Microsoft 365 outage: what happened and why services were affected

Microsoft has reported widespread disruption to Microsoft 365, affecting services including Outlook, Teams and Copilot. The incident began on Thursday 12 November, with Microsoft confirming that users in any region could experience connectivity problems.

What caused the disruption?

Microsoft initially reported “elevated load” on part of its infrastructure. It later clarified that this was not caused by an increase in traffic. A number of servers had unexpectedly become unavailable, leaving the remaining systems to handle more work.

A subsequent update identified a configuration issue that was causing servers to fail automated health checks and become unavailable.

These checks are normally used to identify servers that should not receive traffic. When servers are taken out of service, requests must be handled by the capacity that remains. In this incident, Microsoft said the loss of available servers was putting that infrastructure under strain.

Which services were affected?

Users reported problems with Outlook, Teams and Copilot, although the disruption did not affect every user or feature equally.

This can make an incident difficult to identify from an individual business’s perspective. Some staff may retain access while colleagues experience errors, and an application may open even though particular functions are unavailable.

What was Microsoft doing to restore service?

Microsoft’s published updates described restarting affected servers and testing a configuration change intended to address the failed health checks.

Those updates explain the immediate problem, but they are not a complete account of the underlying cause. A fuller explanation would need to establish what introduced the configuration issue, why it affected so many servers and how a recurrence will be prevented.

What does this mean for users?

Problems caused by a provider-side incident will not generally be resolved by reinstalling applications or changing settings on an otherwise working local network.

During an outage, Microsoft’s service-health updates are the starting point for checking the known impact and recovery progress. Microsoft 365 administrators can also consult their organisation’s service-health dashboard for more specific information, where it remains accessible.

For the latest updates, see Microsoft’s service-health status page.

Status at the time of publication, 13 November 2026: Microsoft’s public service-health page reports degradation affecting Microsoft 365. The recovery position may change as work continues.

Sources: Microsoft service health · BBC reporting