A major IT outage has taken down Windows computers around the world, knocking websites, airports and banks offline and leaving engineers scrambling to reboot systems.
The problem began in the early hours of Friday UK time, when staff noticed their computers crashing, displaying the so-called “blue screen” and going into recovery mode.
As businesses around the world struggle to get online, here’s what we know so far about the issue.
What happened and why did Windows go down?
Hundreds of thousands of computers suddenly shut down around the world, affecting businesses, transportation and television broadcasts worldwide.
The cause appears to be a software issue with a cybersecurity technology called CrowdStrike, which is used to protect against hacking threats, but engineers quickly concluded that the cause of the massive outage was a system problem.
The issue appears to be primarily affecting PCs running Microsoft’s Windows 10 software.
Who was influenced?
That’s a lot of people. We don’t yet know the full impact of this bug, but as of this morning we’ve seen TV stations, transport organisations and banks complaining about the problem.
Sky News was forced to cancel its morning show and replace it with pre-recorded footage, and Ryanair warned on its website that it could expect significant delays at airports around the world.
Images posted to social media showed computers at airports and transport hubs displaying the infamous “blue screen” error, with users also reporting planes being stuck on the runway.
Gatwick Express has warned passengers to expect sudden cancellations across the network.
Is it a cyber attack?
So far, all signs point to a problem with Crowdstrike’s software, but little is known about the underlying cause.
The technology is designed to protect computers from cyber incidents. As of 8 a.m., CrowdStrike had not disclosed the cause of the problem.
But on a Reddit forum used by Crowdstrike engineers and cyber experts, a user pointed to an update for customers, stating: “CrowdStrike is aware of reports of Windows host crashes related to Falcon Sensor. Symptoms include hosts experiencing bugcheck\blue screen errors related to Falcon Sensor.”
What is Crowdstrike and who owns it?
Crowdstrike is one of the world’s largest cybersecurity technology companies, valued at over $80 billion, and its tools are used by businesses around the world.
The flagship technology is known as endpoint detection and response, a type of antivirus used to combat hacking threats.
These products are regularly updated to address potential new cyber threats and often add new tools to your PC automatically.
Cybersecurity expert Troy Hunt added in a post on X (formerly Twitter) that CrowdStrike’s tools often have “privileged” access on PCs, meaning they can exert extensive control over the machine in order to eliminate threats.
But, he added, “It also means that if something goes wrong with the update, it could cause catastrophic damage to your machine.”
CrowdStrike is listed in New York and is owned by technology investors and big funds such as BlackRock.
Are the trains running today?
Network Rail has warned passengers to expect lengthy delays and cancellations across the network this morning as the train company deals with the impact of today’s IT outage.
A post on National Rail’s website warned: “This morning we are experiencing a network-wide IT issue affecting services across a number of rail operators.”
Avanti West Coast, Gatwick Express, Great Northern, Great Western Railway, Hull Trains, London Northwestern, Lumo, Northern, Southern, Thameslink, TransPennine and West Midlands are all affected.
⚠️ We are currently experiencing a widespread IT issue across our network. Our IT team is actively investigating to determine the root cause of the issue.
Driver diagrams may not be accessible in certain locations and last minute cancellations may occur.
— Thameslink (@TLRailUK) July 19, 2024
“There is currently an IT issue across our network,” National Rail said. “Our IT teams are investigating to determine the root cause of the issue.”
“As a result, some train operators may not be able to access driver diagrams in certain locations, which could result in trains being cancelled at short notice.”
“Other key systems, including our real-time customer information platform, are also affected.”
Why is Sky News down?
Sky News viewers might have been expecting a morning breakfast show this morning.
But when people tuned in this morning, the normal broadcast had been replaced with an error message: “We apologise for the disruption to broadcast. Sky News service is expected to be restored shortly.”
“Obviously not on air, but we’re trying our best,” host Jackie Bertoio said on Twitter.
Sky’s regular broadcast was replaced with a series of archive video and pre-recorded news reports. The problem also affected other broadcasters around the world, including Sky’s international division and ABC.
Expand your horizons with award-winning British journalism. Try The Telegraph free for 3 months and enjoy unlimited access to our award-winning website, exclusive apps, great offers and more.