Hundreds of thousands of people were unable to access their emails, Teams chats or meetings on Thursday night and Friday morning after a Microsoft 365 outage brought down services across the globe.
The incident affected businesses, government agencies, and even Microsoft employees who were unable to email during the more than nine hours of downtime.
What happened and why – and what does it say about online services in 2026?
At around 6pm UTC on Thursday, outage website Down Detector showed a spike in users reporting issues with Microsoft 365 – the suite of cloud software that includes Teams, Word Excel, PowerPoint and Outlook. There were nearly 130,000 reports at the time.
The outage had lasted for more than nine hours at the time of reporting, with Microsoft working to bring services back online.
So far, the problem appears to be a configuration update which has resulted in some servers becoming overloaded and taken offline, Microsoft indicated.
When the company attempted to apply a fix, servers that had come back online again became unresponsive when traffic began returning to them.
As some servers went down, traffic was funnelled on to the remaining servers, causing traffic issues for those remaining online.
To understand what was bringing down the servers, the company began limiting the traffic that could reach affected servers in specific locations, and, on some servers, rolled back to an earlier software configuration to see if it fixed the problem.
As of 2am Friday UTC, Microsoft had narrowed down most of the issues to Microsoft Exchange – the email service behind Outlook. Teams meetings and chats had returned to service.
An outage that runs for more than nine hours for a service as critical as Microsoft 365 is unusual. The company has not said why it has lasted so long, but a clue might be in its updates: as servers returned to being unresponsive after being fixed, engineers had to work through alternative solutions, taking longer than expected to get servers back up and running.
Many people who rely on Microsoft 365 were reporting being unable to access their inboxes on Friday morning in Australia – where the outage has so far had the most impact.
Councils, state and federal government agencies, courts and schools were among those telling the public that they weren’t contactable by email on Friday morning.
Businesses and health care services that rely on Microsoft 365 for communications were also reporting issues but said their own services remained operational.
Given the recent OpenAI agent attack on Medicare, and the spate of cyber-attacks in Europe bringing down internet-connected fridges, some quickly guessed the global outage might be a new attack on critical infrastructure. Microsoft quickly hosed down the idea, saying there was no indication it was a cyber-attack.
As the name Microsoft 365 implies, the world has quickly become accustomed to online services being available 24/7. Given software is no longer solely downloaded to individual PCs but is also stored on a server owned by a company, outages like this will happen. Most of the time they’re brief, but sometimes they’re not.
Outages in recent years from telecommunications providers , from the PHP incident to the Crowdstrike incident , show just how varied the sources and causes of a massive outage can be.
There are so many different pieces of the puzzle keeping services online – but the effects of one of those services going down is much greater than it ever has been.
RMIT associate professor Mark Gregory said on Friday it was important for organisations to thoroughly test updates before rolling them out to the live network. That is in addition to the extra security testing companies must carry out to ensure their services are protected from threat actors armed with AI tools that can find vulnerabilities quicker than ever before.
Gregory has said companies that rely on services such as Microsoft 365 should have back-up options such as Google’s Gmail in the event of an outage.
Others have suggested the free and open-source Office alternative, LibreOffice.
