title: SignalR asks for authentication credentials with 401
body: <p>I have a .Net 4.5 website with MVC, Web API, and SignalR, and using Windows authentication.  Everything runs great until I add the hubs to my HTML with:</p>
  
  <pre><code>@Scripts.Render("~/signalr/hubs")
  </code></pre>
  
  <p>With this line in place, about 1/3 of the time when I hit F5 to refresh the page, before the page loads I get a username/password prompt.  This sometimes affects just the hub, other times it affects some MVC views, and sometimes it affects the entire page.  I have this in my <code>Startup.cs</code>:</p>
  
  <pre><code>public class Startup
  {
      public void Configuration(IAppBuilder app)
      {
          app.SetDefaultSignInAsAuthenticationType(NtlmAuthenticationDefaults.AuthenticationType);
          app.UseNtlmAuthentication();
          app.MapSignalR(new HubConfiguration()
          {
              EnableDetailedErrors = true,
              EnableJSONP = true
          });
      }
  }
  </code></pre>
  
  <p>In <code>web.config</code>:</p>
  
  <pre><code>&lt;authentication mode="Windows" /&gt;
  &lt;authorization&gt;
      &lt;deny users="?" /&gt;
  &lt;/authorization&gt;
  </code></pre>
  
  <p>I notice in Fiddler that requesting hubs.js has a <code>Authorization: Negotiate ...</code> header.  Immediately after is a second request, also for hub.js, with <code>Authorization: Negotiate ...</code>, but the hash is different.</p>
  
  <p>Does anyone have any idea why this is happening and how to solve it?  Additional diagnostic information can be provided upon request.  Note that I'm not actually connecting to the SignalR hub.  All I'm doing at this point is loading the hubs JS.</p>
  
  <ul>
  <li>SignalR: 2.2.0</li>
  <li>Microsoft.Owin.Host.SystemWeb: 3.0.1</li>
  <li>Pysco68.Owin.Authentication.Ntlm: 1.0.2</li>
  </ul>
  
  <p>This appears to only happen with Chrome.  IE has thus far worked flawlessly.</p>
  
  <p><strong>Edit: The issue goes away completely when I close Fiddler.</strong>  So now the question becomes: why does the combination of MVC, SignalR, and Fiddler break Ntlm?  If I remove the hub, it works.  If I close Fiddler, it works.  What?</p>