Some users may be unable to access apps in Microsoft 365 for the web

Affected services: Microsoft 365 for the web
Status: Service degradation
Issue type: Incident
User impact: Users may be unable to access apps in Microsoft 365 for the web.

More info:
Users may see the following message when viewing or accessing their Microsoft 365 apps using a web browser:

"We're experiencing a service outage. All of your open files have been saved. It may be some time before the outage is resolved."

As a workaround, users may be able to access their Microsoft 365 desktop applications and documents via the desktop applications.

Scope of impact: Impact is specific to some users, who are served through the affected infrastructure, attempting to access apps in Microsoft 365 for the web.

Microsoft issued the following at 1.10pm GMT - "We've disabled proactive caching to provide some relief. In parallel, we've tested and deployed a fix, which we believe will remediate impact. We anticipate that the fix will take approximately two hours to complete."

Microsoft have confirmed this issue is now resolved:

Root cause:
A recent service change inadvertently introduced an issue with identifying the token expiry time causing authentication requests to fail.

Next steps:
- We're reviewing our update procedures to better identify similar issues during our development and testing cycles.