Apologies if this isn't the right place to ask this, but there are some very technical people here who might have an idea.
We have a W11 VDI estate with Office 365 (16.0 Click-to-run Monthly Channel) installed. At some point, about the 18th March, we started getting calls about a custom app crashing with the same error. Nothing before and every day since. It was mid-patching cycle so the images were untouched. No GPO or other policy changes. No part of the custom app has changed in years.
The app uses Office automation to do something similar to a mail-merge.
The weird thing is that despite all of the user config being the same and the same image for VDI, this may or may not happen for any user on any session. It is completely unpredictable.
The issue is largely caused by the old app as it's been largely the same going back to at least Word 2003 - I know it should be rewritten to be more robust, but that will take months to do and test and this is massively disruptive.
I've managed to narrow it down to Word users settings in HKCU\Software\Microsoft|Office\16.0\Word\Option. There are at least 3 problem values, but I've not narrowed the 3rd one down yet. The two that I have are:
ZoomApp=0 - changes itself to 1 and BulletproofOnCorruption=1 keeps being deleted. It doesn't matter if we're saving profiles or not. Again it is not consistent - if the profile isn't being saved a user may log on to an identical VDI session and get the issue and log off and on and not get it. Or some users may never get it.
Again, nothing internal has been changed. They are pretty trival settings and the users aren't changing them but it's screwing up Word Automation. The app is really sensitive to Word settings - for example changing the default view to Web View breaks it.
Is anyone aware of anything that was changed by Microsoft during that week? I know there was a change on the web versions that changed how pages are viewed roughly at the same time that caused a similar issue elsewhere. Anything that would affect the desktop versions?
I feel like I'm losing my mind.
(Yes, we have asked MS - the call was assigned to someone who knew Office Automation very well who confirmed stuff with our devs about how to make it more robust (again - multiple month delay if we go down that route) but got completely lost when I asked about the registry)