CrowdStrike says that it has deployed a fix after a defective software update led to widespread outages and massive real-world impacts to flights, health-care services and 911 systems.

Microsoft tech outages reported Friday led to widespread disruptions worldwide in an incident stemming from a defective software update from cybersecurity giant CrowdStrike.

The update led to a “blue screen of death” for many Windows users and reportedly led to massive impacts on real-world services, including more than 1,000 flights being canceled, health-care services being curtailed and 911 outages.

Microsoft said the outage stemmed from an update to CrowdStrike’s Falcon software.

Here are five things to know on the CrowdStrike-Microsoft outage.

Flights Canceled

The outage has led to massive impacts, including widespread flight cancellations. Multiple airlines reportedly asked the Federal Aviation Administration for a full ground stop on flights amid the outage. Flights from American Airlines, United and Delta were the hardest hit, according to reports. Nearly 1,400 flights have reportedly been canceled globally.

“The FAA is closely monitoring a technical issue impacting IT systems at U.S. airlines,” the FAA said in a post on X. “Several airlines have requested FAA assistance with ground stops until the issue is resolved.”

In a statement posted on X Friday morning, United said that “as we work to fully restore these systems, some flights are resuming. Many customers traveling today may experience delays.”

American Airlines said on X that it was able to “re-establish its operation” as of 5 a.m. EST.

Delta said on X that it “has resumed some flights after a vendor technology issue impacting airlines and businesses globally.”

Health Care, 911 Services Affected

A number of U.S. hospitals have curtailed services, including elective surgeries and other non-urgent visits Friday as a result of the outage. Hospitals affected include Mass General Brigham in Boston and Cincinnati Children’s Hospital Medical Center.

“A major worldwide software outage has affected many of our systems at Mass General Brigham, as well as many major businesses across the country,” Mass General Brigham said in a post on X. “Due to the severity of this issue, all previously scheduled non-urgent surgeries, procedures and medical visits are canceled today.”

Cincinnati Children’s Hospital said on X that “many of our Microsoft-based computer systems have been affected by the worldwide technology outage. Our teams are working hard to minimize disruption to patient care and system operations, and we are bringing systems back up as quickly as possible.”

Hospitals in countries including Germany and Israel have also reportedly seen services affected. NHS England disclosed impacts to health records systems. “The NHS is aware of a global IT outage and an issue with a GP appointment and patient record system,” NHS England said in a post on X.

Meanwhile, 911 systems in states including Arizona, New Hampshire and Alaska were reported.

Cause Of The Outage

In a statement on its “Windows Sensor Update,” CrowdStrike said that a “defect found in a single content update for Windows hosts” had been discovered. The outage has not been caused by a cyberattack, the company said.

In a post on X, CrowdStrike CEO George Kurtz (pictured) said that “our team is fully mobilized to ensure the security and stability of CrowdStrike customers.”

Fixes Deployed

In its statement, CrowdStrike said that it has identified and isolated the issue 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,” the company said.

Additionally, “we further recommend organizations ensure they’re communicating with CrowdStrike representatives through official channels,” the company said.

Microsoft Statement

In a post on X, Microsoft said the update to CrowdStrike’s Falcon software led to “an issue with Windows 365 Cloud PCs.”

“To fix this, users may restore their Windows 365 Cloud PC to a known good state prior to the release of the update (July 19, 2024),” the company said in the post on its Microsoft 365 Status account.

Microsoft also linked to CrowdStrike’s statement, noting that CrowdStrike is “communicating to its customers directly through their support portal.”