The key facts
- More than 130,000 complaints about Outlook in the US according to Downdetector; Teams, SharePoint, Copilot, OneDrive and Defender XDR were also affected
- Microsoft cited 'a large number of servers unexpectedly becoming unavailable' as the cause, rather than increased user load
- This is the second major Microsoft 365 outage in a few months: the previous one lasted several days in September
Massive outage of Microsoft services
On November 12, 2026, Microsoft reported a large-scale outage that left business and individual users unable to access their Outlook mailboxes. According to TechCrunch, the problem was initially detected in the United States and countries across the Americas, and was later extended to 'any region'. According to Downdetector data cited by euronews, by 1:30 PM Eastern Time in the US, more than 120,000 users had reported difficulties with Outlook, and later their number exceeded 130,000. The complaints concerned being unable to log into mailboxes, send or receive emails, and delivery delays. Anadolu cited different figures for the US: over 97,000 reports about Outlook, more than 38,000 about Microsoft 365, and around 4,500 about Teams — the site collects user reports, which do not necessarily reflect the actual number of affected people.
Which services were affected
In addition to email, according to TechCrunch, the Teams video conferencing service, the SharePoint file-sharing platform, the Copilot AI assistant, and the Defender XDR security system were unavailable. Individual users could not access OneDrive storage, Office for the web, and a number of other services. Microsoft initially reported complaints about access to Exchange Online mailboxes via various connection methods in countries of the Americas. The BBC noted that at around 6:30 PM GMT users in the United Kingdom were also reporting a spike in problems.
Cause and recovery
The company initially did not name a specific cause, reporting only 'elevated load' on part of its infrastructure and traffic redistribution across its global network. Microsoft later clarified that the elevated load was not caused by an increase in traffic, but by the fact that 'a large number of servers unexpectedly became unavailable,' which put strain on the remaining infrastructure. According to Anadolu, the company suspended all deployments, rerouted traffic away from the affected infrastructure, and restarted the impacted servers. In an update at 7:50 PM GMT, Microsoft said it was testing a configuration that caused servers to fail automated health checks and become unavailable; all affected servers had been restarted. The company published updates in the admin center (which was itself unavailable) and on X under incident numbers EX1550543 and MO1550821. The publications did not report full resolution of the consequences or a final estimate of the number of affected users.
Second major outage in a few months
This is already the second major Microsoft 365 incident in a short period: in September 2026, an outage of the online suite of services, including Outlook, lasted several days, and the company then attributed it to a 'baseline authentication configuration' issue that prevented users from accessing the service. In October, according to euronews, Microsoft also offered around 60,000 employees voluntary severance payments — these events are not directly related, but they show that during this period the company was operating under heightened scrutiny of its infrastructure and personnel policies.
Image source, Reuters 
