Europe's biggest airport London Heathrow said on Thursday that an issue preventing bags from being checked in at terminals 3 and 5 had been resolved and apologised to those passengers who had to fly without luggage on early morning flights.
Heathrow, which suffered massive disruption last month when a power surge knocked out British Airways' IT system, said bag drop desks were now operating normally. Terminals 2 and 4 had not been affected by the issue.
"We recommend that passengers who have already departed on flights this morning without their baggage contact their airline for further updates," it said on Twitter.
"We are sorry to passengers affected by this issue."
Heathrow had earlier said that some passengers would have to travel without their bags and urged passengers to pack essential items in their hand luggage.
Travellers had used social media to vent their anger, with one user Tariq Panja showing pictures of luggage piled up with the caption "another day another Heathrow baggage fiasco".
"Baggage failure at @HeathrowAirport this morning. Bags won't be making it onto flights, absolute shambles," said Ryan Wooldridge on Twitter.