title: TFS 2017 custom call TeamFoundationApplication.Log
body: <p>I moved my project from TFS 2010 in TFS 2017. But now I am getting an error: <a href="https://msdn.microsoft.com/library/gg234423(v=vs.100).aspx" rel="nofollow noreferrer">TeamFoundationApplication.Log</a>
  <pre><code>TeamFoundationApplication.Log(String.Format("ChangeWIState: {0}; state: {1}", wi.Id, state), 1, EventLogEntryType.Information);
  </pre></code></p>
  
  <blockquote>
    <p>Error1:   CS0012  The type 'HttpApplication' is defined in an assembly that
    is not referenced. You must add a reference to assembly 'System.Web,
    Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.</p>
    
    <p>Error2:    CS0117  'TeamFoundationApplication' does not contain a >definition for 'Log'What it the problem?</p>
  </blockquote>