Microsoft 365 Outage Knocks Out Outlook, Teams and Copilot for Millions Worldwide
Microsoft 365 Outage Knocks Out Outlook, Teams and Copilot for Millions Worldwide
Millions of people could not reach their email, chat or files on Thursday, November 12, 2026, after a widespread Microsoft 365 outage knocked out Outlook, Teams and Copilot across the United States and beyond. Microsoft said a large number of its own servers failed automated health checks and became unavailable, and by Thursday evening the company still had not declared the incident over or given a time for full recovery.
The disruption began late Thursday morning and spread through the afternoon, hitting businesses, schools and home users in the middle of the workday. Outlook was the most visible casualty, but the outage reached deep into Microsoft’s cloud suite, including Exchange Online, SharePoint, OneDrive and its Copilot AI assistant.
What went down and when
Microsoft opened its Exchange Online incident, tracked as EX1550543, at 11:17 a.m. ET, after users began reporting that they could not connect to their mailboxes. The problem widened at 1:26 p.m. ET into a broader Microsoft 365 service degradation, tracked as MO1550821, as more services began failing.
Reports on the outage tracker Downdetector climbed fast. Nearly 130,000 users reported problems accessing Outlook just after 1 p.m. ET, and more than 38,000 reported problems with Microsoft 365 itself. New reports have since fallen from that peak, but many users said late into the day that they still could not send or receive email or load their inboxes at all.
A separate Microsoft Teams incident in North America, tracked as TM1550488, struck the same morning. Microsoft declared that one fully resolved at 12:08 p.m. ET, even as the wider Exchange and Microsoft 365 problems kept growing.
What Microsoft says caused it
Microsoft said a portion of its infrastructure was “experiencing elevated load,” which it said was “likely contributing to the connectivity errors.” The company determined that a number of servers were “unexpectedly unavailable” because they failed during automated health checks, and it said the failure may be related to a recent change to a component involved in processing those checks.
Microsoft has not attributed the outage to a cyberattack, and nothing it has published points to one. The company said it was testing a fix and rolling out an alternative method for the health checks to bring affected servers back online, while restarting servers and pausing deployment and configuration changes as it reviews telemetry.
“We’re aggressively pursuing all pathways to reduce impact,” the Microsoft 365 Status account wrote on X.
Which services were affected
The outage reached well beyond email. Under incident MO1550821, Microsoft listed Exchange Online, Microsoft Teams, SharePoint Online, Microsoft 365 Copilot, Microsoft Defender XDR, Microsoft Planner, Microsoft To Do, Microsoft Intune, several Microsoft Purview services, part of Power BI, Universal Print and Windows 365 Cloud PCs that use Customer Key. Users also reported problems with OneDrive, Azure and the Microsoft Store.
Microsoft clarified that only features that work with Exchange Online and email were affected, and parts of these services that do not depend on Exchange Online kept working.
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Why this matters
Microsoft 365 is the daily workspace for hundreds of millions of people, from small businesses to some of the world’s largest companies. When Outlook and Teams stop working at the same time, meetings stall, customer messages pile up and workers lose access to the documents and calendars their jobs depend on.
The outage also landed in a week of heavy tech news. Samsung is in talks to buy data center cooling firm Modine, and Anthropic withdrew IPO pricing details after a nearly $70 billion plan circulated, a reminder of how much of the modern economy now runs on a small number of cloud platforms. When one of those platforms stumbles, the effects show up almost everywhere at once.
Latest developments
As of 7:08 p.m. ET on Thursday, Microsoft still listed Microsoft 365 as a service degradation. The company warned that servers it had returned to service could stop responding again once traffic reached them, and it gave no estimated time for full recovery. Administrators can follow the incident in the Microsoft 365 admin center under EX1550543 and MO1550821.
The search interest alone showed how widely the outage was felt. “Microsoft outage” became the top trending search in the United States on Thursday, with more than 2 million searches, as people looked for answers about whether their email was down and when it would come back.
Frequently asked questions
Is Outlook down because of a cyberattack?
No evidence points to one. Microsoft said the outage came from a large number of its own servers becoming unexpectedly unavailable after failing automated health checks, not from a surge in traffic or an attack.
Which Microsoft services were affected by the outage?
Outlook and Exchange Online were hit hardest, along with Microsoft Teams, SharePoint Online, OneDrive, Microsoft 365 Copilot, Microsoft Defender XDR and several admin and security services. Microsoft said only features that depend on Exchange Online and email were affected.
When will Microsoft 365 be fully restored?
Microsoft has not given an estimated time for full recovery. As of Thursday evening, the company said it was testing a fix, restarting servers and bringing them back online, but warned that restored servers could fail again under traffic.
What to watch next
The next test is whether Microsoft’s fix holds once Friday morning traffic hits the restored servers. Watch the Microsoft 365 Status account and the company’s service status page for a declaration that the incident is resolved, and for the post-incident report that should explain what changed in the health-check component and what Microsoft will do to keep it from happening again.
Sources: Associated Press via WHRO/NPR; BleepingComputer; McAfee; On-Site Technology; Parade.
