Microsoft 365 Alert – Service Degradation – Microsoft 365 suite,Microsoft Copilot (Microsoft 365) – Users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page – ONGOING

18/03/2026 09:09:00 AM

NHSmail Reference: INC46775778

Microsoft Reference: MO1254319

Issue Status: ONGOING

Issue Description: Users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page.

More info: The impact to Office.com is still occurring, but the impact to Microsoft 365 Copilot web clients, office.com/chat, m365.cloud.microsoft, m365.cloud.microsoft/chat and copilot.cloud.microsoft, have recovered as of March 17, 2026, at 4:05 PM UTC.

Users can access Microsoft Copilot through application-based Microsoft Copilot services. This includes, but is not limited to:
– Microsoft Copilot desktop app
– Copilot in Microsoft Teams
– Copilot in Office apps
User may be able to leverage https://m365.cloud.microsoft/search, and should be able to sign in using this page. Once signed in, users can access Office.com.

Current Update: 18/03/2026 08:53:00 AM – While Microsoft’s telemetry indicates that the impact is largely remediated, they are continuing to monitor the environment as their traffic optimizations are nearing completion. They are proceeding with the monitoring process to ensure the service is stable and to determine whether any additional mitigative steps may be necessary to fully resolve this issue.

Scope of impact: Impact is specific to some users who are served through the affected infrastructure.

Root cause: The infrastructure that supports access to Office.com and the Microsoft 365 Copilot web sign-in page is receiving a high volume of traffic that inhibits the rate at which some users’ requests are being processed, preventing some users from accessing the service pages.

Next update by: Wednesday, March 18, 2026, at 3:00 PM UTC