CrowdStrike update causes global IT outage

A faulty software update has caused one of the biggest IT outages in history, grounding flights, disrupting hospitals and taking television channels off air around the world.

The problem began early on 19 July, when the cyber security company CrowdStrike sent an update to computers running Microsoft Windows. Millions of machines crashed and displayed the "blue screen of death".

What went wrong?

CrowdStrike's Falcon software is used by many large businesses to protect their computers from cyber attacks. It runs at a deep level of the Windows operating system, so a fault in it can stop the whole computer from working.

The company said a defect in a content update caused the problem, and that it was not the result of a cyber attack. It withdrew the update, but many affected computers had to be fixed by hand, one at a time.

Microsoft later estimated that around 8.5 million Windows devices were affected.

Chaos in Britain

In Britain, many GP surgeries were unable to use their appointment and prescription system, and some hospitals were affected. Train companies reported problems, and airports, including Birmingham, saw delays as airlines were forced to check in passengers by hand.

Sky News was taken off air for several hours, and some shops and businesses were unable to take card payments.

Around the world

Thousands of flights were cancelled around the world, particularly in the United States, where several major airlines grounded their planes. Banks, stock exchanges, broadcasters and emergency services were also affected.

Apologies

CrowdStrike's chief executive, George Kurtz, apologised for the disruption and said the company was working with customers to restore their systems. Shares in the company fell sharply.

Lessons

The outage has highlighted how much the world depends on a small number of technology companies. A single mistake in one piece of software was enough to disrupt services across the globe.

Experts say organisations need better plans for dealing with technology failures, and that software companies must test their updates more carefully before releasing them. Governments in several countries have said they will look at what happened.

By the end of the day, many services were recovering, but businesses warned that it could take days to fix every affected computer.