Microsoft 365 Alert – Service Degradation – Exchange Online – Users may be unable to access the My Templates and Viva Insights add-ins in Exchange Online – ONGOING

Announcements Arpan Das

10/11/2025 09:38:00 AM

NHSmail Reference: INC46678913

Microsoft Reference: EX1183224

Issue Status: ONGOING

Issue Description: Users may be unable to access the My Templates and Viva Insights add-ins in Exchange Online.

Current Update: 04/12/2025 08:44:00 AM – Microsoft are continuing their review of the HAR logs to determine why their recent Admin API change reversion didn’t completely resolve this issue.

Scope of impact: The problem impacts some users trying to access the My Templates and Viva Insights Outlook add-ins in Exchange Online. This section may be updated as our investigation progresses.

Root cause: A recent change to the Admin API is causing a mismatch in the data format of users’ mailbox cache, and is resulting in the missing Outlook add-ins.

Next update by: Thursday, December 4, 2025, at 6:00 PM UTC