Microsoft Says Network Upgrade Glitch Caused Outlook, Teams Outage, Rules Out AI Or Cyber Link

Microsoft has said the disruption affecting Outlook, Teams and other Microsoft 365 services was caused by a technical issue linked to an earlier network capacity upgrade, ruling out any malicious or cyber activity.

In an update on the outage, Microsoft's Executive Vice President for Copilot, Agent and Platform, Charles Lamanna, said the company was seeing “encouraging recovery progress”, with service availability and email delivery performance improving across an increasing portion of the affected infrastructure.

The company said it had addressed the underlying issue and was working to restore services for the remaining customers and regions. It also clarified that the incident was not related to cyber activity or artificial intelligence (AI) and agents.

Microsoft explains cause of outage, rules out cyberattack

Microsoft said the issue was introduced during an earlier network capacity upgrade and surfaced following a recent network change. The company said its teams were reviewing the incident and examining steps to prevent similar disruptions in the future.

We’re seeing encouraging recovery progress, with service availability and email delivery performance improving across a growing portion of affected infrastructure. We know our customers rely on our services to get important work done every day, and regret the impact these outages had on those who depend on us. We will continue to share more information as we have it, and for now we can confirm that there is no indication this is the result of malicious or cyber activity. Our teams are reviewing what happened and how we can prevent similar issues going forward.

— Microsoft (@Microsoft) November 13, 2026

It added that services were restored gradually because of the scale of demand, with stability checks carried out at each stage. While this extended the recovery process, Microsoft said the approach helped ensure a stable restoration.

Outlook outage affected users across 72 countries

The disruption, which began on Thursday, affected access to Outlook, calendar functions and workplace communication tools, including Teams.

At least 43,000 users across 72 countries reported problems accessing Outlook within an hour, according to outage-tracking website Downdetector. Complaints also increased across several European countries as users began their day.

The outage disrupted businesses and government agencies, highlighting the widespread dependence on Microsoft's cloud-based services and the impact that problems with a single infrastructure provider can have on users and organisations worldwide.

Microsoft apologises, promises detailed report

Microsoft apologised to customers and partners for the disruption, acknowledging that users rely on its services for important everyday work.

“We are deeply sorry for the disruption this incident has caused our customers and partners. We know the trust they place in our services and take that responsibility extremely seriously,” the company said.

We are deeply sorry for the disruption this incident has caused our customers and partners. We know the trust they place in our services and take that responsibility extremely seriously. We are seeing broad recovery and stability across our services. This was a technical issue not related to cyber or AI / agents. The incident was introduced by an issue during an earlier network capacity upgrade that surfaced following a recent network change. We have addressed the underlying issue and continue to restore service to remaining customers and regions. Given the scale of demand, we restored services gradually, validating stability at each stage. While this took longer, it helped ensure a stable restoration. We will provide a full post-incident report once our review is complete.

— Microsoft (@Microsoft) November 13, 2026

It added that it was seeing broad recovery and stability across its services and would share further updates as more information became available.

Microsoft said it would publish a full post-incident report once its review was complete.