The Microsoft 365 platform experienced a large-scale technical outage on Thursday, disrupting access to cloud business services across multiple regions. This disruption affected vital services such as Exchange Online (email), Teams, and SharePoint Online, in addition to Microsoft 365 Copilot and Defender XDR tools.
Microsoft explained that the issue began in the Americas region, where users faced difficulties connecting to mailboxes before the scope of the impact widened to include other services. Some Google Workspace users also reported difficulties accessing their hosted email via Outlook desktop and mobile applications.
Technical Causes Behind the Outage
According to preliminary investigations, the company traced the increased pressure on its infrastructure to the failure of a large number of servers, leaving the remaining systems to bear the full traffic load. Technical reports pointed to the following points:
- Health Check Failures: Affected servers failed to pass automated health checks.
- Secure Connection Pressure: The process responsible for establishing secure connections experienced immense pressure, causing servers to stop processing requests.
- Processor Consumption: The company detected an abnormal rise in processor usage on the affected servers.
Microsoft began rolling back a recent network configuration change that coincided with the start of the disruption as a measure to address the issue and monitor system stability.
What Does This Mean Technically?
This outage reveals the deep interconnectedness of the cloud services environment, where any flaw in a core component like Exchange Online leads to a cascading effect that extends to artificial intelligence tools like Copilot and collaborative platforms like Teams. Although Microsoft has not found evidence of a cyberattack so far, the timing raises questions given that the outage coincided with the release of Patch Tuesday updates that addressed 1,094 security vulnerabilities, including an Outlook vulnerability (CVE-2026-124194), though they have not been officially linked yet.