Outlook sync errors with Gmail and IMAP

[wizpip]

Until last week, my Outlook had been syncing to a both a personal Gmail account, and a Gsuite email account via a Google domain for years.

Suddenly, last Tuesday night, I started getting errors on both accounts at the same time:

I thought this was strange, so I've done a number of things since then to try and fix it:

• Changed my Gmail app passwords on both accounts
• Turned IMAP off and on on both accounts
• Gone through the whole https://accounts.google.com/DisplayUnlockCaptcha thing
• Removed and reconfigured my accounts in Outlook
• Deleted my mail profile and recreated in Outlook
• Completely uninstalled office with the removal tool, and reinstalled it via web

About the last thing I haven't tried is reinstalling Windows.

When configuring the email accounts they do appear to be successful in the wizard:

And the email account DOES receive the Outlook test message. Outlook just then can't sync any of the folders.

On some occasions I get a strange new folder appear in the account on Outlook showing a more in depth sync error. Here's one example:

Now, I'm at a bit of a loss as to what to do next. As it happens, I also have a laptop with all the exact same configuration. I turned it on (for the first time since lockdown) and weirdly it managed to sync quite a lot even though I'd obviously deleted and changed app passwords (thank's Google!) I updated the laptop with the new app passwords, and everything works as expected.

So, I feel I'm left with one of the following:

• Somehow, Google has blocked my PC but not my laptop
• Outlook and / or the mail profile are damaged, and removing / reinstalling doesn't fix it (registry issues?)
• Windows 10 is causing it somehow

Any suggestions would be greatly appreciated! Now, remember I've only just turned the laptop on in 2 months so everything hasn't been updated in that long. Here are the version differences between my non-working PC and my working laptop.

PC:

Windows 10 1903 18362.778

Outlook 2004 12730.20270

Laptop:

Windows 10 1903 18362.535

Outlook 1911 12228.20364

Just updated Outlook to the same as on the PC - still works. I'll do the same with Windows and report back if Outlook stops working!

[#2]

Just to update on this, I have resolved my own issue.

I deleted my mail profile, uninstalled office, deleted all the credentials I'd used from Windows, deleted the Office folder entirely from AppData (Local & Roaming), then went through the registry and deleted anything that related to Office, and used CCleaner to clean it up afterwards.

Then I rebooted and reinstalled and finally everything works again. What was different this time was Outlook wasn't aware of my accounts at all, and the setup process was entirely different. No longer does it use App passwords, it just pops up a box from Google to authenticate. This seems like it may have been the issue, so I assume Gmail accounts set up with app passwords will fail in some Office updates until they are deleted from the Windows credential manager (or possibly more extreme doing as I did above).