Microsoft 365 Alert – Service Degradation – Microsoft Teams – Some users may be unable to start a chat with a distribution group within Microsoft Teams – RESOLVED

12/06/2025 08:35:00 AM

NHSmail Reference: INC46553126

Microsoft Reference: TM1092645

Issue Status: RESOLVED

Issue Description: Some users may be unable to start a chat with a distribution group within Microsoft Teams.

Final Update: 13/06/2025 09:00:00 AM – The fix has completed deploying to the majority of the affected environments; however, the deployment to a specific portion of an affected environment failed. Microsoft have rerouted the remaining affected traffic to an alternate service infrastructure and have validated internally that impact is remediated.

Scope of impact: Some users who were attempting to start a chat with a distribution group within Microsoft Teams may have been affected.

Root cause: A recent change to how an API returns members of distribution lists was causing impact.

Next steps: Microsoft are implementing additional automated monitoring to assist in catching any potential impact before it occurs. In parallel, they’re also redeploying the fix to the failed portion of environment to ensure all affected environments receive the solution necessary to address the impacting change.