Microsoft 365 outage hits 74 countries; Outlook, Teams and Copilot knocked offline

A widespread Microsoft 365 outage disrupted core workplace applications — including Outlook, Microsoft Teams, SharePoint, and Copilot — for several hours spreading across 74 countries and territories after automated server health checks failed and triggered a cascading drop in cloud capacity.

According to Microsoft, the Exchange Online incident began at 16:17 UTC. Within roughly an hour, user complaints on outage-tracking platform DownDetector surged worldwide, peaking at 19,650 reports per minute across five combined Microsoft services by 18:25 UTC — compared to fewer than 15 reports a minute on November 12.

At the time of filing this report the services were still down.

"Microsoft's outage reports on November 12 reached 74 countries and territories in about an hour on Downdetector. Microsoft says its Exchange Online incident began at 16:17 UTC. Reports to Downdetector about Outlook began climbing at about 17:25 UTC, 12:25 in New York. By 18:25, reports about five Microsoft services combined reached 19,650 a minute, against less than 15 a minute on an average Thursday," DownDetector said.

"Outlook reports alone peaked at more than 2,000 times their normal level," DownDetector added. "Reports did not stay in the Americas. They jumped tenfold in the UK at 17:43, in India at 23:21 local time and in New Zealand at 06:55 local time. Between 17:00 and 18:55 UTC, nearly 3 in 10 reports came from outside the US. We count a country here once its reports reach ten times normal and at least 20 in five minutes."

DownDetector noted that complaints for Microsoft 365, Copilot, Teams, and OneDrive each jumped more than a hundredfold, while Azure rose roughly a hundredfold. Consumer-facing and developer platforms owned by Microsoft — including Xbox, GitHub, and LinkedIn — saw comparatively minor spikes. Even Microsoft’s public service status dashboard briefly went offline under the strain, and third-party AI providers, including OpenAI and Anthropic, reported connector failures affecting mail and calendar integrations.

"Microsoft said a portion of its infrastructure was experiencing elevated load across multiple regions. At 19:38 UTC, reports were still running at more than 11,000 a minute," DownDetector said.

According to Microsoft, the disruption stemmed from internal infrastructure failures rather than a cyberattack. A large pool of servers unexpectedly failed automated health diagnostics and dropped offline. As user traffic automatically shifted onto the remaining active servers, a core process became overwhelmed by elevated processor usage, causing healthy servers to turn unresponsive in a domino effect.

“We're testing a configuration change to address a problem that's causing servers to fail automated health checks and become unavailable,” Microsoft said in an update on X, noting that it had initiated restarts across affected machines.

To stabilise the network, engineers froze all routine software deployments and configuration updates, rerouted user traffic onto alternative infrastructure pathways, and deployed an alternative health-check method so restarted servers could safely rejoin the network.

By November 12 evening, complaint volumes on DownDetector had dropped from their afternoon highs to roughly 32,000 reports. In a subsequent update on X around 6:57 p.m. ET, Microsoft confirmed that recovery was underway, though it cautioned that full restoration would remain gradual.

"We're returning a portion of affected servers to the service, and they remain stable so far. We're also shifting traffic to alternate routes wherever possible and observing limited recovery. In parallel, we've streamlined the process of returning the remaining affected servers to service. As capacity is restored, users may experience a gradual recovery as their clients reconnect. More info under EX1550543 and MO1550821 in the Microsoft 365 admin center, as well as http://status.cloud.microsoft if the admin center is not available to you," Microsoft said in a post on X.

The incident marks the third major Microsoft 365 disruption this year, following multi-hour outages in January and a code-update failure in August that took several days to fully resolve.