How to solve 404 caused by Severe: PWC6117: File "null" not found in Controller?

Question

I have two login pages: AM and Customer login page. When the AM Login successfully it redirects to the chat page with the map /am/chatPage and with the customer it redirects to /customer/chatPage. My problem is it doesn't load the JSP file.

Here is the error in glassfish:

Info:   Show AM CHATPAGE--------------------
Severe:   PWC6117: File "null" not found

Note: The login process is handled by Spring Web Security in my WebSecurityConfig.java

In my Login Controller I have @RequestMapping() for AM Chat page:

@RequestMapping(value = "/am/chatPage", method = RequestMethod.GET)
    public String chatpage(Model model)
    {
        System.out.println("Show AM CHATPAGE--------------------");
        model.addAttribute("name","Sample name");
        model.addAttribute("twitter","@sample");
        return "amChatPage";
    }

and Customer Chat Page:

@RequestMapping(value = "/customer/chatPage", method = RequestMethod.GET)
    public String showCustChat(Model model)
    {
        System.out.println("SHOW CUSTOMER CHAT----------------------");
        return "customerChatPage";
    }

Below is my SpringWebAppInitializer

    @Override
    public void onStartup(ServletContext sc) throws ServletException
    {
        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
        context.register(ApplicationContextConfig.class);
        
        ServletRegistration.Dynamic dispatcher = sc.addServlet("dispatcher", new DispatcherServlet(context));
        dispatcher.setLoadOnStartup(1);
        dispatcher.addMapping("/");
    }

Things that I've done so far:

• I tried the solution in PWC6117: File “null” not found using ModelAndView but still doesn't load.
• Added dispatcher.addMapping("/am/"); or dispatcher.addMapping("/am/**"); in SpringWebAppInitializer.

Assumptions:

I have a controller for map /welcomepage and it works fine and shows the jsp. I also tried loading the amChatPage.jsp and customerChatPage.jsp in this controller and it works fine. I think this error appears with this map pattern /am/** or /customer/**. Can someone help me fix this problem?