Microsoft said on Saturday morning that it had fully restored its services after a major global outage that left millions of users across at least 74 countries unable to access email, messaging and workplace tools for more than a day.

The disruption began at around 6 p.m. GMT on Thursday, 12 November, knocking out Outlook, Microsoft Teams, the Copilot AI assistant and other Microsoft 365 services. Monitoring site Downdetector recorded more than 130,000 reports of Outlook problems in the United States at the peak on Thursday night, with Teams reports also surging in the UK from about 6.15 p.m.

The impact spread well beyond office workers. Police forces, the NHS, businesses, courts and schools were among those affected, and governments in several countries put contingency measures in place as email and messaging went down. Airline operations were also disrupted in some regions.

What went wrong

Microsoft said the outage was a technical failure and not a cyberattack. The company said servers responsible for establishing secure connections became overloaded and could no longer process user requests. The problem was introduced by an issue during an earlier network-capacity upgrade that surfaced following a recent network change, leaving the servers unable to cope with demand.

"We are deeply sorry for the disruption this incident has caused our customers and partners," Microsoft said in a statement on its Microsoft 365 status page, adding that it was seeing "broad recovery and stability across our services". The company said it would provide a full post-incident report once its review is complete.

Gradual recovery

Services were restored gradually rather than all at once. Most were back online by 3 p.m. Eastern Time on Friday, and by 2:50 p.m. that day Downdetector reports of Outlook problems had fallen to around 1,600 from the Thursday peak. Microsoft said it would keep monitoring the affected environment for an extended period, warning that some users might still see intermittent access problems or delayed email delivery while mail backlogs cleared.

The outage was one of the longest in Microsoft's history and the second disruption to its services this year. It also came in the same week as Friday's nationwide ground stop of US flights after a communications failure at air traffic control centres — a separate incident in which officials likewise ruled out a cyberattack.

For the millions who depend on Microsoft 365 for work, school and public services, the episode was a reminder of how much of daily life now runs through a handful of cloud platforms — and how quickly a single technical fault can bring it to a halt.