Microsoft 365 Alert – Service Degradation – Microsoft Teams – Users receive an error when launching the Microsoft Teams desktop client or web app – RESOLVED

Announcements Arpan Das

10/07/2025 08:32:00 AM

NHSmail Reference: INC46576221

Microsoft Reference: TM1112354

Issue Status: RESOLVED

Issue Description: Users receive an error when launching the Microsoft Teams desktop client or web app.

More info: When users launch the Microsoft Teams desktop client or web app, they may receive an error which states: “There was a problem reaching this app.”

The users may be able to click the apps on the left sidebar to bypass the error.

Final Update: 16/07/2025 09:00:00 AM – After a period of monitoring service health subsequent to the deployment of Microsoft’s fix to the impacted environment, Microsoft have confirmed from telemetry that this issue is no longer occurring.

Scope of impact: Any user attempting to launch the Microsoft Teams desktop client or web app may be impacted.

Root cause: A recent change, intended to improve the left sidebar, is enabling an unoptimized code flow which is resulting in impact

Next steps: Microsoft are reviewing their validation and updating procedures to better detect and prevent issues like this prior to deployment in the future.