Microsoft 365 Alert – Service Degradation – Exchange Online – Some users may be unable to use Microsoft Outlook Classic while the Microsoft Teams Meeting Add-in is enabled- RESOLVED

Announcements Shagufta Naaz

17/03/2026 09:14:00 AM

NHSmail Reference: INC46775188

Microsoft Reference: EX1254044

Issue Status: RESOLVED

Issue Description: Some users may be unable to use Microsoft Outlook Classic while the Microsoft Teams Meeting Add-in is enabled.

More info: If Teams Meeting Add-in is disabled then Outlook Classic functions as normal.

As a workaround, users can also perform an Online Repair of Office or update Outlook to the latest version to resolve the issue.

Final Update: 08/05/2026 08:54:00 AM –Microsoft has confirmed that the fix has been successfully deployed and issue has been mitigated.

Scope of impact: Users attempting to use Microsoft Outlook Classic while the Microsoft Teams Meeting Add-in and previous Outlook build version is enabled may be impacted.

Root cause: A previous Outlook build version that is enabled is causing impact to occur.

Next Steps: Microsoft are reviewing their update procedures to better identify similar issues during our development and testing cycles.