title: ASP.NET Debugger is not stopping at server-side breakpoint when CallBack is called
body: <p>I am debugging code on a webforms site and the javascript runs a callback which then goes to the code behind but skips my breakpoints since the server-side code is running on a separate thread. Any tips on debugging this?</p>
  
  <p>The JS:</p>
  
  <pre><code>testCallBack.Callback(param1);
  </code></pre>
  
  <p>Code Behind:</p>
  
  <pre><code>Protected Sub testCallBack_Callback(ByVal sender As Object, ByVal e As CallBackEventArgs) Handles testCallBack.Callback
         'My break point is in this function
         functionThatisErroring()
  End Sub
  </code></pre>
  
  <p>I put a breakpoint in the function and the debugger isn't stopping. Instead it just skips to the on CallBack error function in JS which displays an alert error message. </p>
  
  <pre><code>&lt;ClientEvents&gt;
        &lt;CallbackError EventHandler="testCallBack_Error" /&gt;
  &lt;/ClientEvents&gt;
  </code></pre>
  
  <p>The server-side error is getting sent to my email but is very general so can't figure it out unless I can step through the function.</p>