This error indicates that you did not enter your credit card number correctly. Please return to the payment screen, make sure that you're entering the 16-digit number on the front or back of your card with no dashes or spaces, and attempt payment again. For AmEx this is a 15-digit number. If the error persists, use your browser's Back button until you are back in the form, and re-initiate the payment attempt from there.
Payment Error: Invalid Card Number (or) Card Number Error
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