C# Get Windows User Display Name Error with UserPrincipal

Question

I've been trying to get the display name of a user for an app I'm building. I worked on the accountmanagement.dll in my project and I'm using this code to grab the name:

string userFullName = UserPrincipal.Current.DisplayName;

The following error messages comes up in debug:

Unable to cast object of type

'System.DirectoryServices.AccountManagement.GroupPrincipal'

I'm obviously missing something but not sure about the next step. Any help would be appreciated.

Answer 1

This is a way to get the windows logged in user name when developing a web app:

string userFullName = Page.User.Identity.Name;

and web.config:

<system.web>
    <authentication mode="Windows"></authentication>
</system.web>