Outlook 365 not syncing with gmail

Question

Both my Gmail accounts have stopped syncing with Outlook 365 after the last update.

---

Moved from Microsoft 365 and Office | Other

Answer 1

This issue has been widely reported, and Microsoft is currently working on a fix and plan to release the patch as soon as possible.

In the meantime, if you are experiencing this issue with Outlook Classic, try accessing your Gmail account using the web browser version of Outlook.

Also, until a patch is released for the Outlook Gmail account issue, please check out the solutions provided by Microsoft via this link.

https://support.microsoft.com/en-us/office/users-get-errors-0x800ccc0e-0x800ccc0f-synchronizing-gmail-and-yahoo-accounts-in-classic-outlook-e5a7b684-7c5c-4848-ab2d-d48291451f67

Answer 2

Gmail sync failures in Outlook 365 after recent updates match known issues with Google account sign-in and permissions in classic Outlook. Resolution depends on updating Outlook to a fixed build and then redoing the Google consent so Outlook has full access to the Gmail mailbox.

Use the following detailed steps end to end:

1. Confirm Outlook build and update to a fixed version
2. In classic Outlook, select File > Office Account.
3. Check the version/build under About Outlook.
4. Ensure the build is at or above the fixed versions:
   • For the sign-in flow fix (separate browser window, resolves “app not secure” / IMAP setup errors):
     • Version 2404 (Build 17531.10000) or later in:
       • Beta Channel
       • Current Channel Preview
       • Current Channel
       • Monthly Enterprise Channel (Version 2407 Build 17727.10000 or later)
   • For the Gmail-permissions/sync fix in classic Outlook:
     • Current Channel Version 2412 Build 18324.20168 or later.
5. If the build is older, select Update Options > Update Now and let Office update fully, then restart Outlook.

If Outlook is not on at least these builds, Gmail sign-in and sync issues may persist regardless of other changes.

2. Re-run Google sign-in and grant full Gmail permissions

A common cause of Gmail accounts suddenly not syncing in classic Outlook is that the required Gmail permission was not granted (or was invalidated) during the browser sign-in.

When adding or re-authenticating Gmail in Outlook, the Google consent screen must include this permission:

“Read, compose, send, and permanently delete all your email from Gmail.”

If this box was not checked, Outlook cannot sync mail correctly and may show errors such as:

• “We couldn't log on to the incoming (POP/IMAP) server. Please check your email address and password and try again.”
• “We weren’t able to set up your Google account with IMAP. You may need to make changes to your Gmail settings.”
• Send/Receive error 0x800CCC0E for Gmail accounts.

After updating to Current Channel Version 2412 Build 18324.20168 or later, use the built-in retry flow:

1. Trigger a Send/Receive or wait for the sync error dialog for the Gmail account.
2. In the error window, select the Retry link.
3. Outlook will open a browser window to Google sign-in.
4. Sign in to the Gmail account.
5. On the permissions screen, ensure the checkbox for:
   • “Read, compose, send, and permanently delete all your email from Gmail.” is selected.
6. Approve/Allow the requested access.
7. Return to Outlook and let it complete the connection.

This replays the OAuth consent with the correct scope so Outlook can sync the mailbox again.

If the Retry link is not available or does not work, use the manual workaround: remove the Gmail account from Outlook, then add it again and carefully grant the full permission when the browser opens.

3. Address IMAP / “app not secure” errors when adding Gmail

If adding the Gmail account fails with messages like:

• “The browser or app may not be secure.”
• “We weren’t able to set up your Google account with IMAP. You may need to make changes to your Gmail settings.”

then:

1. Confirm Outlook is on a build that includes the updated sign-in flow (separate browser window) – Version 2404 (Build 17531.10000) or later on the supported channels listed above.
2. Try adding the Gmail account again from File > Account Settings > Account Settings > New.
3. When Outlook opens the browser to Google, complete sign-in and ensure the full Gmail permission is granted as described above.
4. For accounts where Google still exposes the IMAP toggle in Gmail settings, verify IMAP is enabled as described in Google’s “Add Gmail to another email client” help.

The updated Outlook builds use a more secure browser-based OAuth flow that resolves the “app not secure” error and IMAP setup failures.

4. If Gmail accounts were working and suddenly stopped after an update

For existing Gmail accounts that had been working for years and then stopped syncing after a recent Office update:

1. Update Outlook to at least Current Channel Version 2412 Build 18324.20168.
2. Trigger Send/Receive and look for an error dialog for the Gmail account.
3. Use the Retry link (if present) to re-run the Google sign-in and grant the full Gmail permission.
4. If the Retry option is not available or does not resolve the issue:
   • Remove the Gmail account from Outlook.
   • Add the Gmail account again so the new OAuth flow and permissions are applied cleanly.

If error 0x800CCC0E appears (“cannot connect to the server” when synchronizing subscribed folders), this is also consistent with missing/incorrect Gmail permissions and should be resolved by the steps above on a fixed build.

5. If an Insider channel was used as a temporary workaround

Some users temporarily switched Outlook to an Insider channel to get an early fix. Once the fix is in the regular Current Channel, switching back is recommended:

1. Use the registry-based method described in:
   • “Switching between Microsoft 365 Apps for Business/Enterprise, Current, Preview and Beta Channel (Office Insider) without re-installing” (Method 2: InsidersLabBehavior).
   • Or use the registry command approach in “Use a registry command to install Microsoft 365 Insider on Windows devices.”
2. After changing the channel, restart Outlook.
3. Go to File > Office Account > Update Options > Update Now to ensure the Current Channel build is fully updated.
4. Then follow the sign-in/permission steps above for each Gmail account.

Following these steps—update Outlook to a fixed build, re-run Google sign-in via Retry or re-adding the account, and explicitly granting the full Gmail permission—restores syncing for Gmail accounts in classic Outlook after the recent changes.

---

References:

• Unable to sign in or add a Gmail account to classic Outlook
• Unable to add a Gmail account to classic Outlook