Adding a Gmail account to Outlook should be simple, but many users run into a frustrating roadblock. When trying to connect, Outlook sometimes throws this error:
“We couldn't log on to the incoming (POP/IMAP) server. Please check your email address and password and try again.”
If this looks familiar, you’re not alone. Users on Microsoft Tech Community have reported the same issue. Fortunately, the fix is often straightforward once you understand the causes.
Why Does This Outlook–Gmail Error Happen?
Several factors can trigger the IMAP login failure in Outlook:
- OAuth permissions not granted
Gmail requires Outlook to request full access to your mailbox. If you don’t approve this during setup, Outlook will fail to connect. - Cached or corrupted credentials
Old OAuth tokens stored in Windows Credential Manager can block new logins. - Google Passkeys interference
Recently added passkeys sometimes disrupt Outlook’s ability to authenticate. - Outdated Outlook version
Classic Outlook may not fully support the latest Gmail OAuth requirements. - Multiple Gmail sessions in browser
Having several accounts logged in during setup can confuse the authentication process.
How to Fix the Gmail IMAP Login Error in Outlook
1. Retry With Correct Permissions
If you’re on Outlook version 2412 Build 18324.20168 or later, click Retry when the error appears. A browser window will open—be sure to allow full Gmail access:
“Read, compose, send, and permanently delete all your email from Gmail.”
2. Revoke & Re-Authorize Access
- Go to your Google Account → Security → Third-party apps
- Remove “Microsoft apps & services”
- Re-add your Gmail account in Outlook and accept the full permissions request
3. Clear Cached Credentials
- Open Windows Credential Manager
- Delete entries starting with
MicrosoftOffice16_Data:OAUTH2 - Restart Outlook and retry setup
4. Remove Registry Keys (Advanced)
If problems persist, delete related keys under:
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities
Look for entries like tp_google_imap_OAuth2.
5. Disable Google Passkeys
Some users found removing recently added Passkeys in their Google Account instantly fixed the issue.
Quick Fix Summary
| Problem | Solution |
|---|---|
| Missing OAuth permissions | Retry and approve full Gmail access |
| Stale credentials in Windows | Delete via Credential Manager |
| Outlook blocked by Google Passkeys | Remove Passkeys from your Google account |
| Old Outlook version | Update or switch to the new Outlook app |
| Browser confusion with multiple logins | Sign out of other Gmail accounts during setup |
Final Thoughts
If Outlook won’t connect your Gmail account and you see the error “We couldn’t log on to the incoming (POP/IMAP) server,” don’t panic. In most cases, clearing cached credentials and re-authorizing Outlook with the right permissions will solve the problem.
Still stuck? Consider updating to the new Outlook for Windows, which offers better Gmail integration and fewer authentication headaches.
👉 Pro tip: Always make sure 2FA (two-factor authentication) is enabled on your Gmail account, and use OAuth instead of manually entering server settings for the most secure connection.
