“Earlier tonight we experienced an issue with our weight reporting system, which caused system wide flight delays,” the airline said in a statement on its Twitter feed late on Thursday in the United States.

“We have resolved the issue and are working to get customers to their destinations as soon as possible. We apologize for the inconvenience.”

Passengers said they had been forced to wait onboard planes or inside terminals as flights were delayed for several hours.

“On the plane for more than an hour, away from the gate and no communication. What’s happening?,” one passenger tweeted.

https://twitter.com/tipactim/status/786837404904747008

In Paris, passengers complained as check-in lines grew for a flight to New York, a Reuters reporter said on Friday morning.

The airline said the problem had been resolved as of 3 a.m. eastern time on Friday.

As of 3 a.m. ET the system issue has been resolved. Any delayed flights are resuming and we apologize again for the inconvenience.

— United Airlines (@united) October 14, 2016

It is the third computer glitch to hit United’s owner United Continental Holdings (UAL) in recent months and the latest in a series of problems that have tested the reliance on technology of some of the world’s largest carriers.

On June 2, software needed to dispatch United’s flight plan briefly lost functionality.

In July, the same airline’s flights were disrupted after a computer problem blocked access to reservations records.

The following month, Delta Air Lines (DAL) canceled hundreds of flights and delayed many others after a power outage hit its computer systems.

And in September, a system-wide computer problem at British Airways caused significant delays.

After the two previous incidents, United Continental Holdings said in July it had invested in backup plans.

But multiple recent outages have prompted some experts and passenger groups to question whether the airline industry has invested enough in technological infrastructure, given new profits from baggage and cancellation fees.