World brought to a halt by drastic Microsoft outage with computers showing ‘blue screen of death’

Flights have been cancelled and TV stations have been taken offline in a drastic computer outage.

Windows PCs on Friday inexplicably started showing a “blue screen of death” error that left them unusable.

That led to problems at many of the world’s biggest companies, including airlines, TV stations and banks. Thousands of flights were cancelled, hospitals were forced to postpone appointments, and billions of dollars was wiped off the value of companies.

Issues had been found across the world, according to cyber security companies. The widespread outages led to responses from the US, UK and other governments.

The problem appears to relate to a broken cyber security update that left computers unable to start up.

Microsoft and others pointed the blame at CrowdStrike, a cyber security firm that offers software intended to protect computers from attack. A defective update had been pushed out to users that left those computers unable to turn on, its chief executive George Kurtz said.

Both CrowdStrike and others confirmed that the chaos was the result of a mistake rather than an intentional cyber attack. It also said the issue was only affecting Microsoft devices, not Mac or Linux computers.

TV stations were taken offline, airports are unable to check in flights, trains were disrupted and banks warned that customers might not be able to make payments.

Tracking website Down Detector registered outages and problems at a huge array of companies: Delta Airlines, Visa, Mastercard, Lloyds Bank, Santander, Amazon, RyanAir, Sky News, Ladbrokes, BT, and Microsoft Teams all show issues. It is not clear whether all of them are linked to the problem with PCs.

Delta, United and American airlines were all grounded in the US, according to the Federal Aviation Authority. Around the world, flights and train operators were hit by problems.

Govia Thameslink Railway – the UK’s busiest train operator, which runs the Southern, Thameslink, Gatwick Express and Great Northern services around London – said that it was experiencing “widespread IT issues”. RyanAir said it was a “global third party IT outage” and advised travellers to arrive “at least three hours before” their flights.

Even the London Stock Exchange suffered disruptions, and stock markets dropped on the outage. The FTSE 100 fell 0.8 per cent, seemingly as investors worried about the potential financial implications if the outage continued for a long time.

“We are currently experiencing widespread IT issues across our entire network,” it said. It meant that trains might be cancelled at short notice and that there would be issues getting real-time information to customers.

In both the UK and US, hospitals and other healthcare organisations said that the computer systems had left them unable to offer usual appointments. Some instructed patients to go home until the problems were resolved.

On Sky News in the UK, viewers were shown an error message that indicated the transmission had gone down.

“We apologise for the interruption to this broadcast,” it read. “We hope to restore the transmission of Sky News shortly.”

The trouble appears to relate to an issue at Crowdstrike, a cyber security company, which may have released a problem update. It said early in the morning that it had identified the issue and rolled the update back – but those computers that were already affected do not appear to have been fixed.

On the company’s Reddit thread, representatives advised that the problem could be fixed by deleting the update and then restarting the computer. That requires administrators to have access to the computer, however, which may not be immediately possible for those that are being used remotely.

On X, formerly known as Twitter, CrowdStrike said it had found a fix for the problem and specifically said that it was not the result of a cyberattack.

“CrowdStrike is actively working with customers impacted by a defect found in a single content update for Windows hosts. Mac and Linux hosts are not impacted,” wrote George Kurtz, the company’s president and chief executive. “This is not a security incident or cyberattack. The issue has been identified, isolated and a fix has been deployed.

“We refer customers to the support portal for the latest updates and will continue to provide complete and continuous updates on our website. We further recommend organizations ensure they’re communicating with CrowdStrike representatives through official channels.

“Our team is fully mobilized to ensure the security and stability of CrowdStrike customers.”

The outage also coincided with a separate issue at Microsoft 365, which appears to have been the result of problems with its Azure services cloud computing platform. That began late on Thursday, and Microsoft said on Friday afternoon that it had been resolved.