Microsoft explains cause of Microsoft 365, Outlook and Teams outage

Microsoft announced broad recovery and stability across its systems following an hours-long outage that began on some of its services on November 12. The company stated that the outage was caused by a technical issue unrelated to cyber activity or artificial intelligence (AI).

According to a statement from Microsoft on November 13, 2026, the issue originated during an earlier network capacity upgrade and surfaced following a recent network change. The company noted that the underlying issue has been resolved and work is ongoing for customers and regions whose services have not yet been restored.

Microsoft reported that services are being brought back online in phases due to the scale of demand. The company said system stability is verified at each stage, adding that while this approach extends the process, it helps ensure a stable restoration of services. The statement also expressed deep regret for the disruption caused to customers and partners, noting that user trust is taken seriously.

Businesses disrupted in more than 70 countries

Reports of access issues for services such as Microsoft 365, Outlook, and Teams began arriving on November 12. During the hours-long outage, users in more than 70 countries experienced problems, disrupting operations at companies and public institutions worldwide. Due to the disruptions in Outlook and Teams, users were unable to access their emails, manage their calendars, or hold online meetings.

In earlier statements during the outage, Microsoft reported that it had detected increased load in specific parts of its infrastructure across multiple regions, which may have led to connection errors. The company stated that the increased load stemmed from some servers unexpectedly going offline rather than high traffic volume, which added strain to the remaining infrastructure.

While work continues for regions that still lack access, Microsoft will publish a report on the outage after completing its investigation.