A major disruption in Microsoft’s server infrastructure has knocked Outlook, Teams, Copilot and several other services offline across 74 countries and territories. With governments, healthcare providers and businesses affected, Microsoft says there is no evidence of a cyberattack, but the root cause remains unclear.
Microsoft is struggling to fully resolve a major global outage affecting its workplace applications, including Outlook, Teams and Copilot, even as services begin returning for some users. The disruption, which started on Thursday afternoon (November 12), continued into Friday (November 13), impacting users across 74 countries and territories.
While some users have reported regaining access to Microsoft’s services, the company has yet to restore normal operations for everyone. Its recovery efforts have faced repeated setbacks, with servers brought back online overnight crashing again when traffic returned.
Microsoft acknowledged that its attempted fixes were delivering limited results, describing the progress as “marginal success”. The company is yet to identify the precise root cause of the disruption.
The outage has also highlighted the world’s growing dependence on a handful of technology giants for essential digital infrastructure, with businesses, government agencies and healthcare providers among those affected.
According to Downdetector, a website that tracks service disruptions through user reports, nearly 140,000 complaints were registered about Outlook alone. The list of affected services has expanded beyond email and communication tools to include SharePoint Online, Microsoft Defender XDR, Planner and To Do.
Microsoft 365, whose applications are used by more than 430 million people, is at the centre of the disruption.
More from BusinessWho has been affected by the Microsoft outage?
The impact has extended across multiple sectors and countries.
In the UK, several GP practices asked patients to contact them by phone for urgent queries instead of relying on emails or online forms.
The Singaporean government and Australia’s intelligence agency also reported disruptions. Meanwhile, AI companies OpenAI and Anthropic experienced problems with tools connecting their services to Microsoft 365.
US electric vehicle manufacturer Workhorse was forced to postpone its earnings call until Monday because of the disruption.
What went wrong with Microsoft’s servers?
Microsoft has not disclosed the precise technical cause of the outage, but its explanations have pointed towards problems within its server infrastructure.
Initially, the company attributed the disruption to “elevated load”, suggesting that its servers were experiencing unusually high pressure. However, it later clarified that the problem was not caused by a sudden surge in user traffic.
Instead, a large number of servers unexpectedly became unavailable, forcing the remaining operational machines to handle their workloads.
Investigations subsequently focused on Microsoft’s automated server health checks. These systems determine whether individual servers are functioning properly and can safely handle incoming traffic.
Microsoft said it was testing a configuration change to address an issue that was causing servers to fail these checks and drop out of service.
However, its recovery attempts have not gone entirely as planned, with previously restored servers crashing again after traffic returned.
Is your Microsoft data at risk?
Despite the scale of the disruption, there is currently no indication that the outage is linked to a cyberattack or that customer data has been compromised.
Microsoft has said it has found no evidence of a cyberattack. However, the company has yet to establish and publicly disclose the underlying root cause.
A disruption in accessing Outlook emails, Teams conversations or documents stored on Microsoft’s cloud infrastructure does not automatically mean that the information has been lost or exposed.
The immediate concern remains service availability rather than data security.
However, the outage raises broader questions about the resilience of cloud infrastructure and the risks associated with relying heavily on a handful of technology providers.
From healthcare providers and government agencies to multinational businesses, the disruption demonstrates how a technical failure within one technology ecosystem can have consequences across multiple countries.
While services are gradually returning for some users, Microsoft’s challenge is far from over. The company must restore normal operations across its platforms and establish what caused such a widespread failure in the first place.
