Passengers at at least three UK major airports on Friday faced disruption and delays caused by electronic failures affecting the passport gates.
London Heathrow, Manchester and Edinburgh all reported issues to the e-gates that allow passengers to quickly pass through border controls.
The problem forced thousands of people to wait in long queues in order to get their documents checked by immigration officers.
Flight disembarkments were delayed too.
Around two hours after communicating the issue, Heathrow Airport announced the problem had been solved.
"Our teams remain on hand and are working with Border Force to monitor the situation, and to get passengers on their way as quickly as possible", the airport authorities said.
A UK Home office spokesperson also said the problem was "identified and fixed" nationwide.