A Microsoft 365 outage that began shortly after noon Eastern on November 12, 2026 was still unresolved nearly six hours later, with users reporting problems reaching Exchange Online mailboxes. Downdetector said there were more than 100,000 reported outages by about 1:30 p.m. Eastern.
Microsoft first said it was investigating access issues “through multiple connection methods in the Americas,” and then widened it: the problem “may affect Microsoft 365 service connectivity for users in any region.” The company tracked the incident under EX1550543 in the Microsoft 365 admin center.
What Microsoft says went wrong
The first explanation pointed at elevated load on “a portion of infrastructure” across multiple regions. Microsoft later ruled out a traffic spike and blamed a number of servers becoming unavailable unexpectedly, which strained the infrastructure still running.
Those servers were failing automated health checks, and Microsoft said its investigation indicated the failures may originate from “a specific component that’s responsible for processing server health.” By late afternoon, it said it had not identified any recent change correlated with the start of the outage.
What it has tried
The response moved in stages. Microsoft paused all deployments, shifted traffic off the affected infrastructure, and restarted affected servers.
Around 4 p.m. Eastern it validated an alternative service health check method, which let a subset of servers return to service, and it said it was applying that change more broadly. It also began preparing automated recovery systems to detect and restart unresponsive servers.
By 5 p.m. the company said its actions “have not provided the anticipated relief” and that it was opening all pathways to restore service, isolating part of the infrastructure and reintroducing traffic to confirm stability. Around 6 p.m., Microsoft said it was returning a portion of affected servers to service, and that they “remain stable so far.”
What it means for users
The outage started around 1:00 a.m. on November 13 in the Philippines, with users reporting trouble reaching Exchange Online mailboxes, though Microsoft warned the issue may affect connectivity in any region. Status updates are being posted to the admin center and the @MSFT365Status account.
The 4 p.m. update gave no count of the servers still affected, and the incident was ongoing as of the 6 p.m. Eastern update.
Source: Global News
Frequently Asked Questions (FAQ)
Access to Exchange Online mailboxes, with Microsoft warning the issue may affect Microsoft 365 service connectivity in any region.
Shortly after noon Eastern on November 12, 2026, which is about 1:00 a.m. on November 13 in the Philippines.
Microsoft says servers became unexpectedly unavailable and strained the remaining infrastructure, with failures traced to a component that processes server health. It ruled out a traffic increase.
Not as of the last update. Around 6 p.m. Eastern, Microsoft said a portion of affected servers had returned to service and remained stable so far.
In the Microsoft 365 admin center under EX1550543, and on the @MSFT365Status account.
Emman Tortoza
Emman has been writing technical and feature articles since 2010. Prior to this, he became one of the instructors at Asia Pacific College in 2008, and eventually landed a job as Business Analyst and Technical Writer at Integrated Open Source Solutions for almost 3 years.
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