A widespread Microsoft 365 disruption struck enterprise users on Thursday, Nov. 12, 2026, shutting down access to Outlook email, Teams, and Copilot tools during the middle of the workday.
Global Server Outage Hits Business Applications
The technical failure blocked users across multiple regions from loading inboxes and connecting to cloud workplace applications, TechRepublic reported. Downdetector registered more than 130,000 problem reports for Outlook shortly after 1 p.m. Eastern Time, alongside tens of thousands of complaints involving Exchange Online, Teams, and Microsoft 365.
We're returning a portion of affected servers to the service, and they remain stable so far. We're also shifting traffic to alternate routes wherever possible and observing limited recovery. In parallel, we've streamlined the process of returning the remaining affected servers to…
Reuters figures cited by tracking services showed Downdetector recorded more than 130,000 Outlook problem reports around 1:27 p.m. ET. More than 46,000 reports involved Microsoft 365, and about 3,000 involved Teams. Those statistics represented user-submitted reports rather than verified headcounts of impacted people.
The company server status page indicated that users might encounter difficulties accessing Microsoft Exchange Online, Microsoft Teams, SharePoint Online, Microsoft Copilot 365, and Microsoft Defender XDR. Some users of Google Workspace (formerly G Suite) reported trouble accessing their Google-hosted email through Outlook desktop and mobile email clients.
We determined the elevated load isn't driven by an increase in traffic, but by a number of servers being unexpectedly unavailable; straining the remaining infrastructure. We're working to safely return them to service. More info under EX1550543 and MO1550821 in the Microsoft 365…
Service advisories said affected infrastructure components failed automated health checks, causing servers to drop offline unexpectedly. The resulting traffic surge overwhelmed remaining systems rather than an increase in overall customer volume. The disruption arrived two days after Microsoft rolled out its November Patch Tuesday updates, which resolved 1,094 vulnerabilities across its product lineup.
Among them was CVE-2026-124194, an Outlook spoofing flaw that attackers have exploited, which can compromise a user authentication credentials if they open a specially crafted file in a vulnerable Outlook client. Microsoft tracked the Exchange Online disruption under EX1550543 and the wider Microsoft 365 incident under MO1550821 within the Microsoft 365 admin center, listing both as service degradations just before 3 p.m. ET.
We're investigating reports of users experiencing issues accessing Exchange Online mailboxes through multiple connection methods in the Americas. More details can be found in the Microsoft 365 admin center under EX1550543.
Engineers Deploy Emergency Server Mitigations
Microsoft deployed emergency mitigations throughout the afternoon, testing configuration changes and restarting unresponsive hardware. Engineers rerouted connection traffic across worldwide infrastructure to balance operational loads. In an update just before 3 p.m. ET, the company said affected servers were failing automated health checks and that it was testing a workaround to bypass the specific component responsible for executing those checks while also investigating elevated processor usage on those systems.
At the time of publishing, the company was still investigating what triggered the failures and had disclosed no evidence of a cyberattack. The outage tracking service also registered more than 46,000 reports involving Microsoft 365 and about 3,000 involving Teams.
“We’re aggressively pursuing all pathways to reduce impact,” the company said in an update on X. In a subsequent update on X, the company acknowledged that its earlier efforts failed to restore service, saying, “We’re opening all available pathways to restore service, as our actions taken thus far have not provided the anticipated relief.” The company also said: “We’ve confirmed the issue may affect Microsoft 365 service connectivity for users in any region, more information will be provided in the Microsoft 365 admin center under EX1550543.” Furthermore, Microsoft said: “We’ve begun redistributing connection traffic across our worldwide infrastructure to help balance the load.”
Operations personnel paused all deployment schedules and configuration alterations while reviewing recent updates for potential correlation to the failures. Microsoft reported that some systems came back online later in the evening with stable performance indicators.
We've validated an alternative service health check method, which allowed a subset of affected servers to successfully return to service. We're now applying this change more broadly. We're also preparing automated recovery systems to continually detect and restart unresponsive…
In an update shared on Thursday at 6:23 p.m. ET / 3:23 p.m. PT, Microsoft said that it was bringing some servers back online, saying that “they remain stable so far” and that users should expect a “gradual recovery.” The company added in the same update: “We’re also shifting traffic to alternate routes wherever possible and observing limited recovery.”
We’re opening all available pathways to restore service, as our actions taken thus far have not provided the anticipated relief. We found a core process on affected servers is becoming overwhelmed, causing capacity loss. To validate a potential recovery, we're isolating a portion…
More on Microsoft
While we're working to mitigate impact, we've confirmed the issue may affect Microsoft 365 service connectivity for users in any region, more information will be provided in the Microsoft 365 admin center under EX1550543.
We've determined a portion of infrastructure is experiencing elevated load across multiple regions, which is likely contributing to the connectivity errors. We're providing more information under EX1550543 and MO1550821 in the Microsoft 365 admin center, as well as…