Microsoft 365 Alert – Service Degradation – Exchange Online – Some users may have been unable to access the Microsoft To Do web application – RESOLVED

15/05/2026 08:50:00 AM

NHSmail Reference: INC46826633

Microsoft Reference: EX1310303

Issue Status: RESOLVED

Issue Description: Some users may have been unable to access the Microsoft To Do web application.

More info: While we are working to remediate the impact, admins can mitigate the issue by assigning the desired working hours and the time zone for the meeting rooms.

Final Update: 15/05/2026 08:50:00 AM – We determined that a transient configuration issue occurred, which caused the To Do app to fail to load. The issue was resolved after the affected infrastructure self‑recovered, and service is operating as expected.

Scope of impact: Your organization was affected by this event, and some users attempting to access the Microsoft To Do web application may have been impacted.

Root cause: A transient configuration issue occurred, causing users to lose access to the To Do web application.

Next update by: Microsoft are analyzing performance data and trends on the affected infrastructure to help prevent this problem from happening again.