Rail ticket machines across the UK fell out of service this morning preventing commuters from using them to pay fares.
On-screen messages said they had "no online connectivity", making them unable to send payment card details. The issue began at about 06:00 BST.
A spokesman for the Rail Delivery Group (RDG) told the BBC the issue had been resolved shortly before 09:00 BST.
He added that the fault appeared to have been with the software and systems provided by Scheidt & Bachmann.
A spokeswoman for the German firm was unable to provide additional information.
RDG later issued a statement saying: "We're sorry that some customers were inconvenienced by a technical fault which affected one supplier's system, which meant that some train companies' ticket machines, not all, couldn't authorise card payments."
Southern Rail, Greater Anglia, Great Northern and ScotRail were among those affected to have apologised via Twitter after customer complaints.
Manchester's Metrolink confirmed that ticket machines for its tram network had also been disrupted as a consequence.
"The problem is now fixed and all our machines are able to accept credit cards," added a spokesman for Thameslink.
"Anyone who was unable to buy a ticket as a result of the problem will not be penalised."
However, notices on others' ticket machines suggested they were still having a problem at lunchtime.
Customers were still able to buy tickets online via the web and apps while the faults were ongoing.