I have been fighting with for a week now.
I have patched the Authorize.net files as stated by Magento. I also purchased 2 different Authorize.net CIM extensions but neither works, I get the following error with both.
I try checkout as a guest, I get the error "No such entity with %fieldName = %fieldValue" and then it says "An ID is needed. Set the ID and try again."
So, now I have removed both extensions and reverting back to built in Authorize.net extension.
Now it just says "A server error has prevented your order from being processed"
