A massive Microsoft outage is causing disruption across the world for airlines, banks, and retailers

• A mass IT outage is affecting flights, banks, and critical infrastructure around the world.
• The issue was caused by a 'defect' in a Windows update, cybersecurity firm CrowdStrike said.
• Crowdstrike and Microsoft have said that a fix has been deployed

Major airlines, banks, and supermarkets are experiencing widespread disruptions linked to an IT outage after Microsoft reported problems linked to an issue at cybersecurity firm CrowdStrike.

American Airlines and United Airlines issued advisories to be relayed to the carriers' airborne flights early Friday morning. People were being issued with handwritten boarding passes at airports because of the disruption, which was caused by an update to the Windows operating system.

They said communication was intermittent as they were experiencing issues with systems like the Aircraft Communications Addressing and Reporting System, or ACARS, which transmits messages to planes often from air traffic control or airline operations.

At Heathrow, travelers were advised to check their gate numbers on Google as information screens were not working.

911 lines, broadcasters, and fast-food outlets are among those affected, as are grocery stores, retailers, and fast-food giants whose in-store cash registers malfunctioned.

As commuters woke up in New York City, they were warned that much of the train arrival information on the Subway would not be available, though the train service was unaffected.

"The world grinding to a halt because of a global IT meltdown shows the dark side to technology and that relying on computers doesn't always make life easier," said Dan Coatsworth, an investment analyst at AJ Bell.

CrowdStrike CEO George Kurtz posted to X on Friday, saying the company was "actively working with customers impacted by a defect found in a single content update for Windows hosts."

"The issue has been identified, isolated and a fix has been deployed. We refer customers to the support portal for the latest updates and will continue to provide complete and continuous updates on our website," he added.

Microsoft acknowledged the issue in an X update on Friday morning, writing, "Our services are still seeing continuous improvements while we continue to take mitigation actions."

One expert told BI there was no automatic or remote solution to the problem , meaning "every computer affected has to have some manual interaction."

Multiple airports and airlines are warning of disruptions and delays

In Singapore, Changi Airport — one of the world's busiest airports — said it was manually checking in the passengers of some airlines. Local media reports show long queues at Changi Airport's check-in counters.

A spokesperson for Singapore's Changi Airport told BI: "Due to a global outage affecting IT systems of many organizations, the check-in process for some airlines at Changi Airport is being managed manually."

This included the "issuance of boarding passes," the spokesperson said.

At Luton Airport, near London, Nick Xydias, told Business Insider he was stuck waiting for a Wizz Air flight to Larnaca, Cyprus.

"It's my birthday, and we'd booked a romantic trip with my wife. She'd got a new dress and everything," he told Business Insider from a winding and frustrated line of passengers. "All the flights are grounded."

He also shared these photos:

In Australia, Melbourne Airport said it was experiencing a "global technology" issue impacting check-in procedures for some airlines. Sydney Airport also reported a global outage affecting airline operations and terminal services, although flights were still arriving and departing the facility.

Delhi Airport in India also said it was impacted. A passenger at the Rajiv Gandhi International Airport wrote on X that he had been issued a hand-written boarding pass.

Edinburgh Airport in the UK and Berlin Airport in Germany also warned of delays.

Ryanair, Europe's largest airline, warned of "disruption across the network due to a Global 3rd party IT outage which is out of our control" and is advising passengers to head to the airport early.

On Thursday night, Frontier Airlines issued a ground stop order, saying in a statement: "flight operations are currently being impacted by a major Microsoft technical outage."

CrowdStrike issues

Many of the affected Windows devices displayed an error message — colloquially called the "Blue Screen of Death" — that locks users out of their computers.

An update released by cybersecurity firm CrowdStrike is believed to have caused the issue. It's unclear if the outage is directly related to Microsoft's systems.

The Austin-headquartered tech giant, which specializes in security for cloud computing platforms, confirmed with CNBC on Friday morning that it was receiving outage reports.

"CrowdStrike is aware of reports of crashes on Windows hosts related to the Falcon Sensor," CrowdStrike wrote in a message, per CNBC. The Falcon is one of the company's landmark cybersecurity products.

A Reddit forum moderator from the company posted shortly after the outage, saying CrowdStrike was investigating the issue.

"We have widespread reports of BSODs on Windows hosts, occurring on multiple sensor versions," the post said.

CrowdStrike's press team did not immediately respond to a request for comment sent outside regular business hours by Business Insider.

The outage is "one of the most significant of cyber issues of 2024," Omer Grossman, the chief information officer at cybersecurity company CyberArk, said in a statement to BI. "The damage to business processes at the global level is dramatic."

He said the glitch came from a software update for CrowdStrike's endpoint detection product.

"A malfunction in this can, as we are seeing in the current incident, cause the operating system to crash," Grossman said.

This is a developing story. Please check back for updates.

Correction: July 19, 2024 — An earlier version of this story gave the wrong destination airport for a passenger. Nick Xydias was trying to reach Larnaca, Cyprus, not Monaco.