title: Value cannot be null. Parameter name URL on ASP.net form submit
body: <p>I have a ASP.net webform with few controls and when I hit the submit button I am getting the following error</p>
  
  <p>sys.webforms.pagerequestmanagerservererrorexception: Value cannot be null. Parameter name:url</p>
  
  <p>On submit of the button I am just inserting values into the database.</p>
  
  <p>How do I fix this issue?</p>
  
  <p>When I try to put a breakpoint on page load it says No symbols have been loaded for this document.</p>
  
  <p>HTML for the submit button is shown below</p>
  
  <pre><code>&lt;input type="submit" name="ctl00$ContentPlaceHolder1$btnSubmit" value="Submit" onclick="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions(&amp;quot;ctl00$ContentPlaceHolder1$btnSubmit&amp;quot;, &amp;quot;&amp;quot;, true, &amp;quot;&amp;quot;, &amp;quot;&amp;quot;, false, false))" id="ctl00_ContentPlaceHolder1_btnSubmit" /&gt;
  </code></pre>
  
  <p>Please help</p>