If, after October 1, you turn up at the airport without having checked in online, you also risk a sizeable charge - though an airline spokesman told me Ryanair will 'do its best to help those who have tried to print off their boarding cards but have had problems'.
Well they certainly haven't done up till now. I fly regularly EMA-SFX and while the Berlin staff will always print my boarding pass if I tell them the website wasn't working, the UK staff have "no option" but to charge you - first £8, then shortly afterwards, £10 - to do it. They just can't get round it, followed by something about "Servisair".
The second time was following a last minute flight change which left no time to get to a printer except through an internet cafe the morning of the flight. However despite what they claim the Print Boarding Pass option isn't available once the 4 hours deadline for amending flight details has passed. It very easily could be - only a matter of copying and pasting a link onto a web page - but they choose not to provide it and thus rake in ... er ... must be
£12 by now? - every time someone needs to do this.