Microsoft 365 services fully recovered after multi-day outage

Microsoft has confirmed that services across the previously affected environments have fully recovered and that the backlog of email messages has been processed, bringing an end to a widespread Microsoft 365 outage that began on Thursday, November 12, 2026. The company stated that the issue is remediated. The incident, tracked under EX1550543 and MO1550821, started at 10:05 AM UTC on November 12 and ended at 4:10 PM UTC on Friday, November 13, 2026. This marks the final update for the event. On X, the Microsoft 365 Status account reported that efforts to address the underlying issue had been completed and that service had been restored to the remaining impacted customers and regions.

During the outage, users may have been unable to access or perform several actions in Microsoft 365 services. Features that interact with Exchange Online and email services were primarily affected, while elements that did not depend on them remained functional. Many users were unable to access their Exchange Online mailboxes through Outlook on the web, the Outlook desktop client via MAPI, Exchange ActiveSync, or REST-based connections, and email delivery was delayed. In Microsoft Teams, most core functionality including joining calls, meetings, group chats and channel messages continued to work, but scenarios that depended on Exchange Online such as calendar scheduling, invites, viewing and meeting edits failed for many users, as did the creation of Live or Virtual events, certain Copilot responses that rely on Outlook, calendar or Microsoft 365 files, and the ability to create or delete private or shared channels. Microsoft 365 Copilot users were often unable to load Copilot Chat or receive responses in web and desktop apps, and Copilot experiences could not access work data such as email, calendar and files. Other impacted areas included parts of the Microsoft 365 admin center, Microsoft Graph API requests that access Exchange Online data, Microsoft Defender for Office 365 features such as Safe Links and quarantine operations, Microsoft Defender XDR portal pages, Microsoft Purview services including labeling and data loss prevention, certain Intune device scenarios, Planner, To Do, Power BI and Microsoft Fabric exports involving sensitivity labels, Universal Print, and some Windows 365 Cloud PCs configured with Microsoft Purview Customer Key.

The elevated load and connectivity failures stemmed from Exchange Online traffic imbalances created when a large number of servers unexpectedly became unavailable after failing automated health checks. With fewer healthy backend servers able to accept and process requests, the remaining infrastructure was forced to handle a disproportionate share of the traffic. Microsoft stated that the elevated load was not driven by an increase in overall user traffic volume, but by the sudden loss of server capacity, which strained the systems still in service. Subsequent mitigation efforts, including traffic rebalancing and attempts to return servers to service, produced further imbalances: routing services generated surges in outbound calls when they could not properly direct requests to backend machines, and restored servers sometimes became unresponsive again once they began receiving traffic. These sustained traffic management imbalances complicated recovery as the company worked to identify the underlying cause of the original server failures, scale capacity, optimize routing and carefully repair affected infrastructure.

Microsoft has said it is not aware of any malicious activity that caused the incident. Administrators can find further details under MO1550821 in the Microsoft 365 admin center. With services restored and the email backlog cleared, normal operations have resumed across the previously affected environments.