Microsoft 365 Alert – Service Degradation – Exchange Online – Some users’ Exchange Online shared calendars may be out of sync – RESOLVED

Announcements Sourav Nandi

19/02/2025 08:44:00 AM

NHSmail Reference: INC46455496

Microsoft Reference: EX1010087

Issue Status: RESOLVED

Issue Description: Some users’ Exchange Online shared calendars may be out of sync.

More info: Users’ Exchange Online shared calendars between principal and delegates may be out of sync.

Final Update: 21/02/2025 08:45:00 AM – After monitoring and reviewing Microsoft’s service telemetry, they’ve confirmed that their deployment successfully completed its release and impact has been remediated.

Scope of impact: Some users serviced by the affected infrastructure whose shared calendars are out of sync may be impacted by this event.

Root cause: An impacting traffic management configuration change to the Calendar Replication service, which is responsible for facilitating the sync process between the principal and delegate calendars, is leading to impact.

Next steps: Microsoft are reviewing their metrics for testing and validating their changes to help identify areas of improvement and to prevent similar issues from occurring in the future.