Microsoft 365 Alert – Service Degradation – Microsoft Teams – Users get an error that can be bypassed when launching that Microsoft Teams desktop and web apps – RESOLVED

Announcements Arpan Das

08/08/2025 08:29:00 AM

NHSmail Reference: INC46600582

Microsoft Reference: TM1131505

Issue Status: RESOLVED

Issue Description: Users get an error that can be bypassed when launching that Microsoft Teams desktop and web apps.

More info: Affected users see an error that they couldn’t connect to this app.” when launching the Microsoft Teams desktop and web app. Users can bypass this error message and launch the app by clicking the “Activity” or “Chat” buttons on the left side of the screen.

Final Update: 27/08/2025 08:48:00 AM – Microsoft’s deployment of a fix to address the unoptimized code flow causing the error has completed, and after a period of monitoring service telemetry, they have validated that impact is resolved and users can launch the Microsoft Teams desktop and web apps without interruptions, as expected.

Scope of impact: Your organization is impacted by this event, and the problem impacts users launching the Microsoft Teams desktop and web apps.

Root cause: A recent change, intended to improve the left sidebar in Microsoft Teams, enabled an unoptimized code flow that’s causing an error to be generated when launching that Microsoft Teams desktop and web app.

Next Steps: Microsoft are analyzing the offending change to determine why the unoptimized code flow wasn’t discovered and addressed during our update testing and validation phases. These actions will allow them to improve and iterate upon their current validation procedures to ensure similar impact scenarios doesn’t occur in future and to improve the resilience and reliability of their future updates to Microsoft Teams.