beta 2 error: no support to generic eventargs?

Hi, I got compiling error: The type 'string' cannot be used as type parameter 'TEventArgs' in the generic type or method 'System.EventHandler<TEventArgs>'. There is no implicit reference conversion from 'string' to 'System.EventArgs'.
The code was working in beta 1 but not working in beta 2. Following is the test code:
    public partial class Page : UserControl
    {
        public Page()
        {
            InitializeComponent();

            testhandler(handler);
           
        }

        void handler(object sender, string str)
        {
 &nb ...