Microsoft 365 Alert – Service Degradation – Microsoft Teams – Users may be unable to join town halls in Microsoft Teams using iOS 26.5 version and get an error message – RESOLVED

Announcements Shagufta Naaz

21/05/2026 08:30:00 AM

NHSmail Reference: INC46832370

Microsoft Reference: TM1317239

Issue Status: RESOLVED

Issue Description: Users may be unable to join town halls in Microsoft Teams using iOS 26.5 version and get an error message.

Final Update: 25/05/2026 09:59:00 AM – The fix deployment completed and after a period of monitoring, Microsoft confirmed impact is remediated.

Scope of impact: Some admins relying on security telemetry reporting in Microsoft Defender for Endpoint may be impacted. This information may be updated as our investigation continues.

Root cause: Any user attempting to join town halls in Microsoft Teams using iOS 26.5 version may be affected by this issue. This section may be updated as our investigation continues.

Next Steps: Microsoft are further working with the third-party service to understand how this update caused impact.