Roughly 3,500 flights were affected.
A computer glitch caused widespread delays and frustration at airports around the world for United passengers on Thursday.
Originally the airline said that 63 flights were affected, but later retracted that statement, saying only that a “small number” of flights had been delayed “given the overnight timing.”
"Earlier tonight we experienced an issue with our weight reporting system, which caused system wide flight delays," United said in a statement.
The delays caused long waits at airports around the world, but lines were particularly bad on the West Coast. Agents at Los Angeles International Airport were forced to issue paper tickets and check passengers in on a sheet of paper.
Other flights with passengers were forced to wait on the tarmac for an open gate. The airline’s website and app also were down during this time. Passengers from San Francisco, Costa Rica and London posted pictures on social media with their frustration.
The issue was resolved at 3 a.m. ET Friday morning.
This is the third outage United has experienced since June. The largest was in July when the airline’s computer system experienced a power outage that affected about 3,500 flights. After the outage, United said that it was investing in better backup.
This piece originally appeared on TravelAndLeisure.com.