Exception thrown when loading some JS functions

[Hamzah Khamash]

Dears ,
I am working on a big size Spring MVC project , The application is loading a set of JS files ,
some of these JS files throw 500 error in the browser , when i type the url that is related to the JS files that are failing on the browser i got this error :

java.lang.ClassCastException: org.springframework.web.servlet.ModelAndView cannot be cast to java.lang.String
	$Proxy117.toString(Unknown Source)
	java.lang.String.valueOf(String.java:2827)
	java.lang.StringBuilder.append(StringBuilder.java:115)
	org.springframework.web.servlet.HandlerExecutionChain.toString(HandlerExecutionChain.java:122)
	java.lang.String.valueOf(String.java:2827)
	java.lang.StringBuilder.append(StringBuilder.java:115)
	org.springframework.web.servlet.handler.AbstractUrlHandlerMapping.getHandlerInternal(AbstractUrlHandlerMapping.java:124)
	org.springframework.web.servlet.handler.AbstractHandlerMapping.getHandler(AbstractHandlerMapping.java:288)
	org.springframework.web.servlet.DispatcherServlet.getHandler(DispatcherServlet.java:1040)
	org.springframework.web.servlet.DispatcherServlet.getHandler(DispatcherServlet.java:1025)
	org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:863)
	org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827)
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
	org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

Any suggestions about the root cause of this problem

[Praful Thakare]

First line has the clue java.lang.ClassCastException: org.springframework.web.servlet.ModelAndView cannot be cast to java.lang.String looks like the action methods causing this error are returning ModelAndView object where as String is expected. check the return type and return statements of these methods.

[Jayesh A Lalwani]

Are you going through the controller to get to JS files?