Ryanair will close its online reservation and registration systems 12 hours later this week.
Conclusion – from 17:00 to Wednesday to Friday to Friday – enables the airline to upgrade its computer systems.
Ryanair said that travelers traveling these days must check and print entry tickets before or after the shutdown.
Dublin's company said it sent emails and text messages to customers flying on Wednesday or Thursday and told them to check on the Internet on Tuesday.
Ryanair's policy is to charge an additional 55 pounds to passengers if they need to check in at the airport. It is unclear whether this will let those who forget to report before the system leaves the system.
The online application is open only 48 hours to two hours before the year for travelers who have not paid to select a seat.
New reservations, changes in flights or changing passenger data will also be affected, as well as the ability of passengers to review existing reservations.
The closure includes an airport website and a telephone application.
Ryanair Communications Manager Robin Kiely said that the suspension of its website and mobile applications is part of the "continued digital development" of the airline.
He added: "We sincerely apologize for any inconvenience caused by this upgrade, which will further improve Ryanair.com, the largest European travel website".
The news comes as Ryanair concludes its base unit in Eindhoven, the Netherlands, which denounces 16 workers in the cabin as it continues the long conflict between airline chiefs and staff.
According to the national NOS television, 16 cabin workers who were working in the company for less than a year and having had less protection at work were dismissed.
Of the 60 other cabin crew members, approximately half of them agreed to Ryanair's offer to move to another base, said the NOS.
Judges in the Dutch court said that the company appears to be closed base in retaliation for strikes across Europe recently joined by Dutch pilots.
Ryanair will continue to fly through Eindhoven, but flights will not spring up, said the airline.
She also announced plans to close down two bases in Germany.