Hundreds to thousands of businesses worldwide are still struggling following a faulty software update that caused global tech outages on Friday.

The outage, which brought the Blue Screen of Death to many Windows machines across the globe, disrupted operations at major banks, airlines, retailers, and other industries last week.

The outage came after Crowdstrike, a cybersecurity giant used by Microsoft, pushed a faulty security update. That update affected an estimated 8.5 million Windows devices, Microsoft noted in a blog post following the outage.

"While software updates may occasionally cause disturbances, significant incidents like the CrowdStrike event are infrequent. We currently estimate that CrowdStrike's update affected 8.5 million Windows devices or less than one percent of all Windows machines. While the percentage was small, the broad economic and societal impacts reflect the use of CrowdStrike by enterprises that run many critical services," the post read.

The outage led to the cancellation of thousands of flights in the US. Specifically, around 2,527 flights into, within, or out of the country were canceled by Sunday evening. Over 31,400 flights were also delayed, according to data from FlightAware.com.

By airline, Delta Air Lines had the most cancellations, with 1,057 flights canceled Sunday. The company also saw 1,729 of its flights delayed on the same day, the website showed.

Apart from large corporations, many small businesses also struggled with the outage. Some business owners were unable to pay their employees and vendors, while other businesses could not make phone calls or log on to their computers for work, per the Associated Press.

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What Caused the Global Tech Outage?

As of Sunday, it is still unclear what exactly caused the outage. Crowdstrike is known for producing antivirus software designed to prevent hackers from causing this type of disruption. In a statement posted on X (formerly Twitter), Crowdstrike CEO George Kutz said the issue "has been identified" and noted that a fix has been deployed. He did not give any further information on the issue.

"Today was not a security or cyber incident. Our customers remain fully protected," Kurtz added.

Although the fix has been deployed, Lukasz Olejnik, an independent cybersecurity researcher, told The Verge that the issue may still take "days to weeks" to resolve.

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