Quick summary: On Thursday, November 12, 2026, Microsoft 365 suffered one of its biggest outages of the year. Outlook, Teams, SharePoint, Copilot and several security tools stopped working for users in dozens of countries. Microsoft says it was not a cyberattack. Here is what happened, why it happened, and what you can do to protect your work the next time Outlook goes down.
What happened?
The trouble started in the morning (US Eastern time) with a short Teams incident in the Americas, where chat messages were delayed or failed to send. A little later, at around 11:17 AM ET, Microsoft opened an incident for Exchange Online, the service that powers Outlook mailboxes. By early afternoon the problem had spread and Microsoft confirmed that users in any region could be affected.
For most people the symptoms were simple and frustrating:
- Outlook would not load, or showed "Cannot connect" errors on web, desktop and mobile.
- Emails got stuck in the Outbox or arrived hours late.
- Teams failed to connect, and meetings dropped.
- Copilot Chat would not load or could not read email, calendar or files.
- Safe Links in Defender for Office 365 could not check links, so some links in Outlook and Teams would not open.
According to Euronews, the disruption reached Microsoft users in 74 countries and territories and lasted through most of the US workday. Outage-tracking site Downdetector showed reports climbing for Outlook, Teams, OneDrive and Microsoft 365 at the same time, which is why "Microsoft outage" and "is Outlook still down" became the top technology searches on Google Trends this week.
What caused the Microsoft 365 outage?
Microsoft has not published a full root-cause report yet, but its status updates give a clear picture. A large number of servers failed Microsoft's automatic health checks and were pulled out of service. The remaining servers then had to carry far more traffic than normal, a situation Microsoft described as "elevated load." A process that sets up secure connections became overwhelmed, so the servers stopped answering requests.
In the evening, Microsoft said that restarting the affected servers was helping, but it kept monitoring because some servers could stop responding again under heavy load. The company tracked the problem as incident EX1550543 (Exchange Online) and MO1550821 (the wider Microsoft 365 suite) in the admin center.
Was it a cyberattack?
No. Microsoft said it was "not aware of any malicious activity," and nothing in its updates points to hackers or a denial-of-service attack. This was an infrastructure failure inside Microsoft's own cloud. Be careful, though: big outages are a favourite moment for scammers. Fake "Microsoft support" emails, calls and pop-ups asking you to "re-verify your account" often appear right after a major outage. Microsoft will never ask for your password through email or a phone call.
Is Outlook working now?
Late on November 12, Microsoft said restarting the affected servers was improving the situation, but some users were still reporting problems on November 13 and Microsoft had not yet confirmed full recovery. If Outlook is still acting strangely for you, try these steps in order:
- Check the official status first. Visit the Microsoft 365 Service Status page or the @MSFT365Status account on X. If the problem is on Microsoft's side, there is nothing to fix on your PC.
- Restart Outlook and Teams completely. Close them from the system tray (Windows) or force-quit them (Mac), then open them again.
- Try another app. If the desktop app fails, try Outlook on the web (outlook.office.com) or the mobile app, and the other way round.
- Send stuck emails again. Open the Outbox and press Send/Receive. If a message is still stuck, copy its text into a new email.
- Clear the cache if errors continue. Signing out and back in, or clearing the browser cache for Outlook on the web, fixes most leftover problems after an outage.
How to protect your work from the next outage
Cloud outages are rare, but this was not the first one in 2026. Microsoft also had Exchange Online problems in April, June and August this year. A few simple habits can save you a lot of stress:
- Turn on Cached Exchange Mode in desktop Outlook so you can still read old emails and your calendar while offline.
- Keep a backup contact channel. Agree with your team on WhatsApp, Slack, Google Chat or a simple phone call list for emergencies.
- Sync important files locally. Use OneDrive's "Always keep on this device" option for documents you need every day.
- Write down important meeting links and phone dial-in numbers before the day starts.
- Admins: subscribe to Service Health alerts in the Microsoft 365 admin center and prepare a short message template for staff.
Why this outage matters
Millions of businesses, schools, hospitals and government offices run on Microsoft 365. When it stops, emails, approvals and meetings stop with it. This outage is another reminder that "the cloud" is still someone else's computer, and even the biggest companies have bad days. The smart move is not to panic, but to have a simple Plan B ready.
FAQ
When did the Microsoft outage start?
Microsoft lists 11:17 AM ET on November 12, 2026 as the start of the Exchange Online incident, after a smaller Teams problem earlier that morning.
Which services were affected?
Outlook (web, desktop and mobile), Exchange Online, Teams, SharePoint, OneDrive, Copilot and Defender for Office 365.
Did I lose my emails?
No. Emails were delayed, not deleted. Most delayed messages were delivered once the servers recovered.
Sources
- SecurityWeek: Microsoft 365 outage disrupts Outlook, Exchange Online and Teams
- Euronews: Microsoft racing to fix global outage affecting Outlook, Teams and Copilot
- TechRadar: Microsoft outage live updates
- Tom's Guide: Outlook, Microsoft 365 and Teams outage live updates
- eBuilder Security: incident IDs EX1550543 and MO1550821
- The National CIO Review: earlier 2026 Exchange Online outages
Update (November 13, 2026): This is a developing story. Microsoft has not yet published a full root-cause report. We will update this article when it does.