Demand for the new millennial railcard has crashed the website on the first day of nationwide sales.
The one-year railcard for 26 to 30-year-olds will cost £30 and offer a third off most fares in England, Wales and Scotland.
It first went on sale nationwide at about 07:30 GMT but “exceptional demand” has caused the website to fail.
Only 10,000 railcards are being released during the trial, and it is only available to buy online.
“We’re sorry to those who have been unable to buy a trial 26-30 Railcard this morning. This is due to the exceptionally high volume of traffic on the 26-30 Railcard website,” said a spokeswoman for the Rail Delivery Group, which represents the train companies and Network Rail.
“We are increasing the capacity on the website to better manage the high level of traffic. Railcards are still available to purchase and people should keep checking @_Railcards Twitter and Facebook pages for updates.”
The limited number of cards – enough for one in 500 of the eligible population – went on sale on Tuesday following a trial across the Greater Anglia network when another 10,000 railcards were sold.
Applications can only be made on the 26-30 railcard website, and holders need to download an app before they can use the card. However, the site states that the service is unavailable when visitors press the “buy” button.
The card does not cover all travel. The discount for some during the morning commute is limited as a minimum fare of £12 applies to all journeys made before 10am, Monday to Friday.
The Rail Delivery Group said discounts were not given on season tickets, but a weekly or monthly season ticket could still be the cheapest option for those in this age bracket who commuted frequently by train.