What We Know About the Global Microsoft 365 Outage

A global outage of Microsoft 365 disrupted email, calendars and artificial intelligence tools starting Thursday, with effects reported from Los Angeles, California, to Tokyo, Japan, before Microsoft said Friday afternoon it had seen "encouraging recovery progress" in Europe and improvement in North America, according to BBC News.

What services were affected?

Microsoft 365 applications including Outlook, Teams and the Copilot artificial intelligence tool experienced what Microsoft described as "connectivity problems," the BBC reported. Users described varying degrees of access: many could not send or receive email, view calendar details or open certain files, while others were still able to use Teams for messaging and online meetings without issue.

How many users were hit?

Microsoft says more than 430 million people use Microsoft 365 apps, per the company's website. The monitoring site Downdetector logged roughly 140,000 reports of Outlook problems from 74 countries on Thursday evening, though the BBC noted that figure almost certainly understates the real toll because Downdetector depends on users self-reporting.

The disruption spread beyond Microsoft's own products. OpenAI said it was investigating an issue affecting its connections to Microsoft's services that left some ChatGPT tools not working as expected, and Anthropic also reported problems tied to the outage, according to the BBC.

Which institutions reported disruptions?

The BBC's reporting lists a wide range of affected organizations. In the United States, city governments and courts — including in Los Angeles and Texas — warned that communications might be delayed. Australian spy agencies reported disruption. Canada's public broadcaster CBC said a healthcare network running several hospitals in Toronto had email problems, though patient care was not affected. Japan's government said its shared IT platform was disrupted.

In the United Kingdom, GP surgeries, pharmacies, police forces and schools were hit. Some GP surgeries asked patients to avoid submitting messages through their websites while the problem persisted, and several large police forces told the public to call rather than file reports online.

What caused the outage, according to Microsoft?

Microsoft ruled out a cyberattack and attributed the disruption to "elevated load" on its infrastructure, the BBC reported. The company said a large number of servers became "unexpectedly unavailable," pushing additional traffic onto the remaining servers and straining them further.

Microsoft said it is "focused on addressing the remaining areas of disruption" and warned that "some users may still experience intermittent issues as recovery actions continue."

What happens next?

• Recovery by region: Microsoft reported improvement in Europe and North America as of Friday afternoon but has not said when full service will return.
• Scale of impact: The true number of affected users remains unconfirmed; Downdetector's 140,000 reports likely understate the total given 430 million Microsoft 365 users worldwide.
• Knock-on effects: Watch for further statements from OpenAI and Anthropic on whether their tools, which rely on Microsoft's infrastructure, have fully stabilized.
• Public services: UK police forces, GP surgeries and pharmacies may continue directing the public to phone lines until online systems are confirmed stable.

This is a developing story. HTT News will update as Microsoft provides further details on the cause and timeline of full recovery.