Healthcare services were disrupted, corporate earnings reports delayed and schools struggled to communicate on Friday as a widespread outage affecting several Microsoft products, including Outlook, rippled across the globe, with no indication of when full service would be restored.
Microsoft reported "encouraging recovery progress" in Europe and service improving in North America, but a top UK trade union said the disruptions were having a "serious impact" on the country's health care service.
National Health Service staff receiving emergency calls were "unable to refer patient details in the normal way which is creating a massive backlog and has the potential for chaos," said Rachel Harrison, public services head at the GMB union.
In London's financial district, several people interviewed by AFP said the outage exposed their reliance on Copilot, Microsoft's AI assistant.
"I think one of the biggest things is Copilot not working, and you can sort of see the dependency now on Copilot," said Yashmit Sharma, 26, an auditor. "I think this was the main bummer. And Outlook as well, of course."
Sheera, 40, a risk manager at a mid-sized bank, said businesses needed to be better prepared for unexpected technology failures.
"I think we need to be a little bit more careful," said Sheera, declining to give her last name. "Anything can happen: you wake up and Outlook is not working and it's the main communication we use for our global team.
Microsoft attributed the disruption to "elevated load" on its infrastructure, while reports of problems on Downdetector, which tracks digital outages, had begun to decline by 0900 GMT, suggesting some improvement.
The tech giant also noted that it was "not aware of any malicious activity that is causing this incident."
But the company has reported having difficulties in fully restoring service, despite the fixes it has put in place.
The disruption went global within an hour, knocking out Microsoft products in 74 countries and territories, Downdetector reported.
A map posted by Downdetector on X showed the outage affected users across the Americas and parts of Europe, Asia and Africa.
Airlines in India warned that customer queries may not be getting through, and New Zealand said the outage forced a halt in the processing of visa applications. Japan cautioned the impact would be broad.
Japan's economy, trade and industry minister Ryosei Akazawa said there was no doubt that the outage would cause a "significant impact."
"Since this software is used by a vast number of people, we will closely monitor the situation and take every possible measure to address it," Akazawa told Japanese newspaper Asahi Shimbun.
Indian airlines IndiGo and Akasa Air both said on X that their email support services have been affected and that they may not be able to receive customers' emails.
The Australian Computer Society (ACS) called for a national review of sovereign IT risk, with CEO Prins Ralston saying that small businesses may not have a workaround when Outlook fails.
"We need to know the systems that keep this country running won't simply fall over without notice," Ralston said, according to ACS publication Information Age.
Immigration New Zealand said it has paused the processing of all visa applications until further notice because of the global Microsoft outage.
Microsoft initially said it was investigating outage reports "in the Americas," but later confirmed that the issue apparently affected "Microsoft 365 service connectivity for users in any region."
Microsoft 365 is the company's cloud-based subscription service that includes popular applications such as Outlook and Teams.
"We've determined a portion of infrastructure is experiencing elevated load across multiple regions, which is likely contributing to the connectivity errors," the company wrote on X.
"We're aggressively pursuing all pathways to reduce impact," it added.
Thousands of users also reported issues with Teams and Copilot, according to Downdetector.