title: Could not load file or assembly 'System.Security.Principal.Windows'
body: <p>Solution has compiled successfully, but after I added an existing class file to the project, this error appeared:</p>
  
  <blockquote>
    <p>The specified task executable "csc.exe" could not be run. Could not
    load file or assembly 'System.Security.Principal.Windows,
    Version=4.0.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or
    one of its dependencies. The system cannot find the file
    specified.    MvcApplicationRegister</p>
  </blockquote>
  
  <p>I installed <code>System.Security.Principal.Windows</code> package By NuGet, but error still appears.      </p>