"We have completed our efforts to address the underlying issue of the incident and restored service to the remaining impacted customers and regions," the company said in an update on X.
Users reported that Microsoft 365 services, including Outlook, Teams and AI assistant Copilot, were interrupted. Downdetector, an online tracker, said it received outage reports from users in more than 70 countries and territories.
The outage affected governments, courts, healthcare services, businesses, airlines and banks in many places. Governments including those of Japan, Singapore and Australia reported that the hourslong episode had impacted some of their operations.
Over 430 million people use Microsoft 365 apps, Microsoft said on its website. Problems started appearing around midday Thursday in the U.S.
The Redmond, Washington-based company apologized on Friday for the disruptions and said the outage was "not related to cyber" or artificial intelligence agents.
It said the incident "was introduced by an issue during an earlier network capacity upgrade that surfaced" following a recent network change.
The disruptions offer the latest example of the cascading problems that can erupt when so many communications and technology platforms depend on the same provider. Some lawmakers outside the U.S. have also argued that the outage shows the consequences of overreliance on American tech.
"With no emails coming or going, many office workers feel like they are having a virtual snow day," said Jeremy Singer, a professor at the University of Glasgow's School of Computing Science.
Still, he added, "this problem serves to emphasize the dependence we have built on one company's digital infrastructure, and may lead us to question whether we need more resilience in our IT ecosystem."
The global reach of the outage was swift. After problems first emerged midday Thursday in the U.S., online tracker Downdetector said it received outage reports from 74 countries and territories within an hour.
The total number of people affected was not clear, but Microsoft said in January it had more than 450 million paid commercial subscriptions to its 365 services.
A series of posts by Microsoft 365 on X suggested its engineers struggled to get the problem under control for some time, drawing teasing from other companies and users alike. But the tech giant has said there is "no indication" that the disruptions were caused by malicious activity, specifically noting Friday that the outage was not related to a cyberattack or artificial intelligence agents.
Microsoft said a technical issue arose during an upgrade that followed "a recent network change." The company added that it restored services gradually, which took longer.
As Microsoft addressed issues affecting its Exchange Online mailboxes, it earlier cited a failure that it said caused a number of its servers to be "unexpectedly unavailable" during automated checks.
For Outlook, many users said they couldn't send or receive emails, or had trouble loading their inboxes altogether. Those problems piled up across much of the world into Friday.
In Britain, the outage brought a halt to a trial in Manchester. Judge Maurice Greene sent jurors home because of delays that he said illustrated the danger of the court's reliance on technology.
The British government said it was "working closely" with Microsoft to assess any impact on public services but that "robust contingency plans" were in place to minimize disruption.
British police said they were unable to receive crime reports online and urged people to phone in urgent requests. The outage also affected some law enforcement in the U.S. The sheriff's office in Colorado's Arapahoe County, for example, noted that online bond payments were affected.
Also in Britain, the National Pharmacy Association warned customers of delays in getting medication. The outage affected the National Health Service and threatened to prevent doctors from emailing prescriptions to pharmacies.
"Please bear with your pharmacy teams today, where waits may be longer than normal and there may be delays to some prescriptions," a spokesperson said.
