Hi Robert,
There is no param changes for AuthNet provider, It's working fine. Also returns right params with message "transaction successful".
The error is thrown when the generateOrderConfirmation() method of PaymentControlBase is called from AuthorizeNetPayment.ascx.cs page. The error is thrown from following line.
//Order email header
String _Message = Services.Localization.Localization.GetString("OrderEmailHeader", this.LocalResourceFile);
textLine = String.format(_Message, PortalSettings.PortalName, tabInfo.TabName, storeEmail);
emailText.Append(textLine + "\r\n\r\n");
There is not such a key as OrderContents in resource file so _Message become null. Now in very next line when null is passed to String.formate it throws error. "Value cannot be null. Parameter name: format"
Not only the OrderContents but all the following key are not found from resouce file. Event have tried by adding all these keys to AuthorizeNetPayment.ascx.resx but still the error not resolveed.
OrderBillingAddress
OrderCannotBeProcessed
OrderContents
OrderEmailHeader
OrderItems
OrderNumber
OrderShipping
OrderShippingAddress
OrderSubject
OrderSubjectToAdmin
OrderSubTotal
OrderTax
OrderTermsOfUse
OrderThanks
OrderTotal
Thanks,
Mahesh