Required String parameter is not present error in Spring MVC

On the server side you expect your request parameters as query strings but on client side you send a json object. To bind a json you will need to create a single class holding all your parameters and use the @RequestBody annotation instead of @RequestParam.

@RequestMapping(value = "events/add", method = RequestMethod.POST)
public void addEvent(@RequestBody CommandBean commandBean){
    //some code
}

Here is a more detailed explanation.