Microsoft apologizes for massive outage that took down Outlook and other 365 services
Microsoft apologized on Friday for a global outage that shut down Outlook and other Microsoft 365 services for nearly 24 hours, blaming an issue during a network capacity upgrade.
Sorry, and still recovering
Microsoft issued an apology Friday for a wide-ranging outage that shut down Outlook and other Microsoft 365 products, as the company worked to restore service nearly 24 hours after connectivity problems began. "We are deeply sorry for the disruption this incident has caused our customers and partners," a Microsoft spokesperson said Friday. "We are seeing broad recovery and stability across our services."
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. In an update around 10:30 a.m. ET, Microsoft noted "encouraging recovery progress" and said service availability and email delivery performance was improving. Reuters reported the outage lasted more than 12 hours on November 12, with disruption extending into the following day.
What went wrong
In a statement, Microsoft said the connectivity disruption stemmed from "an issue during an earlier network capacity upgrade." The company said the underlying cause of the outage had been addressed and that it was still working to restore services to some customers. In its initial updates on Thursday, the company said 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.
At 4 p.m. ET Thursday, Microsoft said it had "validated an alternative service health check method" that brought some affected servers back online. Engineering teams have been taking affected systems offline for fixes and bringing them back online gradually in stages, extending the timeout window for delayed emails to 48 hours to help protect messages. Microsoft says it has not detected any malicious activity, and the company said it would issue a full report once its assessment was complete. Australian Home Affairs Minister Tony Burke said Microsoft believes it is dealing with something similar to the CrowdStrike update fault in 2024, Reuters reported.
- Outage beganshortly before 1 p.m. ET, Thursday
- Outage lengthmore than 12 hours
- Time to broad recoverynearly 24 hours
- Delayed-email timeout window48 hours
- Copilot monthly active usersmore than 100 million
- Microsoft shares, Fridayup $1.49, or 0.28%
The fallout, from hospitals to earnings
Governments and businesses across the U.S., Asia-Pacific and Europe said they were monitoring the situation. The U.K.'s National Health Service said the outage was affecting some of its services but that patients should attend appointments as normal, though calls "may be subject to long waits." 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 November 12, rescheduled the release to November 16, citing business disruptions caused by the global Microsoft outage.
U.S. Rep. Josh Gottheimer told CNBC he asked for a briefing on the 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. Microsoft reported in 2025 that Copilot, its collection of AI assistants and tools, had more than 100 million monthly active users. Amazon Web Services and Google users also reported outages on Thursday, though Amazon said its services were "operating normally." Microsoft shares traded largely flat Friday, up $1.49, or 0.28%, in the article's market data.
