Microsoft 365 Alert – Service Degradation – Exchange Online – Users may intermittently be unable to update or cancel calendar items in Outlook Win32 desktop client – RESOLVED

11/06/2024 08:53:00 AM

NHSmail Reference: INC43615917

Microsoft Reference: EX800425

Issue Status: RESOLVED

Issue Description: Users may intermittently be unable to update or cancel calendar items in Outlook Win32 desktop client.

More info: Users intermittently receive an error when updating or canceling calendar items that prevent these users from completing the intended action.

As a potential workaround, users can try updating meetings using the new Outlook desktop client or Outlook on the web: https://outlook.office365.com/calendar/view/day

Additional information on the end user experience and error messages being received can be found here: https://support.microsoft.com/en-us/office/outlook-shows-conflict-errors-when-updating-or-cancelling-meetings-69c26227-40ef-4377-8f12-1749fcaad2ad

Final Update: 17/07/2024 08:42:00 AM –  After an extended period of monitoring, Microsoft have determined that impact has been mitigated. They’ll continue to closely observe the health of the service to ensure ongoing stability as they evaluate the underlying causes of impact.

Additionally, the investigation into the root cause of the issue remains ongoing and more information will be shared once it is confirmed. They will continue to evaluate progress of the fix and provide an update on status in their next communication.

Scope of impact: This event can impact users updating or canceling calendar items in the Outlook desktop client.

Root Cause: Processing operations by backend systems that manage non-user changes to items exposed a problem with the handling of a given item”s version history. This error prevented the items from correctly synchronizing to Outlook (classic), resulting in end-user impact. The underlying cause of this behavior remains under investigation.