Spring 2 + Thymeleaf + Validation = Whitelabel Error Page 500 - validation

Question

I'm trying to validate my form input, but after its submit it does not load my controller method, instead it shows a Whitelabel Error Page with Internal Server Errorand status 500 but with the correct validation errors.
I know it must be a matching issue with the expected parameters of my method, but so far from what I've gathered the rule is simply BindingResult then Model which I did but it still does not trigger my controller method...
Any thoughts are appreciated.
Controller-Method, that is not triggered unfortunately:
#Controller
#Validated
public class UserController {
#PostMapping("/users/add")
def String usersAdd(#Valid #ModelAttribute("user") User user, BindingResult bindingResult, Model model) {
if (bindingResult.hasErrors()) {
return "userAdd"
} else {
userRepository.save(user)
return "usersList"
}
}
Template-Form:
<form action="#" th:action="#{/users/add}" th:object="${user}" method="post">
<div class="form-row">
<div class="form-group col-md-12">
<input type="text" class="form-control" th:field="*{name}">
<div th:if="${#fields.hasErrors('name')}" th:errors="*{name}">Name Error</div>
</div>
</div>
<div class="form-row">
<div class="form-group col-md-6">
<button type="submit" class="btn btn-success">Add</button>
</div>
</div>
</form>
Model-Class:
#Document(collection = "users")
public class User {
#Id
String id
#Size(min=3, max=100)
String name
}
Update:
Went debugging and found this part, so it seems it's invoking with the correct parameters. I am new to Spring, so I'm having difficulties thinking about other "newbie"-problems.
in InvocableHandlerMethod.java the method DoInvoke is called on my usersAdd with Station, BeanPropertyBindingResult, BindingAwareModelMap.
When Invoking the method it causes a ConstraintViolationException which will abort invocation, is this expected?

Answer 1

I figured it out after a looong debug session. The #Valid before my User user causes a ConstraintViolationException, which will, expectedly, abort the invocation of my usersAdd because, as expected, the parameter is not valid.
And the reason for this behaviour was the #Validated at the controller class, which I picked up from some tutorial, but when removed everything works and validates as expected.
I guess I was checking a REST-Tutorial and tried to use their approach... not the best idea ;)