The “major incident” was caused by technical problem with its cloud-based reservation and operational systems.
“As we are currently unable to communicate directly with customers, we are asking customers booked to travel on those flights not to come to Dublin Airport,” Aer Lingus said in a statement.
Affected customers will be able to change their travel plans free of charge, the airport said.
Aer Lingus said this can be done through their call centre or social media channels.
“We will advise customers when IT systems are restored and this change option is fully available to our customers.
“Our sincerest apologies to those affected by today’s technical issues.”
The flight cancellations will cause huge disruption for thousands of passengers.