After a widely used network security program crashed and Microsoft announced issues with its cloud services, many computer systems around the world malfunctioned on Friday, with the services of airlines, banks, and the London Stock Exchange paralyzed as a result.

On Friday, CrowdStrike warned customers that its Falcon Sensor product, which is responsible for monitoring threats, caused Microsoft Windows operating systems to crash. It is unclear what caused the issues, but Microsoft's Azure cloud and 365 services were also interrupted.

In a statement, Microsoft said it understood that the problem affecting Windows devices was caused by an update from a third-party software platform and that a solution was expected to be available soon.

There have been few interruptions of this size in recent years. "This is unprecedented," said Alan Woodward, a network security professor at the University of Surrey, to Bloomberg. "The economic impact will be huge."

Please check the real-time blog about the service interruption.

Passengers wait for delayed United Airlines flights at Los Angeles International Airport on July 19th.

On Friday, major companies such as McDonald's, United Airlines, and the London Stock Exchange Group (LSE Group) all announced different problems with their customer service.

As a result of global IT faults, planes were unable to take off, and many airports were in chaos. Many airlines experienced unprecedented operational interruptions as the busy summer season approached.

According to the Federal Aviation Administration's advisory webpage, Delta Air Lines and American Airlines stopped flights, except for United Airlines, due to communication issues. In Europe, Deutsche Lufthansa AG Sponsored ADR said it was disrupted, as did Air France and Ryanair.

An insider disclosed that some JPMorgan employees were unable to log into the company's system due to global IT faults on Friday.

A person requesting anonymity for discussing non-public information said the bank also told some buying clients that it was unable to process certain transactions. A JPMorgan spokesperson based in New York declined to comment.

Troy Hunt, an Australian security consultant and creator of the hacked auditing website Have I Been Pwned, posted on X, stating, "This will be the largest IT failure in history, and I don't think it's too soon to say that."

In a post on X, AGL Energy in Australia stated that it was experiencing system problems due to a CrowdStrike failure. After news of the failure broke, CrowdStrike's stock price fell as much as 14% in pre-market trading.

Mikko Hypponen, chief researcher at Finnish information security company WithSecure Oyj, said there was no evidence that CrowdStrike's problem was related to any network attacks.

CrowdStrike CEO George Kurtz also said that global IT service interruptions were not "network attacks," and that the company was "actively" working with affected customers.

The malfunction first appeared in the United States late on Thursday and was attributed to issues with Microsoft services such as Azure and 365. Frontier Airlines, a subsidiary of Frontier Group Holdings Inc., suspended flights for over two hours. The airline began to restore flights after cancelling takeoffs nationwide at 23:00 New York time.

The London Stock Exchange Group (LSE Group) that operates the London Stock Exchange stated it encountered a global technical issue that prevented news from being released.

In Asia, Japanese users began reporting problems with Microsoft 365 services in the afternoon. Airlines at Mumbai, Narita, Singapore, and Hong Kong airports began manually handling passenger check-in.

Microsoft said there had been reports of issues since it resolved Azure cloud service interruptions, several hours of problems with Azure and Microsoft 365 had been reported earlier on its status page.