SharePoint 2010 - Custom Sign In Page: 401 Unauthorized

Recently when developing a custom sign in page I was encountering an “401 Unauthorized” error.  

The cause of this error was that my application page was inherited from LayoutsPageBase.  

In order to fix this I changed the application page to inherit from System.Web.UI.Page.

Throws 401 Unauthorized

public partial class Login : LayoutsPageBase

Resolution

public partial class Login : System.Web.UI.Page