Microsoft said on Thursday that efforts to repair a major outage of Outlook were not going as expected and the firm was seeking alternative solutions as users around the world were left without its crucial services.
The hours-long disruption, which Microsoft attributed to “elevated load” on its infrastructure, has hit email as well as products such as Teams and the AI assistant Copilot.
The impact of the outage has been felt globally, with users ranging from companies to governments reporting that they were unable to communicate via Outlook.
“We’ve monitored the status of the changes applied to improve serviceability and confirmed they’re not taking as expected,” Microsoft said on X.
“We’re identifying alternate workstreams that can be applied to increase capacity,” the tech giant added, without saying when service was expected to be fully restored.
The disruption went global within an hour, knocking out Microsoft products in 74 countries and territories, outage tracker Downdetector reported.
A map posted by Downdetector on X showed the outage affected users across the Americas and parts of Europe, Asia and Africa.
New Zealand embassies hit
One of the impacted countries was New Zealand, where the foreign ministry sent a notice saying its “ability to receive emails has been affected by the global Microsoft outage. This also impacts all New Zealand Embassies, Consulates and Representative Offices around the world.”
In New Zealand, the disruption extended well beyond government communications. Hospitals were forced to revert to fax machines and phone calls, immigration and visa processing was halted, and several government registers — including those for licensed building practitioners and electrical workers — went offline.
Root cause: servers overwhelmed
Microsoft initially said it was investigating outage reports “in the Americas,” but later confirmed that the issue apparently affected “Microsoft 365 service connectivity for users in any region.”
Microsoft 365 is the company’s cloud-based subscription service that includes popular applications such as Outlook and Teams.
“We’ve determined a portion of infrastructure is experiencing elevated load across multiple regions, which is likely contributing to the connectivity errors,” the company wrote on X.
“We’re aggressively pursuing all pathways to reduce impact,” it added.
Microsoft later clarified that the elevated load was not caused by a spike in user traffic. Instead, a large number of servers had become “unexpectedly unavailable” after failing automated health checks, shifting the burden onto the remaining infrastructure.
A core process on the affected servers was “becoming overwhelmed, which causes the servers to stop responding and contributes to the capacity loss,” Microsoft said.
The company confirmed the outage was not the result of a cyberattack or malicious activity. Copilot executive Charles Lamanna posted on X: “We regret that today’s outages caused disruptions for our customers… I can confirm that there is no indication that this is the result of malicious or cyber activity.”
A Microsoft spokesperson, Mark Gregory, told The Guardian the problem stemmed from “a misconfiguration in the network layer.” When servers with configuration issues drop out, “all of the users are trying to access the remaining servers, and that overloads them. And then they go down. And so you end up with a cascading problem.”
Nearly 130,000 reports at peak
Downdetector, which tracks online outages, showed a sharp decline around 0450 GMT in users’ reports of disruptions in Washington and Hong Kong.
At its peak, nearly 130,000 users in the United States alone reported issues with Outlook, according to Downdetector, with global reports topping 140,000 — more than 2,000 times the normal level. Thousands of users also reported issues with Teams and Copilot.
Widening circle of affected services
The disruption affected a far broader range of Microsoft products than initially apparent. Beyond Outlook and Teams, the outage hit SharePoint Online, Copilot 365, Microsoft Defender, Microsoft Intune, Microsoft Purview, Power BI, Microsoft Planner and Microsoft To Do. Consumer services including Word, Excel and PowerPoint on the web, as well as OneDrive, were also impacted.
Microsoft 365 connectors used by artificial intelligence companies OpenAI and Anthropic were also affected, with both companies reporting that their tools were not working as expected.
Recovery efforts stall
As the outage dragged on for hours, Microsoft posted a series of updates on X, detailing continued but unsuccessful efforts to restore full service.
In one update last night, Microsoft said it was “observing limited recovery” as it sought to route user traffic away from affected servers.
“As capacity is restored, users may experience a gradual recovery as their clients reconnect,” the company added.
However, hours later – Microsoft delivered a setback, saying its latest changes “are not taking as expected” and it was pursuing alternate workstreams to increase capacity.
The company said it had paused all deployments and configuration changes, moved traffic off affected infrastructure, restarted servers, and even reverted a recent network configuration change that correlated with the start of the disruption.
Yet servers that were brought back online became unresponsive again once traffic was reintroduced, complicating recovery efforts. Microsoft said it was temporarily limiting certain types of traffic to affected infrastructure in some locations and rebuilding a subset of servers using a previous configuration.
As of the latest updates on Friday morning, the incident remained unresolved, with Microsoft still working to restore full service more than 10 hours after the outage began.
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