Microsoft 365 Outage Knocks Out Outlook, Teams for Thousands of Users
A widespread Microsoft outage on Thursday disrupted Outlook, Teams and other 365 services as the company restarted failing servers across several regions.
A widespread Microsoft outage on Thursday cut off access to Outlook email, Teams and a growing list of other Microsoft 365 services for businesses and individual users, as the company worked through the afternoon to restart and repair servers that had unexpectedly stopped responding. Microsoft said a fix was showing promise by late afternoon in the eastern United States, but some services were still listed as affected hours after the problems began.
What happened
The disruption began shortly before 1 p.m. Eastern time, according to CNBC. Downdetector, a website that tracks service outages based on user reports, showed about 130,000 reports of problems with Outlook at one point, CNBC reported, with complaints coming from multiple regions.
A Microsoft spokesperson told CNBC the company was investigating reports of trouble involving “primarily issues with Exchange Online,” the cloud service that powers Outlook email for business and enterprise customers. ABC News reported that users in the Americas had difficulty reaching their mailboxes through several connection methods, and that Microsoft later warned the issue could affect Microsoft 365 connectivity for users in any region.
The problems spread well beyond email. Engadget reported that Microsoft’s own service status page was difficult to load for many of its staff around 2:15 p.m. Eastern time, and that the list of affected products initially included:
- Exchange Online and Outlook
- Microsoft Teams, the company’s chat and video-meeting platform
- SharePoint Online, used by companies to store and share documents
- Microsoft 365 Copilot, the company’s AI assistant for its office software
- Microsoft Defender XDR, a security platform used by corporate IT teams
Around 5 p.m. Eastern time, Engadget said, Microsoft added more services to the impacted list, including Planner, To Do, the device-management tool Intune, Defender for Office 365 and the compliance product Purview. Although Microsoft’s status page referred to business and enterprise customers, Engadget noted that individual consumers were also hit.
What caused it
Microsoft’s explanation shifted as the day went on. The company first attributed the connection errors to “elevated load across multiple regions,” CNBC reported. It later said the strain did not come from a surge in traffic. Instead, according to both CNBC and ABC News, a number of servers had become unexpectedly unavailable, forcing the remaining infrastructure to carry more work than it could handle. Some servers were also failing automated health checks.
ABC News reported that Microsoft had not identified any recent change that coincided with the start of the problems, and that the company suspected a component responsible for processing server health was behind the failed checks. Engadget, citing a separate update, said Microsoft described a core process on the affected servers becoming overwhelmed, which caused the machines to stop responding and reduced overall capacity. Microsoft had not named a single root cause as of Thursday evening.
To contain the damage, Microsoft paused all deployments, moved traffic away from the affected infrastructure and restarted servers, ABC News reported. The company’s status page said it was “restarting and repairing impacted portions of this infrastructure,” according to Engadget.
Signs of recovery, but no all-clear
Around 4 p.m. Eastern time, Microsoft said it had “validated an alternative service health check method” that allowed some affected servers to return to service, CNBC reported. The company said it was rolling that change out more widely and preparing automated recovery systems to continually detect and restart servers that stop responding. It also said it had taken steps to keep additional servers from being affected.
Accounts of the recovery differed somewhat depending on timing. ABC News reported that Microsoft said its mitigation had restored Teams, which had been hit by a separate set of problems in North America, and that its fix for the mailbox issue looked promising but was still being deployed. Engadget, however, reported that at one stage Microsoft acknowledged its actions “have not provided the anticipated relief” and said it was continuing to pursue every available path to restore service. In its latest update Thursday, Engadget said the outage had not been fully resolved and that Microsoft’s status messages suggested a complete fix might not be imminent.
Why it matters
Microsoft 365 is a core workplace tool for a large share of companies, schools and government agencies, so an outage affecting email, messaging, file sharing and security tools at the same time can bring routine work to a halt. The inclusion of security products such as Defender XDR also means some corporate IT teams may have temporarily lost visibility into their own systems during the disruption.
Reports of trouble with other big technology platforms surfaced on Downdetector during the afternoon, including Google, CNBC reported, though it gave no figures and Google did not comment in its report. Amazon Web Services, the cloud computing arm of Amazon, said its services were operating normally and attributed inaccurate news reports to an unrelated disruption elsewhere on the internet, according to CNBC.
Microsoft has not said when it expects all services to be fully restored, and it has not yet identified a single root cause for the server failures. Both ABC News and Engadget labeled their coverage as developing, so details may still change as the company issues further updates.
