ScotRail is among a number of rail firms reporting problems with pre-paid ticket collection from machines across the country.
Scotland's train operator confirmed the issue has been affecting passengers on Tuesday.
ScotRail said a significant number of its ticket machines were affected but added that customers could still travel if they showed their proof of purchase.
National Rail said people could collect their tickets from ticket offices.
Passengers using the ticket collection machines are reporting that the button to collect pre-paid tickets is greyed out.
A spokesman from the Rail Delivery Group, which represents train operators, said the problem was with one supplier of the machines.
He said: "Passengers with some train companies have this morning been experiencing problems collecting tickets from machines.
"We're sorry for the inconvenience caused and are working with the relevant supplier to fix the problem as soon as possible.
"People affected should speak to their train company or visit the ticket office."
The issue is only affecting collection of pre-paid tickets. All other ticket types can be bought from the machines.
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