title: ASP.net web.config doesn't catch all 404's
body: <p>In my web.config I have:</p>
  
  <pre><code>    &lt;customErrors mode="On" defaultRedirect="~/Error.aspx" redirectMode="ResponseRewrite"&gt;
          &lt;error statusCode="500" redirect="~/Error.aspx" /&gt;
          &lt;error statusCode="404" redirect="~/404.aspx" /&gt;
      &lt;/customErrors&gt;
  </code></pre>
  
  <p>Yet with these URL's, only the 2nd one with file extension defined works, the other one returns the blue screen 404 "Server Error in Application".</p>
  
  <pre><code>http://127.0.0.1/scirranew/invalidpath
  
  http://127.0.0.1/scirranew/invalidpath.aspx
  </code></pre>
  
  <p>Any ideas?  I'm on ASP.net 4, IIS 7.5.</p>