Possible Ajax Error Code and Reasons

400 (Bad Request)

• In jQuery, no JSON.stringify() is used to parse JavaScript object to JSON object

• Use $.ajax() but doesn't include type: "GET/POST/etc" in AJAX body

406 (Not Acceptable Response)

• Check your authority setting. One of my Spring MVC project has requirement: user group 1 can only access sub-URL of /test/user1. So if I make a URL mapping to /test/, AJAX call will fail and give me a 406 error

404 (Not Found Errors)

Very common error. Can have different reasons:

• dataType, contentType, mimeType may not corresponding to correct type.

• In Spring MVC, no @ResponseBody or @RequestBody is added in controller. For example: public @ResponseBody String test(@RequestBody final String id) is good. But public String test(@RequestBody final String id) can generate a 404 error in client side.

No response (Back-end finsih processing but front-end give no response)

• Check your jQuery version and check if you are using $.ajax({done: function(data../){}, fail: function(jqXHR...){}});. If so, try to check your jQuery to later version, or replace with $.ajax({success: function(data...){}, error: function(jqXHR...) })