Ryanair passengers were left frustrated on Thursday afternoon after the airline's website and app went offline once again.
The 'scheduled maintenance' during a peak time was the second occasion in less than 24 hours that passengers were unable to access its services online.
A customer service representative said the Irish company was "experiencing some technical difficulties" at 3pm.
A subsequent update from Ryanair on Twitter read: "Our website/app is undergoing scheduled maintenance from 15:00 until 15:45."
However, it appears many passengers were unaware that the app and website would not be operational and voiced their concern online.
Many were having difficulty checking in, as well as booking flights and accessing their boarding passes.
People already at airports also expressed their worry as they needed to check-in before an upcoming flight.
One person said: "@Ryanair I can't access my boarding pass. The app has logged me out. Your website says you're down for maintenance. What am I meant to do? I'll be boarding my flight in an hour!!"
A second said: "@Ryanair Are you serious? Yesterday maintenance of the website and impossibility to do the check-in. Now both the website and app still down. What am I supposed to do???"
A third added: "I'm at Manchester Airport and I can't board my flight cos I can't access my boarding pass!"
Another said: "Cmon guys I’m in the airport and cannot check-in. You got this, but fast please."
Someone else commented: "@Ryanair how can we check in???? We have a flight in 3 hours!!!! Urgent please."
In a new update from Ryanair at 4.30pm, a spokesperson said: "Our website/app is currently unavailable due to ongoing maintenance.
"Any customers who are due to depart in the next 2 hrs & who are experiencing issues accessing their boarding passes, should proceed to the ticket desk. We apologise for this inconvenience."
It comes after the app and website were out of action for hours on Wednesday night as scheduled maintenance was carried out.
Ryanair said: "Due to scheduled maintenance, the Ryanair website / app will be temporarily unavailable from 19:00hr GMT on Wednesday, 23rd March for a number of hours.
"Customers who are due to fly must check-in online before Wednesday, 23rd March 19:00hr GMT.
"Customers who wish to make bookings, flight changes / name changes, online check-in and all other aspects regarding a flight booking will be unable to do so during this period of maintenance."
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