Travelers faced a big headache this morning when American Airlines grounded all U.S. flights for an hour due to a tech issue on one of the busiest travel days of the year.

In a statement, American Airlines blamed a “vendor technology issue” that messed with the systems needed to release flights for takeoff.

The Federal Aviation Administration (FAA) jumped in, showing that airports like Philadelphia International, Dulles, and Reagan National were dealing with deicing delays as well.

By 9 a.m., the FlightAware “Misery Map” showed 544 flights delayed and five canceled. Charlotte, North Carolina’s airport saw nearly 120 delays alone.

Not exactly what you want to see when you’re trying to catch a flight during the Christmas holiday.

Luckily, by 8 a.m., the FAA gave the green light and the ground stop was lifted.

If you were flying out that morning, though, you probably spent some time checking updates and praying your flight wasn’t one of the delays.