Updated on 19 July 2024: This story was updated with CrowdStrike’s confirmation of the issue in a blog post and the CEO’s apology in a statement made to the Today programme. You can watch that below.

A bug is affecting a large number of systems running Windows and the security software from CrowdStrike. Airlines, train companies, health and emergency services are among those facing an issue causing repeated restarts and the blue screen of death (BSOD).

Microsoft says of the issue: “We have been made aware of an issue impacting Virtual Machines running Windows, running the CrowdStrike Falcon agent, which may encounter a bug check (BSOD) and get stuck in a restarting state. We are aware of this issue and are currently investigating potential options Azure customers can take for mitigation.”

The issue appears to be caused by CrowdStrike’s Falcon Sensor agent, a part of its security platform. 

CrowdStrike says in a blog post that “the issue has been identified, isolated and a fix has been deployed.”

The effect of the bug is still being widely felt globally, however. The Falcon Sensor is commonly used to protect Windows machines and that’s evident by the number of companies, organisations and services reporting outages today.

UK news broadcaster Sky News was offline for the morning. It has since managed to restart its service. Though some companies will take longer to get up-and-running again, such as KLM, the major airline out of the Netherlands, which has had to suspend operations. Other airlines have reported disruptions, including Ryanair.

Various football clubs, airports, and banks have reported outages. London Gatwick has confirmed it is impacted by the outage but still recommends passengers arrive at a regular time for their flights. Berlin and Schiphol airport are both affected, though many are reporting they are operating as normal. 

A user on X suggests an airport in India has resorted to using hand-written boarding passes rather than the usual printed ones. 

There are reports of other airports facing major IT shutdowns and delays or cancellations. GP services in England are also said to be affected.

CrowdStrike admits this is a fault with “a single content update for Windows hosts” and “not a security incident or cyberattack.”

The issue may take some time to resolve fully. Systems in constant boot loops are a nightmare to troubleshoot, update, or rollback to previous updates, as many PC builders can surely attest to. No doubt we should think of the poor IT workers—they’re in for a long day. 

Microsoft engineers may be in for an especially rough patch, as a separate Microsoft 365 issue is leaving some users high and dry for access to 365 apps and services. This, however, is said to be caused by Microsoft’s own messing around, not an external service.

CloudStrike CEO’s apology

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“I want to start by saying we’re deeply sorry for the impact that we’ve caused for customers, travellers and anyone affected by this including our companies,” George Kurtz, CEO of CloudStrike, says in an interview with the Today programme.

“The system was sent an update. That update had a bug in it, and caused an issue with the Microsoft operating system. We identified it very quickly and remediated the issue.”

Kurtz goes on to explain that it is now working with its customers to try to get affected systems up-and-running. This is clearly take some time, as its customers include hospitals, emergency services, schools, and even US state governments. IT systems worldwide have been hit by the bug.

These systems are said to be stuck in a reboot/BSOD loop, which may prove tricky to update.

“It’s been a long night,” Kurtz says at one point during the interview, following what is looking to be one of the worst IT outages in history.

Even with systems returning, the clean-up from the outages is taking some time. There are thousands of passengers awaiting planes that never took off at airports and medical appointments that never took place. Those leave a backlog to deal with. The good news is that some airports are reporting that systems are back online and they’re getting back to normality.