· Microsoft says Outlook outage is improving as sustained service gains are reported ↓
Microsoft is working to restore access to its Microsoft 365 workplace software after a widespread outage left customers unable to connect to services including Outlook, Microsoft Teams and Copilot. Users reported problems worldwide, and Downdetector was tracking more than 100,000 reports of user issues with Microsoft services shortly after 1 p.m. New York time, according to Bloomberg News, though the number of reports had since declined for products including Outlook and Copilot.
In a Microsoft 365 admin center advisory tracked as MO1550821, the company confirmed that customers may be unable to connect to multiple services, including Exchange Online, Microsoft Teams, SharePoint Online, Microsoft 365 Copilot and Microsoft Defender XDR. Exchange Online is the system that backs the Outlook email service. The incident began Thursday at 1:26 p.m. ET, although Microsoft had earlier begun investigating reports of Exchange Online mailbox connectivity problems in the Americas. Downdetector also logged complaints across Azure, OneDrive and the Microsoft Store.S1S2
Microsoft first attributed the disruption to elevated infrastructure load across multiple regions, but later determined that the problem was caused by a number of servers unexpectedly becoming unavailable, which strained the remaining infrastructure. Microsoft said it had paused all deployments, redistributed connection traffic across its global infrastructure, moved additional traffic away from affected systems and was restarting affected servers to restore capacity.S1S2
The outage followed a separate Microsoft Teams incident earlier Thursday, tracked as TM1550488, which lasted from 9:45 a.m. to 10:53 a.m. ET and affected users in North and South America. That incident caused delays or failures when sending messages, errors creating or updating conversations and problems retrieving chat messages, which Microsoft attributed to resource contention that elevated resource utilization. Microsoft said the earlier Teams incident had been fully resolved, but it has not indicated whether the two incidents are related, and the wider Microsoft 365 outage had not yet been resolved at the time of reporting.S1
Outage hits Microsoft 365 for more than five hours; Outlook reports fall to about 34,490
- Khaleej Times reported that Microsoft 365, Outlook and Teams stayed disrupted for thousands of users for more than five hours, with connectors used by OpenAI and Anthropic also affected.
- Khaleej Times reported that by 6 p.m. ET Microsoft was still returning affected servers to service and had seen limited recovery as users gradually reconnected.
- According to Downdetector, Outlook problem reports peaked at 138,058 around 1 p.m. ET and had fallen to about 34,490 by evening.
- Microsoft said the disruption came from a number of servers becoming unexpectedly unavailable under elevated load, not from an increase in traffic.
- Deutsche Welle reported that Downdetector received reports from 74 countries and territories within about an hour.
Microsoft says Outlook outage is improving as sustained service gains are reported
- Microsoft said by 10 a.m. Eastern there had been sustained improvements in service, according to Wol.
- Microsoft said it saw no evidence of malicious activity associated with the incident, according to Wol.
- Core functions of Teams and Copilot were back online by early Friday, Microsoft said, according to Wol.
- Microsoft said returned servers could become unresponsive again once traffic reached them, according to Dev.
- Businessinsider reported that the outage was also affecting Claude for Outlook, according to Businessinsider.
