I want to assign one master page dynamically for a pure aspx file, Anybody can tell me, how to do this?
You can override OnPreInit in your default.aspx.cs and set the master page based on some value in your querystring. Something like this:
protected override void OnPreInit(EventArgs e)
{
base.OnPreInit(e);
if (Request.QueryString["Master"] == "Simple")
MasterPageFile = "~/Masterpages/Simple.Master";
}
EDIT: the cause of your error message might be covered by this question.
I Left the ContentPlaceholder to add on it.. Actually , I tried to assign master page without using ContentPlaceHolder.. Now, I realised that, atleast one ContentPlaceholder should be there temporarily, even though we will change the master page dynamically...