我遇到了同样的问题，我要解决的问题是转到系统/配置/Magento Core API"并将"WS-I Compliance"值设置为否".
我正在使用使用Magento V2 API的WebService，我不记得是否使用此值为"Yes"来生成Web参考.我正在使用VS 2010使用WS C#.

I had the same issue, and which I did to fix it was to go to System/Configuration/Magento Core API and set the value WS-I Compliance as 'No'.
I'm working with a WebService which consumes the Magento V2 API, I don't recall if I generate the web reference using this value as 'Yes'; I'm working with a WS C# using VS 2010.