A widespread outage in Microsoft 365 services left users unable to access email, calendars and related tools for more than 13 hours, beginning late on November 12 and stretching into Friday. The incident hit Outlook hardest while also interfering with Teams scheduling, Microsoft 365 Copilot and other connected applications across multiple regions.

Microsoft traced the problem to an overload in processes that handle encrypted connections and authentication on its servers. A surge in internal traffic between routing systems and backend servers prevented many machines from processing requests. The company also linked the start of the disruption to a recent network configuration change that it later began reversing.

Scope of the Disruption

Users reported trouble sending or receiving messages, delayed email delivery and failures when trying to open mailboxes on web, desktop or mobile platforms. In Teams, chats and online meetings largely continued to function, yet calendar features and meeting invitations that depend on email services failed. Microsoft 365 Copilot often stopped responding or could not access email and calendar data. SharePoint files stored directly in the service remained accessible for opening, editing and saving, though shared mailboxes and calendars tied to Exchange Online experienced problems.

The outage also disrupted connectors used by external AI tools, limiting their ability to link with Outlook and Teams. Security tools such as Defender, Intune and Purview faced additional impacts. Complaints peaked in regions including India, where reports reached roughly 138,000 around 1:30 a.m. local time before declining later in the morning.

Recovery Efforts and Timeline

Microsoft engineers applied configuration patches, restarted affected servers and added virtual machines to increase capacity. Early repair attempts triggered further internal traffic spikes, prompting a more measured approach that verified each fix before wider deployment. By early afternoon India Standard Time, the company reported that a patch to an authentication and routing component had begun stabilizing parts of the infrastructure and was being expanded as regions returned online.

The company provided regular status updates throughout the incident, including scheduled reports around 11:30 a.m., 12:30 p.m. and 1 p.m. IST. It repeatedly stated that it found no evidence of malicious activity and committed to publishing a detailed post-incident report after full resolution. No firm timeline for complete restoration was issued while work continued.

Business Impact

Nearly four million businesses worldwide rely on Microsoft’s office software. Professional services firms faced estimated costs exceeding $100,000 for every hour the services remained unavailable. Total economic losses were expected to reach into the billions of dollars, with smaller companies particularly exposed because many depend heavily on email and lack alternative systems.

The outage began in some reports around noon Eastern Time on November 12 and expanded globally. In Australia, disruption was noted from approximately 3:15 a.m. Sydney time on Friday. Microsoft continued monitoring server performance across regions and confirmed that patches were taking effect after reboots while capacity was increased to reduce load on overwhelmed systems.