‘Largest IT outage in history’ hits Microsoft Windows and causes global chaos

A global IT failure has caused chaos at airports, banks, healthcare services and businesses around the world after a faulty software update triggered “the largest IT outage in history”.

Microsoft’s Windows operating system was at the centre of the outage, after it was hit by a faulty software update from the US cybersecurity firm CrowdStrike that left large numbers of workers facing an error screen labelled the “blue screen of death” as their computers failed to start. Experts said the recovery could take days because every affected PC may have to be fixed manually.

In the UK, Whitehall crisis officials were coordinating the response through the Cobra committee that deals with matters of national emergency or major disruption. Ministers were in touch with their sectors to tackle the fallout from the IT failure, and the transport secretary, Louise Haigh, said she was working “at pace with industry” after trains and flights were affected .

A Microsoft spokesperson said: “We’re aware of an issue affecting Windows devices due to an update from a third-party software platform. We anticipate a resolution is forthcoming.”

CrowdStrike confirmed the outage was due to a software update from one of its products and was not caused by a cyber-attack.

Troy Hunt, a leading cybersecurity consultant, said the scale of the IT failure was unprecedented.

“I don’t think it’s too early to call it: this will be the largest IT outage in history,” he wrote on X . “This is basically what we were all worried about with Y2K, except it’s actually happened this time.”

Among the affected firms was Ryanair, Europe’s largest airline, which said on its website: “Potential disruptions across the network due to a global third party system outage … We advise passengers to arrive at the airport three hours in advance of their flight to avoid any disruptions.”

In the US, flights were grounded owing to communications problems that appear to be linked to the outage. American Airlines, Delta and United Airlines were among the carriers affected. Berlin airport temporarily halted all flights on Friday, while in Australia, Melbourne airport advised customers it was “experiencing a global technology issue which is impacting check-in procedures for some airlines”.

There had been more than 1,000 flight cancellations worldwide so far due to the IT failure, according to the aviation analysis firm Cirium.

A passenger at Gatwick airport, the UK’s second largest, described the scene at the travel hub as “bedlam”, with staff handing out water to those stranded.

GP practices in the UK said they were unable to access patient records or book appointments. Surgeries reported on social media that they could not access the EMIS Web system. It is understood that NHS hospitals and 999 services are unaffected by the outage. The National Pharmacy Association confirmed that UK services could be affected.

A spokesperson for Keir Starmer said they were unaware of the problem having any impact on government services.

She said the government recognised the impact it was having more broadly and the public should follow the advice of transport operators and others.

The prime minister did not attend the Cobra meeting as he was hosting the Ukrainian president, Volodmyr Zelenskiy, at a meeting of the cabinet at the time.

“We are certainly aware of the disruption this has caused to business and to those particularly looking to travel today. We are closely monitoring the situation and making sure the relevant industries can use the support we can provide,” the spokesperson said.

The Israeli health ministry said “the global malfunction” had affected 16 hospitals, while in Germany the Schleswig-Holstein university hospital in the north of the country said it had cancelled all planned operations in Kiel and Lübeck.

In the UK, Govia Thameslink Railway (GTR) – the parent company of Southern, Thameslink, Gatwick Express and Great Northern – warned passengers to expect delays. According to the service status monitoring website Downdetector, users in the UK were reporting issues with the services of Visa, BT, major supermarket chains, banks, online gaming platforms and media outlets. The Sky News and CBBC channels were also temporarily off air in the UK before resuming broadcasting.

In financial services, Metro Bank reported problems with its phone lines in the UK and Santander said card payments “may be affected”. Monzo said some customers were reporting issues, while some bankers at JP Morgan were unable to log on to their systems and the London Stock Exchange said there were problems with its news service.

Alan Woodward, a professor of cybersecurity at the University of Surrey, said the outage appeared to have been caused by an IT product called CrowdStrike Falcon which monitors the security of large networks of PCs and downloads a piece of monitoring software to every machine.

“The product is used by large organisations that have significant numbers of PCs to ensure everything is monitored. Sadly, if they lose all the PCs they can’t operate, or only at a much reduced service level,” said Woodward, who added that fixing the problem could take days.

“The major frustration is that to fix the issue will require manual intervention on every affected PC. That will mean enormous delays in recovering and hence disruption for days to come,” he said.

CrowdStrike’s president, George Kurtz, wrote in a post on X that the incident had been caused by a “defect found in a single content update for Windows hosts”. He added: “This is not a security incident or cyber-attack. The issue has been identified, isolated and a fix has been deployed.”