Microsoft 365 Alert – Service Degradation – Microsoft Teams – Users receiving cross-cloud chat messages may have seen unknown users in Microsoft Teams – RESOLVED

19/03/2026 09:25:00 AM

NHSmail Reference: INC46788746

Microsoft Reference: EX1233142

Issue Status: RESOLVED

Issue Description: Users receiving cross-cloud chat messages may have seen unknown users in Microsoft Teams.

Final Update: 02/04/2026 09:14:00 AM – Microsoft has identified that a recent standard service update, intended to prepare the service for a new feature to improve the experience for organizations that use cross-cloud chat messages, inadvertently contained a code regression that was resulting in impact. They have reverted the aforementioned update and confirmed impact is no longer occurring after a period of monitoring.

Scope of impact: Impact was specific to some users receiving messages through Microsoft Teams.

Root cause: A recent standard service update, intended to prepare the service for a new feature to improve the experience for organizations that use cross-cloud chat messages, inadvertently contained a code regression that was resulting in impact.

Next Steps: Microsoft are reviewing their recent standard service update procedures to help prevent similar impact from happening again.