Microsoft has fully restored its Microsoft 365 services after a global outage that lasted more than 36 hours, bringing Outlook, Teams and Copilot back online for users in more than 70 countries. The company confirmed early on Saturday 14 November that all affected services had recovered.
The disruption began on Thursday 12 November, when users first reported that they could not open their Exchange Online mailboxes. It soon spread to the services built around email, including Outlook, Teams, Copilot, SharePoint, Planner and To Do. Businesses, government agencies, schools and other organisations struggled to reach email, calendars, virtual meetings and cloud apps for two working days. Downdetector logged more than 7.4 million problem reports worldwide.
What caused the outage
Microsoft traced the fault to an earlier network capacity upgrade. The issue surfaced after a more recent network change, and several servers unexpectedly went offline after failing automated health checks. That created a cascading effect, putting extra pressure on the remaining servers and knocking out the services that depend on Exchange Online.
The company was clear about what it was not. In one update it said: “This was a technical issue not related to cyber or AI / agents.” It ruled out a cyberattack and said AI agents were not responsible. Microsoft paused all routine configuration updates, which an internal review had flagged as a possible trigger, and put in place an alternative health-check method alongside traffic restrictions to steady the network.
The outage is unconnected to Friday’s nationwide FAA ground stop in the United States, Homeland Security Secretary Markwayne Mullin said. It was one of the longest service breakdowns in Microsoft’s history.
How long it really lasted
The 36-hour figure counts from Microsoft’s first public acknowledgment, at about 9:54 a.m. Pacific time on Thursday, to its all-clear at about 1 a.m. Eastern time on Saturday. Microsoft’s own incident log puts the disruption at about 30 hours, using different start and end times, and records the end of impact at 9:40 p.m. India time on Friday 13 November. The company kept the incident open overnight while delayed email drained through the system.
Microsoft also extended its email timeout window to 48 hours so delayed mail kept retrying instead of bouncing back. Some delayed email may still have been arriving on Saturday afternoon as queues cleared. The company said it will publish a full post-incident review once its technical investigation concludes, but it has not yet said exactly which network change triggered the failure, how many organisations lost access, or what it will change to prevent a repeat.
What users should check now
Microsoft says people using Outlook, Teams and Copilot should no longer face disruption, but some delayed email was still arriving on Saturday as the queues cleared. Anyone still missing mail should check their spam and junk folders, and workplace admins can follow the Microsoft 365 admin centre service health page for updates.
The outage also hit third-party AI connectors used by OpenAI and Anthropic, because those tools pull the same workplace data through Microsoft’s systems. The company has promised a full post-incident review once its technical investigation ends, and it is still watching its systems while the last backed-up emails clear.
US Flight Ground Stop Explained: Why the FAA Halted Flights explains another major system failure from the same week. Read more of our Technology coverage.
Sources: Microsoft service health updates, Reuters, BBC, The Verge, GeekWire.
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