image.
Anyone have any ideas as to what might be causing this?
Well I posted this and then spent a few hours looking into it and it turns out you need this registry key:
Hopefully if someone else see this issue this will help them.