Forum Discussion
Gmail sync issues within Outlook Classic
Hi, there is a global security update that is changing the credentials for your Gmail account with Outlook Classic. You need to do two things: Here is the link on how to do it from the Microsoft site. I'd skip down to the manual fixes:
This process did not resolve the issue...
This process did not resolve the issue...
I have a writeup on this issue I call "Start From Scratch". Some people have found that this works when the quick workarounds from Microsoft Support don't.
See the answer by "Hornblower409 Mar 19, 2026, 12:37 AM" at
Pay particular attention to Step 1
Export any data for the GMail account that you have stored only locally in "This Computer Only" folders. Since the OST file it is stored in will be useless once you remove the account.
If that doesn't fix it for you, come back and we'll look for something else. After all, this is Outlook, there are lots of different ways it can go sideways that have nothing to do with cached OAuth credentials.