Drop Down selectedindexchanged not firing in IE10

The issue is ASP.NET browser definitions do not recognize IE10 so it defaults to a down-level definition, which has certain inconveniences, like that it does not support features like JavaScript.

An alternative to the machine wide hotfix(s) or site level App_Browser solutions is to simply add Page.ClientTarget = "uplevel" to the Page_Init method in the code behind:-

Solution:-

private void Page_Init(object sender, EventArgs e)

{

Page.ClientTarget = "uplevel";   

}