Microsoft Outlook Classic not allowing me to readd an existing gmail email account

Question

Outlook suddenly stopped updating/syncing one of my Gmail accounts. I have other gmail accounts on the same laptop that are working fine. I deleted the email account that wasn't working and now Outlook is telling me they're unable to set up my Gmail account with IMAP.

Answer 1

Have a look at:

Users get errors 0x800CCC0E & 0x800CCC0F synchronizing Gmail and Yahoo accounts in classic Outlook

and try the Workaround.

Answer 2

Follow these steps to get the Gmail account working again in classic Outlook.

1. Confirm Outlook has the Gmail fix

• The error “We weren’t able to set up your Google account with IMAP. You may need to make changes to your Gmail settings.” is a known issue that has been fixed.
• Make sure Outlook is on a build that includes the fix:
  • Current Channel: Version 2404 (Build 17531.10000) or later
  • Monthly Enterprise Channel: Version 2407 (Build 17727.10000) or later
• In Outlook, go to File > Office Account > About Outlook to check the version.

2. Retry the Gmail sign‑in with correct permissions If Outlook shows an error dialog when adding the Gmail account and offers a Retry link:

• Select Retry.
• When the Google sign‑in page opens in the browser, sign in to the correct Gmail account.
• On the consent screen, make sure the option for:
  • “Read, compose, send, and permanently delete all your email from Gmail.” is checked under Select what Microsoft apps & services can access.
• Complete the sign‑in and let Outlook finish the setup.

3. If Retry does not work: use the manual workaround Because this account previously existed in Outlook, cached permissions or credentials may be blocking re‑add. Use the manual cleanup steps below, then add the account again.

Step 1 – Remove Microsoft Apps & Services access in Gmail

1. Close Outlook completely.
2. Sign in to the affected Google account at google.com.
3. Select the profile picture (top right) > 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. Find Microsoft apps & services has some access to your Google Account and select See Details.
7. Under Access you've given to Microsoft apps & services, select Remove all access.
8. Select Confirm.

Step 2 – Remove the stored Google IMAP credentials in Windows

1. From the Windows Start menu, search for Credential Manager and open it (on some systems, open Control Panel first, then Credential Manager).
2. Select Windows Credentials.
3. Under Generic Credentials, locate entries starting with MicrosoftOffice16_Data:OAUTH2.
4. Expand each one and hover over MicrosoftOffice16_Data:OAUTH2 until the full name shows tp_google_imap_Oauth2 – these are the Gmail IMAP credentials.
5. Select Remove for each MicrosoftOffice16_Data:OAUTH2 entry that corresponds to the affected Gmail account (there are typically two per Gmail account).
   • If needed, map specific credentials to identities using the registry path:
     • Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities

Step 3 – Add the Gmail account back to Outlook

1. Start Outlook (classic).
2. Go to File > Add Account.
3. Enter the Gmail address and continue.
4. When the Google sign‑in window opens in the browser, sign in and on the permissions screen ensure the Gmail access option is checked:
   • “Read, compose, send, and permanently delete all your email from Gmail.”
5. Complete the wizard and let Outlook sync.
6. If Outlook never prompts for a password If, when trying to add the Gmail account as IMAP manually, Outlook does not prompt for a password:
7. On the IMAP settings page, ensure Require logon using Secure Password Authentication (SPA) is unchecked.
8. If still not prompted:
   • Open Control Panel > Mail > Email Accounts….
   • On the Email tab, select New.
   • Enter name, Gmail address, and password in both password fields, then select Next and follow the prompts.

After these steps, the removed Gmail account should add successfully and resume syncing alongside the other Gmail accounts.

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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
• Troubleshoot Outlook email setup
• gmail accounts no longer working in outlook classic - Microsoft Q&A
• search for solutions another user has found - Microsoft Q&A