How to resolve "__doPostBack is not defined" error
It just happened to me... I put my script in an file and declare it in the header like this :
<script src="js/masterpage.js" type="text/javascript" />
When I launch the page, I get a javascript error
__doPostBack is not defined and none of my javascript functions is executed.
It seems that some tags need a closing tag and don't understand "/>", it's the case of the script tag but not of link, used to call my css style sheets for example. Using this code works :
<script src="js/masterpage.js" type="text/javascript"></script>