Microsoft 365 Alert – Service Degradation – Exchange Online – Some users may be unable to access archive mailboxes in the Outlook desktop client – RESOLVED

Announcements Sourav Nandi

30/03/2023 17:45:00 PM (GMT)

NHSmail Reference : INC35076030

Microsoft Reference : EX534645

Issue Status : RESOLVED

Issue Description : Some users may be unable to access archive mailboxes in the Outlook desktop client.

More Info : Affected users may receive repeated credentials prompts when attempting to access archive mailboxes in the Outlook desktop client.

Final Update : 31/03/2023 09:10:00 AM – Deployment of the fix to revert the offending change is complete, and Microsoft’s service telemetry has confirmed that access to the affected mailboxes is restored and impact is remediated.

Root cause : A recent change to the configuration file for Autodiscover introduced a regression which resulted in the request filtering module incorrectly failing access requests as invalid with a 404 error

Next steps: Microsoft are reviewing their Exchange Online update procedures pertaining to Autodiscover configurations to prevent similar impact in future updates.