A growing number of Microsoft users regained access to email and other services on Friday amid one of the company's biggest-ever server issues that lasted more than 20 hours, causing disruption to millions of its customers.
Engineers scrambled to solve connectivity problems that began shortly before 1 p.m. ET on Thursday.
Email and calendar service Outlook, along with multiple Microsoft 365 services such as Sharepoint and Copilot, were largely down during the morning hours in the U.S. on Friday and throughout the Asian and European business days. Numerous external services that connect with Microsoft products were also hit.
In an update around 10:30 a.m. ET, Microsoft noted "encouraging recovery progress" and said that "service availability and email delivery performance [was] improving across a growing portion of affected infrastructure" as Outlook and other Microsoft 365 tools began to come back online.
In an earlier update Friday morning, Microsoft said that email queues were "approaching normal levels," but that intermittent issues were expected as recovery efforts continue. It had previously given updates by region, with Asia Pacific services among the first to start normalizing.
Engineering teams have been taking affected systems offline for fixes and bringing them back online in stages. They are prioritizing efforts to preserve emails delayed during the recovery process and reduce email queues and backlogs, extending the timeout window, whereby delayed emails continue to attempt delivery, to 48 hours to help protect messages.
Microsoft says it has not detected any malicious activity causing the outage, which it initially blamed on a traffic surge in part of its infrastructure and issues with a component responsible for processing server health.
The company said in its initial updates on Thursday that the connectivity problems related to infrastructure "elevated load across multiple regions," caused by a "number of servers being unexpectedly unavailable; straining the remaining infrastructure." Some servers were failing automated health checks, it said.
Microsoft shares traded largely flat Friday.
Governments and businesses in Asia-Pacific and Europe said they were monitoring the situation, which was causing widespread disruption.
The U.K.'s National Health Service said the outage was affecting some of its services but that patients should attend appointments as normal. Calls "may be subject to long waits" as a result of disruption to the organization, a hospital group serving South West London and the English county of Surrey said on X.
Earnings for Swiss luxury goods giant Richemont were slightly delayed on Friday due to the outage. Electric truck maker Workhorse Group, which was expected to report third-quarter results on Nov. 12, rescheduled the release to Nov. 16, citing business disruptions caused by the global Microsoft outage.
Air India said it had "temporarily rerouted" emails so it could continue to receive customer messages, adding that its flight operations were not affected.
David Ryder | Reuters
Australian Home Affairs and Cyber Security Minister Tony Burke said in a press conference that Microsoft "believe they are dealing in some ways similar to what we saw with respect to CrowdStrike where there is an update that has gone awry," Reuters reported.
A fault with an update issued by cybersecurity company CrowdStrike caused one of the world's biggest IT system outages in 2024, hitting airlines, banks and more.
Microsoft reported in 2025 that Copilot, its collection of AI assistants and tools, had more than 100 million monthly active users.
The incident highlights a business "resilience and dependency issue that has been decades in the making," James Owen, managing partner of Digital Risks at consultancy Control Risks, said by phone.
"We have become, organizationally in the private sector and more broadly, increasingly dependent on a smaller segment of technology and infrastructure as critical to daily life and business activities."
"Organizations are becoming more aware through a geopolitical lens about what technologies they adopt, whether their services are provided by firms in the U.S., or China, or elsewhere, but this shows the importance of proper recovery planning in the case of an IT outage. That could be manual backups, protocols that do not require internet connection, investing in diverse suppliers and crisis management planning rehearsals," he said.
Amazon Web Services and Google users also reported outages on the site on Thursday.
Amazon wrote on X that services were "operating normally" and an "unrelated disruption elsewhere on the internet is prompting some inaccurate news reports." The company referred users to its health dashboard for "accurate data."
At 4 p.m. ET Thursday, Microsoft said it had "validated an alternative service health check method" that brought some affected servers back online.
"We're now applying this change more broadly," Microsoft wrote. "We're also preparing automated recovery systems to continually detect and restart unresponsive servers, to maintain service stability while this change progresses."
