All of United Airlines flights were grounded Sunday because of a computer outage, the Federal Aviation Administration said.

"A ground stop is in place for domestic flights due to an IT issue," United tweeted. "We're working on a resolution. We apologize for the inconvenience."

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The ground stop was lifted after 9 p.m.

"The ground stop has been lifted," United tweeted. "We're working to get flights on their way."

The Aircraft Communications Addressing and Reporting System, or ACARS, was having issues with low bandwidth, officials told NBC News.

International flights were not affected.

This is a developing story. Check back for updates.

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Savannah Chrisley, daughter of former reality TV stars Todd and Julie Chrisley, speaks outside the Federal Prison Camp on May 28, 2025, in Pensacola, Fla. President Donald Trump pardoned Todd and Julie Chrisley, who were found guilty of defrauding banks out of $36 million and hiding millions in earnings to avoid paying taxes. (Dan Anderson/AP)

Credit: Dan Anderson/AP