A disruption lasting more than 12 hours to Microsoft Outlook and Teams severely affected communications across businesses and government organizations worldwide on Friday. The outage forced some institutions to return to fax machines and led to the cancellation of at least one bond repurchase transaction in Europe.

Microsoft said server-related problems caused the disruption, which also affected its Copilot AI assistant. The company said it had begun a wider deployment of software fixes that was helping restore stability across its systems. It added that there was no indication of malicious activity. Outlook and Teams are among the world’s most widely used workplace applications, serving hundreds of millions of users. The disruption prevented people from carrying out essential tasks, including sending emails, managing calendars and conducting virtual meetings.

Government agencies in countries including Australia, Japan and the United States were affected. The incident also delayed operations at trading firms, disrupted the publication of financial results by some companies and prompted airlines to alert customers about delays in communication, according to public statements. Organizations running Microsoft services on their own servers rather than through its cloud infrastructure experienced relatively limited disruption.

ANOTHER DISRUPTION TO MICROSOFT SERVICES

The incident ranks among the longest outages in Microsoft’s history and marks the second major disruption to its services this year.

Microsoft said the problem primarily affected features connected to Exchange Online, its cloud-based email and calendar platform, while applications not dependent on the service continued to operate.

The outage has renewed concerns about the world’s dependence on a small number of major technology companies that provide both essential business software and the cloud infrastructure supporting it.

Microsoft shares declined 1.7% in premarket trading, underperforming the wider market. The stock has risen approximately 8% so far this year.

Josh Gilbert, a market analyst at trading platform eToro, said the latest disruption was concerning because it followed another Microsoft 365 outage earlier in the year. He warned that repeated reliability problems could encourage IT departments to reconsider placing more of their operations with a single provider.

However, some analysts have questioned whether such incidents would prompt customers to move to competing platforms, given the substantial costs involved in replacing software that is deeply integrated into everyday business activities.

Microsoft’s 365 services also experienced disruptions in January this year and October last year. In October 2025, the company reported an outage affecting its Azure cloud platform, which disrupted its productivity software and operations across several industries worldwide.

BUSINESSES TURN TO FAX TO CONFIRM TRANSACTIONS

A spokesperson for the UK government said officials were working with Microsoft to resolve the disruption, which affected organizations including the National Health Service (NHS) and London’s Metropolitan Police.

The Metropolitan Police said the loss of access to email and other services was affecting its ability to process certain crime reports submitted online. However, its capacity to respond to emergency calls remained unaffected.

The NHS said local healthcare services were adopting alternative arrangements, including using other IT systems and paper-based records.

The impact on businesses was extensive. European exchange operator Euronext reported email problems, British insurer Aviva activated backup arrangements for its earnings calls, and Danish shipping company Maersk cautioned customers about delays in receiving updates.

US artificial intelligence companies OpenAI and Anthropic also encountered problems with their Microsoft connectors. In India, airlines IndiGo, Akasa Air and Air India reported disruptions to their email-based customer support services.

The outage affected fund management operations at securities firms, life insurance companies and investment trust businesses in Taiwan. One company cancelled a bond repurchase transaction because of the disruption, according to a source familiar with the matter.

A second source said another Taiwanese financial institution had to use fax machines to confirm trades.

In the United States, electric truck manufacturer Workhorse Group postponed the release of its financial results, originally scheduled for Thursday, to November 16. Swiss luxury goods group Richemont also briefly delayed the announcement of its first-half results on Friday.

In Australia, several government organizations, including the country’s intelligence agency and federal police, were affected. Cyber Security Minister Tony Burke said Microsoft had indicated that it did not believe the incident was caused by a cyberattack.

Burke added that the disruption was primarily affecting email systems.