Web Api: System.Net.Http version 2.0.0.0 not found

问题

When I install the NuGet package for WebApi, it gives me version 1.0.0.0 of System.Net.Http, yet it references version 2.

I cannot seem to find version 2 for the life of me. When I download .net 4.5 I get System.Net.Http version 4.0.315.x, but I cannot use that because the Web Api assemblies refer to version 2.0.0.0.

Anyone know where I can find this version 2.0.0.0? I've tried the NuGet package manager, mvc4, .net 4.5, and nothing is giving me version 2.

Thanks in advance.

回答1:

Add the below configuration inside your Web.config file under <system.web> node (assuming your app runs on .NET 4.5, targetFramework attribute is set to 4.5):

<compilation targetFramework="4.5">
  <assemblies>
    <add assembly="System.Net.Http, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
  </assemblies>
</compilation>

Also add the below one at the root level under <configuration> node:

<runtime>
  <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
    <dependentAssembly>
      <assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" />
      <bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
    </dependentAssembly>
  </assemblyBinding>
</runtime>

This should solve your problem.

来源：https://stackoverflow.com/questions/11941447/web-api-system-net-http-version-2-0-0-0-not-found