Rail firms across the country are warning of problems with pre-paid ticket collection from machines and have advised passengers to bring their collection email or text message with them.
According to the BBC, Greater Anglia, Thameslink, Stansted Express, Southern, Southeastern and Scotrail have all confirmed their advanced ticket service have been affected.
National Rail has advised that passengers can still collect their tickets from staffed ticket offices, with Rail Delivery Group saying the problem is with one supplier of machines.
The issue is not affecting all machines in the country, according to a Rail Delivery Group spokesman.
The fault is only with the collection of pre-paid tickets and passengers can still buy all other ticket types at the machines.
Meanwhile, London Northwestern Railway says it has informed its staff to accept ticket collection emails and text messages as proof of purchase.