title: The required anti-forgery cookie is not present
body: <p>I keep seeing the error "The required anti-forgery cookie "__RequestVerificationToken_L3N0dWRlbnQ1" is not present." in my ELMAH logs but I cannot reproduce the error myself.  </p>
  
  <p>My controller action looks like this:</p>
  
  <pre><code>[HttpPost]
  [ValidateAntiForgeryToken]
  public ActionResult SignIn(LoginModel loginModel)
  </code></pre>
  
  <p>and my view looks like:</p>
  
  <pre><code>@using (Html.BeginForm("SignIn", "Home", "", FormMethod.Post, new { @class = "form-inline LoginForm" }))
  {
      @Html.AntiForgeryToken()
      ...
  }
  </code></pre>
  
  <p>The ELMAH log indicates the following form item was posted:</p>
  
  <pre><code>&lt;form&gt;
     &lt;item name="__RequestVerificationToken"&gt;
        &lt;value string="UjQsZ1QB4ryA-e0RleFb7f0ORB9QPbsJrzoXn6D8XiqN9CEGysiVC94Ark4FnAFfx3C2eAG5KhAiVlP8nob8xkCg2k_8oUyLYwDmR39qu8g1"/&gt;
     &lt;/item&gt;
     ...
  &lt;/form&gt;
  </code></pre>
  
  <p>however the only cookie present was the ASP.NET Session cookie</p>
  
  <pre><code>&lt;cookies&gt;
     &lt;item name="ASP.NET_SessionId"&gt;
        &lt;value string="d4rlkdgp1ot2gpcmjtirfym1"/&gt;
     &lt;/item&gt;
  &lt;/cookies&gt;
  </code></pre>
  
  <p>I also noticed that there is a query string value in the post which I did not explicitly set.</p>
  
  <pre><code>&lt;queryString&gt;
     &lt;item name="Length"&gt;
        &lt;value string="0"/&gt;
     &lt;/item&gt;
  &lt;/queryString&gt;
  </code></pre>
  
  <p>Any ideas?</p>