The problem left an unknown number of passengers stranded or delayed while waiting to board international flights.
The carrier said it was re-booking some customers onto alternative flights and offering hotels to those who are “unable to continue their journeys.”
The airline has been hit by a series of technical snafus in recent years. British Airways was forced to cancel over 100 flights in August when its computer systems crashed.
In 2017, it canceled flights from London’s Heathrow and Gatwick airports after “a major IT system failure” caused severe disruption to its global operations, stranding 75,000 customers.
-— Jaide Garcia contributed reporting