Sabre said on Monday it had fixed a technical issue that affected booking services of its U.S. airline partners such as Southwest Airlines, Virgin America, and JetBlue Airways.

Customers of these airlines were unable to book or modify existing reservations due to a temporary outage of Sabre’s computer systems.

A spokeswoman from Sabre sabr said the outage of a pricing engine impacting some of its airline and travel agent customers had been resolved and the systems were back in recovery mode.

“Domestic booking functionality on Southwest.com is back up and running at this time,” Southwest luv tweeted.

Virgin America va also tweeted saying they were facing a reservations system outage causing booking and check-in issues and that the problem had been resolved.

When contacted, JetBlue jblu said the tech issue had been resolved, and customers could now book flights or change existing reservations on the website, the mobile app or over the phone.

For more on JetBlue, watch Fortune’s video:

As airlines switch to electronic luggage tags and more travelers swap paper tickets for boarding passes stored on smartphones, industry consultants say the impact of technology disruptions will keep growing.

That means more money lost for airlines and more travel plans thwarted for passengers when a glitch occurs.

Earlier this year, Delta Air Lines dal canceled hundreds of flights and delayed many others after an outage hit its computer systems, grounding planes and stranding passengers of one of the world’s largest carriers at airports around the globe.

American Airlines Group aal flights were delayed in April last year because of an application problem on pilots’ iPads, which recently replaced paper flight manuals. Some planes returned to airport gates to access Wi-Fi and fix the issue.

This story has been updated.