I am receiving this error when a customer is trying a transaction. What causes it?
closed as off topic by Polynomial, makerofthings7, Iszi, Rory Alsop♦ Nov 19 '12 at 13:55
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It simply means that the magnetic stripe on the card is unreadable, or the reader itself is broken or gummed up. There are 2 tracks on the magnetic stripe on a credit card, track 2 in this case is damaged or perhaps simply covered with some sort of dirt or dust. Try cleaning the card and/or the reader.
From a security perspective it could be that this credit card is counterfeit, that it was done badly, however there's no way you can really tell. More likely it's just a bad card.