Tomcat Show HTTP Status 400 Error Page During Validation - spring

Question

I'm learning to make Bean Validation works in Spring MVC with Thymeleaf as default view. Every valid data can be saved properly. But when I tried an invalid data passed, Tomcat just showed HTTP Status 400 Error page. In Tomcat console showed something like validation but just became logging text in Tomcat console. Here is the controller that saves data (item).
#Controller
#RequestMapping("/item")
#SessionAttributes("item")
public class ItemController {
#Autowired
private ItemService itemService;
#Autowired
private ColorService colorService;
#ModelAttribute("allColors")
public List<Color> populateColors() {
return colorService.findAll();
}
#ModelAttribute("allItems")
public List<Item> populateItems() {
return itemService.findAll();
}
#RequestMapping(value = {"/image/{id}", "image/{id}"})
#ResponseBody
public byte[] showImage(#PathVariable("id") String id) {
return itemService.getItem(id).getImage();
}
#RequestMapping(value = {"", "/"}, method = RequestMethod.GET)
public String showAllItems() {
return "itemList";
}
#RequestMapping(value = {"add", "/add"}, method = RequestMethod.GET)
public String showItemAddForm(Model model) {
model.addAttribute("item", new Item());
return "itemAddForm";
}
#RequestMapping(value = {"add", "/add"}, method = RequestMethod.POST)
public String processAddItem(
#ModelAttribute("item") #Valid Item item,
RedirectAttributes model,
BindingResult errors,
SessionStatus session) {
if (errors.hasErrors()) {
return "itemAddForm";
}
itemService.saveItem(item);
session.setComplete();
model.addFlashAttribute("message", "Item has been added");
return "redirect:/item";
}
}
Is any wrong with the controller? How should I to make Bean Validation works with Spring and Thymeleaf?