Microsoft 365 Suffers Outage For Several Hours

The company attributed the outage to a recent networking update.

Microsoft reported that a networking update caused Microsoft 365 services to "intermittently fail" for some users Tuesday evening, Eastern Time.

As of 12:04 a.m., Wednesday, Microsoft said it had "confirmed restored access and functionality for all Microsoft 365 services."

[Related: The 10 Biggest Cloud Outages Of 2019 (So Far)]

Microsoft 365 includes Office 365 applications such as Outlook, Teams, Skype for Business, Exchange Online and Sharepoint Online.

The outage appears to have begun around 8 p.m., Eastern, based on reports on downdetector.com. The reported incidents peaked at about 8:18 p.m., around the time that Microsoft acknowledged in a tweet that it was "investigating an issue preventing access to Microsoft 365 services."

At 8:53 p.m., the company said in a tweet that "we've identified that multiple Microsoft 365 services are affected and we're actively looking for the swiftest means of restoring access."

An outage map on downdetector.com showed the Microsoft 365 outage affecting users in parts of the U.S., Canada, Asia and Australia.

The Microsoft 365 health status web page eventually indicated that a "recent networking update" had been responsible for the outage, GeekWire reported.

Microsoft opted to roll back the networking update to restore Microsoft 365 services. Just before 10 p.m., Microsoft tweeted that "we've identified and reverted a networking build that caused user traffic from the internet to Microsoft 365 services to intermittently fail, and are seeing early signs of recovery."

The outage was fully resolved just after midnight, Microsoft said.

We've confirmed restored access and functionality for all Microsoft 365 services. Please see MO196220 in the admin dashboard for final details of the event.

— Microsoft 365 Status (@MSFT365Status) November 20, 2019

In January, Microsoft saw two outages affecting some users of Office 365—one of which Microsoft blamed on DNS provider CenturyLink, which acknowledged a software defect affecting connectivity to customers' cloud resources.

In May, several core Microsoft cloud services, including compute, storage, Active Directory and SQL database services, were impacted by a nearly three-hour DNS outage. Some of Microsoft's cloud-based applications, including Microsoft 365, Dynamics and Azure DevOps, were also impacted.