Microsoft said on Saturday morning that its services are fully restored after a worldwide outage that left Outlook, Teams and Copilot out of reach for much of Friday, disrupting businesses, hospitals, courts and government offices in more than 70 countries.
The company said early on Saturday that work to fix the underlying problem was complete and that customers using its main workplace tools should no longer be affected. "We have completed our efforts to address the underlying issue of the incident and restored service to the remaining impacted customers and regions," Microsoft said in a post on X.
More than 430 million people use the products caught up in the failure. The outage, one of the longest Microsoft 365 disruptions in recent years, knocked out email, workplace messaging and the company's artificial intelligence assistant for more than a day, and many organizations were still working through a backlog of delayed messages and calendar items on Saturday.
Trouble first surfaced on Thursday, when users began reporting that they could not reach Microsoft 365 products. Microsoft acknowledged at 17:54 GMT on Thursday that users in the Americas were unable to access Exchange Online mailboxes, and shortly afterwards warned that the disruption could be affecting the wider Microsoft 365 suite.
By 13:32 on Friday, the company reported broader improvements in North America, sustained improvements across much of Europe and encouraging signs of recovery in the Asia Pacific region. Services were beginning to recover by Friday afternoon UK time, nearly 24 hours after the problems first emerged, and Microsoft said it restored services gradually because of the scale of the problem and to help ensure they stayed stable once they were back online.
Microsoft said the failure was a technical issue introduced during a network capacity upgrade, and it was not caused by a cyberattack or by an artificial intelligence agent. "We are deeply sorry for the disruption this incident has caused our customers and partners," the company said. "We know the trust they place in our services and take that responsibility extremely seriously."
The incident, tracked as MO1550821 in the Microsoft 365 admin center, affected connections between Microsoft 365 and AI assistants as well as the core email and collaboration tools. Microsoft said it would publish a full post-incident report once its review is complete.
The outage came in the same week as two other major technology failures: the Federal Aviation Administration's nationwide ground stop on Friday and a Workday outage that locked employees out of payroll and human resources systems. Homeland Security Secretary Markwayne Mullin confirmed there was "no Microsoft link" to the air traffic shutdown, and officials said the incidents were not connected.
Microsoft had already apologized on Friday, when it said the underlying issue had been fixed and it was seeing "broad recovery and stability" across its services. Saturday's announcement closed the incident, with the company saying service had now been restored to all customers and regions hit by the failure.
The disruption stands as one of the worst IT failures in years for a company whose workplace tools serve hundreds of millions of people, and experts said it was a stark reminder of how much businesses and governments rely on a handful of big technology providers. Microsoft said it had paused deployments and moved traffic off affected servers while engineers worked to bring systems back.
