Microsoft 365 Alert – Service Degradation – Exchange Online –Users may be unable to search in Outlook on the web or Outlook desktop client – RESOLVED

Announcements Arpan Das

01/04/2025 10:45:00 AM

NHSmail Reference: INC46492615

Microsoft Reference: EX1045703

Issue Status: RESOLVED

Issue Description: Users may be unable to search in Outlook on the web or Outlook desktop client

More info: Affected users may also be unable to access their Exchange Online mailbox via any connection method.

Final Update: 02/04/2025 08:51:00 AM – Microsoft have confirmed that the impacting change was successfully reversed, and they have verified through service telemetry that this has remediated the issue.

Scope of impact: Impact was specific to some users who were served or located through the affected infrastructure in Europe.

Root cause: A recent configuration update to a subset of service infrastructure that helps facilitate search in Outlook on the web and the Outlook desktop client caused a memory usage issue, which resulted in impact.

Next steps: Microsoft are reviewing their configuration update processes so they can better identify similar memory usage issues during their testing phase and avoid comparable impact in the future.