Microsoft 365 Alert – Service Degradation – Microsoft Teams – Some guest users may be unable to unmute their mics in recurring Microsoft Teams meetings when recording is enabled – NEW

18/12/2025 09:05:00 AM

NHSmail Reference: INC46708300

Microsoft Reference: TM1198582

Issue Status: OPEN

Issue Description: Some guest users may be unable to unmute their mics in recurring Microsoft Teams meetings when recording is enabled.

More info: This issue is specific to guest users who have joined Microsoft Teams meetings through the Windows or Mac desktop clients. This issue also impacts guest users when attempting to share their screen or turn on their camera during affected Microsoft Teams meetings. As a workaround, affected guest users can clear their cache to remove expired authentication components or utilize the Microsoft Teams web app or mobile app.

Current Update: 18/12/2025 09:05:00 AM – Microsoft have developed the fix to address the issue on the Teams desktop client for Mac and are preparing for its deployment to the affected environment. The deployment of the fix is expected to complete in early February 2026. They will continue monitoring the progress and will provide updates on the status as they become available.

Scope of impact: Some external guest participants attempting to unmute their microphones, share their screen, or use their camera during recurring Microsoft Teams meetings while recording may be impacted. This information may be updated as our investigation continues.

Root cause: The impact is the result of an issue affecting the authentication components assigned to guest users when joining recurring Microsoft Teams meetings and recording the meeting in which stale components are being leveraged and causing an error to occur that prevents these guest users from unmuting their mics, sharing their screen, or using their camera.

Next update by: Tuesday, January 6, 2026, at 3:30 AM UTC