When I execute the getMerchantDetailsRequest request in c# with the latest nuget package (AuthorizeNet version 2.0.1) it always fails with this error.
"There is an error in XML document (1, 40)."
I copied the code from your API documentation: https://developer.authorize.net/api/reference/#transaction-reporting-get-merchant-details
It has worked all the time until today.
This issue happens on every sandbox account regardless of ApiLoginID/ApiTransactionKey or OAuth2.0 authentication.
However, the Rest API works.
I found that the request returns an enum value "GooglePay" which does NOT exist as a valid paymentMethodsTypeEnum. This is causing the "getMerchantDetailsResponse" object to fail to parse, causing the request to fail.
It looks like fix is just updating a source from here: https://github.com/AuthorizeNet/sdk-dotnet/blob/master/Authorize.NET/Api/Contracts/V1/AnetApiSchema....
to add GooglePay into the paymentMethodsTypeEnum.