Escalation Request – Classic Outlook 2019 Gmail OAuth failure – localhost:8011

Dear Microsoft Outlook Support Team,

I am requesting a technical investigation and escalation regarding a recurring Gmail authentication failure in Classic Outlook.

System information:

• Operating system: Windows 10 Pro, 64-bit

Application: Microsoft Outlook 2019 Home and Business

Version: 2508

Build: 16.0.19127.20936

Gmail account: Personal Google account

Error: 0x800CCC0E

OAuth callback error: localhost:8011 – ERR_CONNECTION_REFUSED

Additional Google error: 403 rate_limit_exceeded

Description of the problem:

My Gmail account stopped synchronizing in Classic Outlook without any changes to my settings.

Google authentication and consent sometimes complete successfully in Chrome, but Outlook fails to receive or process the OAuth callback.

The browser displays ERR_CONNECTION_REFUSED at localhost:8011.

My four other Outlook email accounts continue to work normally.

Troubleshooting already completed:

Verified Gmail connectivity to imap.gmail.com:993

Confirmed localhost resolves to 127.0.0.1 and ::1

Checked Windows Credential Manager and reset Gmail OAuth credentials

Reauthorized Microsoft apps & services in Google

Enabled Office Connected Experiences

Performed Microsoft Office Quick Repair

Verified antivirus and firewall operation

Tested account removal and reconfiguration

Attempted manual IMAP configuration with a Google app password

None of these procedures has resolved the recurring OAuth authentication failure.

Similar incidents have been reported in Microsoft Q&A, including reports of the OAuth listener on port 8011 closing before the browser callback is received.

I would appreciate a technical response to the following questions:

Is Microsoft investigating a possible OAuth callback listener defect affecting Classic Outlook?

Can Outlook prematurely close its local HTTP listener on port 8011 during Gmail authorization?

Are there diagnostic logs or tracing procedures available to determine why the callback fails?

Is there an official workaround or planned correction?

Can this case be escalated to the Outlook engineering team rather than repeating standard credential-reset instructions?

Please provide a case number and, if possible, a technical escalation.

Thank you for your assistance.

Kind regards,

Boštjan Bernik