For the second time in just over three months, United Airlines suffered a technical glitch that forced the carrier to ground all its domestic flights Sunday night. After over two hours, flights have resumed but there are still significant delays.

The company has issued travel waivers for passengers affected by Sunday’s delays. Customers who were booked to fly Jan. 22-23 can change their flights, without paying any fee or fare difference, if they book “new flights departing on or before Jan. 25, 2017, as long as travel is rescheduled in the same cabin (any fare class) and between the same cities as originally ticketed.​​”

There are a number of ways you can change your booking, including the check-in and reservations management pages on the website, by getting in touch with the airline’s contact center, using the United app, at an airport kiosk, or by speaking with an airline representative at the airport.

The unspecified computer problem did not affect the airline’s international operations, or its subsidiary carrier, Continental.

It is somewhat ironic that less than a week ago, when releasing its fourth quarter and full year financial results for 2016, United said it “achieved best full-year on-time performance while reporting the lowest number of cancellations, delay minutes and mishandled bags in company history.”

Flyers who were affected by the delay took to social media to berate United Airlines.

Someone also used the opportunity to poke fun at the new White House Press Secretary Sean Spicer.

A computer glitch in October 2016 grounded United Airlines flights around the world.