A major global outage affecting Microsoft 365 has disrupted email, calendars, files and AI services for tens of thousands of users across at least 74 countries. Microsoft says the incident is not a cyber-security event, but its initial repairs have not restored normal service as quickly as expected.
Microsoft outage: What we know about the global Microsoft 365 disruption
Reports of problems with Outlook peaked at nearly 140,000 globally at about 18:00 GMT on Thursday, according to Downdetector – more than 2,000 times the normal reporting level. The monitoring site first detected disruption shortly after 16:15 GMT, and issues had persisted for at least eight hours.
Which Microsoft services are down?
Microsoft 365 services, including Outlook, Teams, Exchange Online and Copilot, have experienced “connectivity problems.” Many users have been unable to send or receive email, access files, or view calendar information; some Teams users, however, have still been able to message and join online meetings normally.
Which countries have been affected by the Microsoft outage?
Microsoft says more than 430 million people use Microsoft 365 apps, while between three and four million organisations are estimated to use the platform. The outage has therefore had knock-on effects well beyond individual Office users.
OpenAI said it was investigating an issue affecting its connections to Microsoft services, which caused some tools to work incorrectly.
Anthropic also reported problems with its connections to Microsoft 365 services.
Government bodies, including Singapore’s government and Australia’s spy agency, said they had been affected.
UK GP practices warned patients of potential disruption and advised urgent enquiries by phone rather than email or web forms.
What Microsoft says went wrong
Microsoft has ruled out a cyber-attack and attributed the disruption to “elevated load” on its infrastructure.
Rather than a simple traffic surge, a large number of servers became unexpectedly unavailable, pushing additional work onto the remaining systems and overwhelming a critical component.
The company initially said its fixes were “not taking as expected.” In its latest update, Microsoft said it was seeing “positive results” from restarting affected systems, while continuing to monitor capacity and service availability across regions.
Microsoft’s cloud and productivity services are deeply embedded in workplaces, public services and other technology platforms.
When Outlook, Exchange Online and Copilot fail, the effects can extend to appointment communications, account verification, purchases, file access and internal business operations.
Australian cybersecurity expert Troy Hunt told the BBC that the outage underlines how critical email remains to the internet’s functioning. Paul Spain of Gorilla Technology said companies with email and services offline had effectively “lost a business day.”
How long will the Microsoft outage last?
Microsoft is attempting to restore capacity without overloading systems again, and has warned that services which return could become unresponsive if traffic rises.
The company is also investigating the underlying cause and seeking alternative ways to bring more users back online.
