title: How to install version of json.net compatible with .net 4.0?
body: <p>To avoid the issue described here:</p>
  
  <p><a href="https://stackoverflow.com/questions/13748055/could-not-load-type-system-runtime-compilerservices-extensionattribute-from-as">Could not load type &#39;System.Runtime.CompilerServices.ExtensionAttribute&#39; from assembly &#39;mscorlib</a></p>
  
  <p>I'm trying to build my project to target .net 4.0 instead of 4.5 (in Visual Studio 2013), but I get the following errors:</p>
  
  <ul>
  <li><p>The type or namespace name 'Newtonsoft' could not be found (are you
  missing a using directive or an assembly reference?)</p>
  
  <p>The primary reference "Newtonsoft.Json" could not be resolved because
  it was built against the ".NETFramework,Version=v4.5" framework. This
  is a higher version than the currently targeted framework ".NETFramework,Version=v4.0".  </p></li>
  </ul>
  
  <p>So I would like to install a version of json.net that is compatible with .net 4.0.  I see that the downloaded NuGet package contains a lib/4.0 directory in addition to lib/4.5, but I can't figure out how to get the package manager to use this instead of the 4.5 version.</p>
  
  <p>How can I get my project solution to buikd using the version of json.net compatible with .net 4.0 instead of the one that only works with .net 4.5?</p>