United Airlines resolved the system disruption that delayed over 1,000 flights, but residual delays are expected and the cause is unknown.

United Airlines suffered a major "technology disruption" on Wednesday night, the carrier has told Newsweek via email, leading to widespread travel chaos in the United States and beyond, and it later warned of "residual delays" even though the underlying issue had been resolved.

United Airlines resumed operations on Wednesday night after a technology issue grounded all mainline flights, leading to over 1,000 delays.