在我的情况下，我在启动项目和使用同名服务的项目中都添加了服务。它工作…

我也有同样的问题。事实证明，对于web REFERENCE，你必须将URL作为构造函数的第一个参数:

new WebService.WebServiceSoapClient("http://myservice.com/moo.aspx");

对于一个新样式的web SERVICE REFERENCE，你必须在配置中提供一个引用端点条目的名称:

new WebService.WebServiceSoapClient("WebServiceEndpoint");

在Web中使用相应的条目。config或App.config:

<client>
      <endpoint address="http://myservice.com/moo.aspx"
        binding="basicHttpBinding" 
        bindingConfiguration="WebService"
        contract="WebService.WebServiceSoap"
        name="WebServiceEndpoint" />
    </client>
  </system.serviceModel>

很难消除“它在旧的程序中工作”的狭隘观点……

There seem to be several ways to create/fix this issue. For me, the CRM product I am using was written in native code and is able to call my .NET dll, but I run into the configuration information needing to be at/above the main application. For me, the CRM application isn't .NET, so I ended up having to put it in my machine.config file (not where I want it). In addition, since my company uses Websense I had a hard time even adding the Service Reference due to a 407 Proxy Authentication Required issue, that to required a modification to the machine.cong.

代理解决方案:

为了让WCF服务引用工作，我必须从我的DLL的app.config复制信息到主应用程序配置(但对我来说是machine.config)。我还必须将端点信息复制到同一个文件中。一旦我这么做了，它就开始为我工作了。

我曾经遇到过这个问题。这是因为我还在开发使用WCF服务的接口。我配置测试应用程序和继续开发。然后在开发中，我改变了一些服务的名称空间。所以我再次检查了“系统”。serviceModel ->客户端->端点->合同”。配置匹配WCF类。那么问题就解决了。

我遇到了同样的问题，只有当主机应用程序和使用该端点的dll具有相同的服务引用名称时，才解决了这个问题。

对使用服务的非库应用程序进行单元测试可能会导致此问题。

The information that others have entered addresses the root cause of this. If you are trying to write automated test cases and the unit you are testing will actually invoke the service interface, you need to add the service reference to the test project. This is a flavor of the application using library type of error. I did not immediately realize this though because my code that consumes the interface is not in a library. However, when the test actually runs it will be running from the test assembly, not the assembly under test.

向单元测试项目添加服务引用解决了我的问题。