Microsoft is reporting widespread improvements to its services after a global outage took them offline on Thursday, disrupting communications and work at schools, government agencies and offices around the world. The company, headquartered in Redmond, Wash., said on Friday that it was seeing “encouraging recovery progress, with service availability and email delivery performance improving across a growing portion of affected infrastructure.”
“We remain focused on addressing residual impact and ensuring reliable service restoration,” the company added.
Here’s what to know as of Friday afternoon.
What happened?
Outages started disrupting Microsoft tools and apps around noon Eastern time on Thursday and quickly spread to more than 70 countries and territories, affecting millions of users, according to Downdetector, an outage-tracking site.
Some of Microsoft’s most popular products, including the email manager Outlook, the workplace messaging and video calling app Teams and the artificial intelligence assistant Copilot, stopped working.
Was this a cyberattack?
Microsoft said in a statement on Friday that “for now, we can confirm that there is no indication this is the result of malicious or cyber activity.” It added that the problem was “a technical issue not related to cyber or A.I.” agents.
So why were Microsoft’s systems not working?
The company has yet to provide a clear answer, although it has promised to make public a full report that identifies the “root cause” of the outage.
In statements on Thursday and Friday, it provided some details.
Microsoft said on Thursday that “a portion of infrastructure” was experiencing “elevated load across multiple regions, which is likely contributing to the connectivity errors.” That could mean that increased stress on its network was caused by a “number of servers being unexpectedly unavailable, straining the remaining infrastructure,” the company said.
Microsoft said the servers were failing health checks — periodic, automated assessments that ensure they are functioning correctly and efficiently. It said the failed health checks “may originate from a specific component that’s responsible for processing server health.”
On Friday, Microsoft said the problem had been introduced to the system “during an earlier network capacity upgrade that surfaced following a recent network change.” It said it had addressed the underlying issue, allowing its tools and apps to begin to function normally again.
“Given the scale of demand, we restored services gradually, validating stability at each stage,” it said. “While this took longer, it helped ensure a stable restoration.”
Luca Arnaboldi, an assistant professor of cybersecurity at the School of Computer Science at the University of Birmingham in England, said the outage was a reminder that when people use “the cloud,” they are actually relying on servers, which have finite resources.
“In this particular case, as servers became unavailable, capacity on the remaining servers increased, leaving fewer machines to handle the traffic,” he said in a statement. Even after some of the original servers came back online, he added, “the ones currently under strain now fail, creating a constant catch-up.”
Who was affected?
Parents struggled to contact their children’s schools, some government services faltered and many office workers could not access email.
The outage affected parts of the federal government, including the U.S. House of Representatives, according to Samantha Carter, a spokeswoman for the office that oversees House operations.
“We have seen improvements to Outlook’s functionality this morning, but will continue to monitor the situation until all issues are resolved and full functionality is restored to all Microsoft applications,” Ms. Carter said in an email on Friday.
Elsewhere in the world, Britain’s National Health Service said the outage was having a “disruptive impact.” The National Pharmacy Association of Britain said the issues at the N.H.S. were making it difficult for pharmacies to communicate with doctors and some patients, which could cause delays in filling prescriptions. The Metropolitan Police in London said its online contact forms weren’t working.
In Australia, intelligence and police forces said that their operations had been affected. Singapore told taxpayers that email had been disrupted, and the Supreme Court of the Philippines and the European Court of Human Rights said the outage could cause delays in its work.
Reporting was contributed by Isabella Kwai , Karla Adam and Adeel Hassan .
