XML Parsing Error: no element found

I kept getting the error “XML Parsing Error: no element found ….” and was unable to trace it. To debug, I commented out most of the code on my page markup and just added “Hello World”. All was fine.

Then I started uncommenting out chunk of code step by step. During the process, I found that as soon as I uncommented one of my usercontrol code, it started breaking.

Once I found where to look at, I noticed, I had ScriptManager added to my page as well as my usercontrol. The UserControl was copied over from one of my other project.

I went ahead and changed the <ScriptManager> on the usercontrol to <ScriptManagerProxy> and all started working fine.

Hope this helps.