gmail stopped working in outlook overnight

Hello

Did you recently change your gmail password, if so, this is a known issue. Microsoft is still investigating this issue. The current workaround is published here: https://support.microsoft.com/office/users-get-errors-0x800ccc0e-0x800ccc0f-synchronizing-gmail-and-yahoo-accounts-in-classic-outlook-e5a7b684-7c5c-4848-ab2d-d48291451f67

Gmail connectivity issues in classic Outlook around that time are typically caused by changes in Google authentication and how Outlook is authorized to access Gmail.

For Office 2019 / classic Outlook, use these steps that match the documented Gmail/Outlook issues:

1. Verify IMAP is enabled in Gmail
   • Sign in to Gmail in a browser.
   • Go to Settings > See all settings > Forwarding and POP/IMAP.
   • Under IMAP access, make sure Enable IMAP is selected.
   • Select Save Changes.
2. Re‑authorize Outlook’s access to Gmail
   • Remove the affected Gmail account from Outlook.
   • Add the Gmail account again.
   • When the Google sign‑in window appears, sign in with the Gmail address and password.
   • On the Microsoft apps & services consent screen, ensure the permission for:

     Read, compose, send, and permanently delete all your email from Gmail. is checked/allowed.

   • Complete the sign‑in and finish the account setup.
   If Outlook shows errors like failing to log on to the IMAP server or cannot synchronize folders, this missing consent is a known cause and re‑doing the browser sign‑in with that permission enabled resolves it on supported builds.
3. If Outlook shows “Sorry, we could not sign you in to Google – IMAP”
   • Make sure Office is updated to a build where this issue is fixed (for similar issues, fixes were delivered via Office updates).
   • As a workaround on affected builds, enable optional connected experiences:
     • In Outlook, select File > Office Account.
     • Under Account Privacy, choose Manage Settings.
     • Check Enable optional connected experiences.
     • Restart Outlook and add the Gmail account again.
4. Confirm server settings if using manual setup
   • Incoming (IMAP) server: imap.gmail.com, SSL required, port 993.
   • Outgoing (SMTP) server: smtp.gmail.com, SSL/TLS required, authentication required, port 465 (SSL) or 587 (TLS/STARTTLS).

If the problem started overnight with no local changes, it is very likely related to updated authentication requirements between Google and Outlook; re‑enabling IMAP in Gmail and re‑authorizing Outlook with the full Gmail permission scope usually restores connectivity.

References:

• Unable to add a Gmail account to classic Outlook
• Unable to add a Gmail account to Outlook "Could not sign you in to Google"
• Fix problems connecting your Google account to the Microsoft Cloud
• gmail accounts no longer working in outlook classic - Microsoft Q&A