Over the last decade our Miva clients have complained that their customers got this message when they tried to place an order in their store:
Error: “Unable to authorize payment: MD5 Hash mismatch. Please contact the store administrator if you continue to experience this problem.”
Urgency Level: HIGH
Cause: if a store owner changes their MD5 Hash Code in their Authorize.net admin area, and forgets to change it in their Miva store, this causes a mis-match. We have also been told that the way that the payment gateway module in Miva doesn’t always talk to Authorize.net consistanty, which can also cause this issue.
Fix: this one is easy. Merely take out the code from the backend of Miva, and the problem will stop.