Ryanair has said that its website and mobile app will close for 12 hours for a systems upgrade.
The upgrade will take place from 5pm (Irish time) on Wednesday, November 7, until around 5am (Irish time) on Thursday, November 8.
It means its online check-in service will not be available during this period.
Ryanair said it has contacted all customers booked to travel on those dates by email and SMS text to advise them to check-in online for their flight tomorrow, before the web closure takes place.
New bookings or changes to existing flights will not be possible during this closure. Ryanair apologises for any inconvenience caused by this systems upgrade.
However, in a separate route announcement today by the budget airline, they also said that customers will be able to book return flights with €20 off as part of their ‘Winter Winners’ sale until midnight on Wednesday, November 7.
When asked for clarification they said the sale will now end at 5pm on Wednesday.
Ryanair’s Robin Kiely said: “As part of our continued digital development, a web closure and system upgrade will take place for 12 hours, from 17:00hrs (UK time) on Wednesday 7th November, until 05:00hrs (UK time) on Thursday 8th November, during which time our online check-in service will not be available.
"Flight bookings and changes will also be unavailable during this period. Customers travelling on Wednesday or Thursday should check-in for their flight on Tuesday 6th November.
"We sincerely apologise for any inconvenience caused by this upgrade, which will further improve Ryanair.com, Europe’s largest travel website.”
The airline announced the new route from Dublin to Bodrum, Turkey, as part of its Summer 2019 schedule.
The twice-weekly service will start in May 2019.
Mr Kiely said: "This new route is on sale now on the Ryanair.com website and to celebrate we are also offering up to €20 off return flights for travel between now and February 2019 as part of our ‘Winter Winners’ sale.
"These amazing low fares are available for booking until midnight Wednesday (7 Nov).”
However, an airline spokesperson later said: "With the website closure, the sale will now end at 5pm on Wednesday."