A huge tech glitch caused chaos Friday around the world, all because of a mistake by CrowdStrike, one of the big cybersecurity companies. The error made many computers freeze up and show a “blue screen of death.”

CrowdStrike said they made a mistake while updating their software for Windows computers. According to a statement released by the company, “a bug is to blame” for missing a problem with some of the data in their update file. That bug meant the faulty data was not noticed until it was too late.

The glitch affected many people. The problem hit banks, hospitals, and airlines. It caused some 8.5 million Windows computers to crash, leading to a lot of disruptions. The company boss, George Kurtz, apologized for the trouble caused by this outage.

CrowdStrike has assured that they will enhance their testing methods to ensure that this does not repeat again. It will much improve the testing of its software and be more alert while checking for any problems before reaching users.

Experts, however, were less than impressed. Cybersecurity consultant Daniel Card wrote that CrowdStrike didn’t have proper safeguards in place to prevent this kind of failure. Another cybersecurity expert, Kevin Beaumont, mentioned that one big mistake CrowdStripe made was updating all its customers at once with its new software.

On the other hand, Sam Kirkman from NetSPI, another cybersecurity company, believes that CrowdStrike had done things to prevent this and, more to the point, that they normally stop problems.

The outage had tremendous financial implications. According to research by the insurance carrier Parametrix, the top 500 US companies-excluding Microsoft-lost an estimated $5.4 billion due to the outage. Of this amount, only between $540 million and $1.08 billion was insured.

The US government is now investigating how Delta Airlines handled the outage. Delta was compelled to scrub a great number of flights, which inconvenienced fliers. The worst of this hit is now over, according to Delta’s CEO, Ed Bastian, and things should recover soon.

Further, George Kurtz has been invited to testify before Congress about the event. The House Committee on Homeland Security intends to ensure there are better security measures for such tech issues moving forward. They have given CrowdStrike until Wednesday evening to reply and schedule a hearing.

The CrowdStrike error caused a worldwide tech outage, hitting millions of computers. The company is working on improving their testing to avoid future problems. The outage led to significant financial losses and scrutiny from the US government, with Delta Airlines and CrowdStrike facing tough questions.