title: To check if session is available or not
body: <p>I tried some code in <code>Application_Error</code> like this</p>
  
  <pre><code>Session["mysession"] = "Some message";
  </code></pre>
  
  <p>but the problem is sometimes session is not available in <code>Application_Error</code>. So I want to check whether session is available or not.</p>