Microsoft 365 Alert – Service Degradation – Exchange Online – Some users may see unwanted add-ins appearing automatically across all Outlook clients – ONGOING

12/08/2026 09:12:00 AM

NHS.net Connect Reference: INC46907040

Microsoft Reference: EX1441488

Issue Status: ONGOING

Issue Description: Some users may see unwanted add-ins appearing automatically across all Outlook clients.

More info: These add-ins are configured to be available to users by admins but aren’t expected to be automatically installed. To bypass this issue, admins can run the “Set-App -Identity -OrganizationApp -PrivateCatalog -DefaultStateForUser Disabled” command to remove add-ins that are unintentionally appearing.

Current Update: 09/09/2026 08:44:00 AM – Microsoft has verified with a subset of affected users that performing the identified workaround successfully mitigates the impact. They are preparing a permanent fix for deployment, which we expect will take several weeks to saturate. They will provide a resolution timeline once available.

Scope of impact: Impact may occur for some users that may see unwanted add-ins appearing automatically across all Outlook clients. This section may be updated as the investigation progresses.

Root cause: A portion of the Exchange Online add-in sync pipeline isn’t processing add-in state information as expected. This is causing incorrect EnabledStatus values being returned and Outlook automatically displaying add-ins configured as Available, which is resulting in impact.

Next update by: Friday, September 11, 2026, at 6:30 PM UTC