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: 05/12/2025 08:19:00 AM – Microsoft are continuing their investigation of the HAR logs to determine why their previous fix didn’t remediate impact for all users as expected.

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: Friday, December 5, 2025, at 6:00 PM UTC