One of my CSRs tried to run a charge and got the error, “Cannot process an ECC credit card payment method.” Other CSRs have since been able to run other charges, so it seems related to one particular customer or order.
We do not use ECC, and Customer.ECCType is blank for the affected customer.
Turns out that CreditTran.ResponseMsg was “Declined”. I still don’t know why the error message was mangled before it reached the user. There are other recent declines in CreditTran, but I haven’t received any other reports of this issue.