Forms authentication with custom principal and IIS 7/IIS 6 difference

Hello all,

I came across a difference in the behaviour of ASP.NET when using forms authentication within an application. I would like to know where this difference comes from, maybe somebody can provide some information about it.

This is the situation:

I have a website with a CMS application in it. When I add an application to the website with IIS 7 the following method to get a reference to the user works: 1 void Application_OnPostAuthenticateRequest(object sender, EventArgs e) {
2 // Get a reference to the current User.
3 IPrincipal usr = HttpContext.Current.User;
4
5 // If we are dealing with an authenticated forms authentication request.
6 if (usr.Identity.IsAuthent ...