Can't Re Add Gmail after deletion in Outlook 2021

Question

I have a couple gmail accounts. One stopped working.

I tried fixing it in Outlook using File>Account Settings>Account Settings>Repair or Change

I kept getting an error to the effect that it couldn't connect to the server.

So I deleted the gmail account.

My other gmail accounts work just fine.

when I try to re-add the deleted gmail account, it actually shows up in the box to enter your email, but then after setting up using IMAP, it gives me an error:

We weren't able to setup your Google account with IMAP, you may need to make changes to your Gmail Settings.

I've checked my gmail settings by comparing to the working gmail accounts and all my IMAP settings are fine.

Seems like there is something in Outlook that did not get removed when i deleted the account, or something is corrupt.

Before I delete the profile and start over again, I thought I'd check to see if you could help.

Thanks much!

Answer 1

The deleted Gmail account likely still has cached OAuth/IMAP credentials and app access that block re‑adding it, even though other Gmail accounts work.

Follow this manual cleanup, then add the account again.

1. Remove Outlook’s access to that Gmail account
   1. Close Outlook.
   2. Sign in to the affected Google account at https://www.google.com.
   3. Select the profile picture → Manage your Google Account.
   4. In the left menu, select Security.
   5. Scroll to Your connections to third-party apps & services and select Microsoft apps & services.
   6. Under Access you've given to Microsoft apps & services, select See Details.
   7. Select Remove all access for Microsoft apps & services.
   8. Confirm.
2. Delete the stored Google IMAP credentials in Windows
   1. From the Start menu, search for Credential Manager and open it (on some systems via Control Panel → Credential Manager).
   2. Select Windows Credentials.
   3. Under Generic Credentials, find entries starting with MicrosoftOffice16_Data:OAUTH2.
   4. Expand each and hover over the name until the full value shows, including tp_google_imap_Oauth2. These are the Gmail IMAP credentials.
   5. Remove each credential that matches MicrosoftOffice16_Data:OAUTH2 for the affected Gmail account. There are typically two per Gmail account.
   6. If multiple Gmail accounts exist and only one should be removed, map credentials to identities using the registry path:
      • Open Registry Editor and paste: Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities
      • Use the identity subkeys to match the correct Gmail account before deleting only those credentials.
3. Re-add the Gmail account in Outlook
   1. Open Outlook.
   2. If the profile still shows a “Sign in via browser” bar for that Gmail account, use it and complete sign‑in in the browser, ensuring the checkbox for Microsoft apps & services is selected.
   3. If the account was fully removed, go to File → Add Account, enter the Gmail address, and complete the browser sign‑in, again allowing Microsoft apps & services.

If the issue persists and Outlook is not on a build that includes the Gmail sign‑in fixes, updating Outlook to a build listed in the Gmail sign‑in fix article may also be required.

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References:

• Unable to add a Gmail account to classic Outlook
• Unable to sign in or add a Gmail account to classic Outlook
• Unable to add a Gmail account to Outlook "Could not sign you in to Google"