Microsoft 365 Alert – Service Degradation – Microsoft Teams – Users with non-ANSI characters in their alias may be unable to launch the Microsoft Teams desktop client – ONGOING

Announcements Arpan Das

15/05/2026 02:23:00 PM

NHSmail Reference: INC46827776

Microsoft Reference: TM1311440

Issue Status: ONGOING

Issue Description: Some users with non-ANSI characters in their alias may be unable to launch the Microsoft Teams desktop client

More info: Affected users may be unable to launch the Microsoft Teams desktop client due to failures during character encoding conversion.

Current Update: 15/05/2026 08:45:00 AM –Microsoft has identified that a character encoding issue during Teams client start-up is causing failures for users with certain Unicode characters in their aliases. They are actively developing a fix and will validate it prior to deployment. They expect to provide estimated deployment timeline in our next scheduled update.

Scope of impact: Impact is specific to some users attempting to launch the Microsoft Teams desktop client.

Root cause: A character encoding issue during Teams client start-up is causing failures for users with certain Unicode characters in their aliases.

Next update by: Tuesday, May 19, 2026, at 2:00 PM UTC