A widespread Microsoft 365 outage disrupted business operations around the world on Thursday, November 12, leaving customers unable to access email, collaboration tools, and other cloud services for much of the day.
The problems began with Outlook and Microsoft Teams in the Americas before spreading globally. What started as a disruption to business communications eventually affected several of Microsoft’s enterprise platforms.
Microsoft later confirmed that a large number of servers had unexpectedly gone offline, putting additional strain on its remaining infrastructure. The company is still investigating what caused the failures.
Why It Matters: The outage affected services that many organizations depend on to keep daily operations running, leaving limited options when multiple systems became unavailable at once. The incident reinforces the importance of planning for disruptions that extend across an entire cloud environment, especially when recovery depends on the provider’s ability to restore service.
- More Than an Email Outage: While Outlook and Teams were among the first services affected, the disruption eventually reached SharePoint Online, Microsoft 365 Copilot, and Microsoft Defender XDR. Some customers also reported trouble accessing Intune administration dashboards and cloud-based Windows computers. The number of affected services meant organizations were dealing with problems across multiple parts of their technology environments, including systems used to manage security and employee access.
- Unexpected Server Failures: Microsoft initially identified elevated infrastructure load as the likely source of the disruption. Further investigation revealed that a large number of servers had unexpectedly become unavailable, placing additional demand on the remaining systems. Engineers also discovered that a process running on affected servers was becoming overwhelmed, reducing available capacity and making it more difficult to restore normal service.
- A Complicated Recovery: Getting services back online required Microsoft to redistribute traffic across its global infrastructure while gradually restoring affected servers. The company paused deployments and investigated whether reversing recent configuration updates could help. Initial recovery efforts did not provide the expected improvements, but by Thursday evening, engineers had successfully returned some servers to operation and reported limited recovery.
- Email Backlogs Remain: By Friday morning, Microsoft reported that email delivery and service availability were improving, although some customers continued to experience intermittent problems. Messages delayed during the outage began reaching inboxes as engineers worked through accumulated queues. To help preserve those emails, Microsoft extended its email timeout window to 48 hours while continuing to restore capacity across its infrastructure.
- Another Major Disruption: The cause of the outage remains under investigation, although Microsoft said it found no evidence of malicious activity. The incident comes just over two months after a separate Microsoft cloud outage in September, when an authentication configuration issue prevented customers from accessing services for several days. Although the incidents have not been linked, the latest outage marks another extended interruption to Microsoft’s cloud services within a matter of months.
Massive Microsoft 365 outage disrupts Outlook, Teams, Copilot worldwide – BleepingComputer
Microsoft reports ‘encouraging recovery progress’ in global outage that has impacted millions – CNN
