I tried to implement AJAX on my website by using AJAX extension on visual studio .NET. I tried to drag update panel to my page and I’ve put my button event handler to the trigger collection in update panel. I was expecting when i click that particular button then it will not refresh or load up the page, but in fact it reloads the page which showing me that the AJAX panel does not work, and my firebug detects that there are errors related with sys is undefined.

This happens because I haven’t AJAX config on my web.config. The config is related with HTTP handler, you can try to put this in your web.config. Please make sure it should be inside “”