Overview of the Outage

Microsoft's 365 business and enterprise services suffered a significant outage on Thursday, impacting users' ability to access their accounts. The outage began around 10:40 AM ET and continued until Microsoft began redistributing connection traffic and restarting affected servers.

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Detailed Timeline of the Outage

  • 10:40 AM ET: Microsoft posted on its 365 status page that it was investigating reports of users experiencing issues when accessing or using Microsoft Teams functionality in North America.
  • Before 1 PM ET: Microsoft acknowledged issues accessing Exchange Online mailboxes through multiple connection methods in the Americas.
  • 1:15 PM ET: Downdetector began receiving reports of users experiencing issues with Outlook and other Microsoft 365 products.
  • Before 3 PM ET: Microsoft stated that a problem was causing servers to fail automated health checks and become unavailable, and it was attempting to reboot its systems to hopefully bring them back online.

Affected Services

The outage affected multiple services, including:

  • Exchange Online: The primary email service for Microsoft 365.
  • Microsoft Teams: A collaboration and communication tool.
  • SharePoint Online: A cloud-based document management and collaboration platform.
  • Microsoft Copilot 365: An AI-powered productivity assistant.
  • Microsoft Defender XDR: An endpoint detection and response tool.

Microsoft's Response

Microsoft acknowledged the issue and stated that it was aware of the problems with Exchange Online. The company paused all deployments, moved additional traffic off the affected infrastructure, and restarted affected servers to return services to service. The company appreciated its customers' patience while it worked to restore services as soon as possible.

Potential Causes

While Microsoft did not specify the cause of the outage, it is currently unclear whether a cyberattack or configuration errors were the root cause. Previous major outages have been attributed to issues with the Domain Name System (DNS) resolution or corrupted updates from security firms.

Industry Context

Major Microsoft outages are relatively rare, but they are not unprecedented.

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