ErraiAutoServlet will now become the default servlet to configure.   This servlet contains a mechanism for automatically detecting which application server you are running on and automatically choosing the most appropriate implementation.

Remove the Guice-Servlet listeners from your web.xml and replace it with the following declaration:

    <servlet>
        <servlet-name>ErraiAutoServlet</servlet-name>
        <servlet-class>org.jboss.errai.bus.server.servlet.ErraiAutoServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet

    <servlet-mapping>
        <servlet-name>ErraiAutoServlet</servlet-name>
        <url-pattern>*.erraiBus</url-pattern>
    </servlet-mapping>

... this is all you need.