If user submits an order online using Reference Checkout on a Test or SandBox account and it throws an Exception when submitting order, follow steps below:
1. Login to the Test or SandBox account
2. Navigate to Setup> Site Builder> Setup Website> Shopping tab
3. Set the Require Authorization for Credit Card Transactions = F
Before, when the Require Authorization for Credit Card Transactions is checked, the error will throw a different error such as We were unable to authorize this purchase with the credit card information given. Please go back and check the accuracy of the information provided.