Thymeleaf Could not bind form errors using expression "*" - spring

Question

I use Spring-boot and Thymeleaf template engine and I try use th:classappend attribute for adding optional "has-error" class for < div > html tag using #fields.hasErrors('*') expression
<form method="POST" action="/registration" class="form-signin">
<h2 class="form-signin-heading">Create your account</h2>
<div class="form-group" th:classappend="${#fields.hasErrors('*')} ? 'has-error' : ''">
<input name="username" type="text" class="form-control" placeholder="Username" autofocus="true"/>
<p class="alert alert-danger" th:if="${#fields.hasErrors('username')}" th:errors="*{username}"></p>
</div>
<div class="form-group" th:classappend="${#fields.hasErrors('*')} ? 'has-error' : ''">
<input name="password" type="text" class="form-control" placeholder="Password" autofocus="true"/>
<p class="alert alert-danger" th:if="${#fields.hasErrors('password')}" th:errors="*{password}"></p>
</div>
<div class="form-group" th:classappend="${#fields.hasErrors('*')} ? 'has-error' : ''">
<input name="passwordConfirm" type="text" class="form-control" placeholder="Confirm your password" autofocus="true"/>
<p class="alert alert-danger" th:if="${#fields.hasErrors('passwordConfirm')}" th:errors="*{passwordConfirm}"></p>
</div>
<button class="btn btn-lg btn-primary btn-block" type="submit">Submit</button>
</form>
but I have this error
Could not bind form errors using expression "*". Please check this
expression is being executed inside the adequate context (e.g. a
with a th:object attribute)
my controller methods
#RequestMapping(value = "/registration", method = RequestMethod.GET)
public String registration(Model model) {
model.addAttribute("userForm", new User());
return "registration";
}
#RequestMapping(value = "/registration", method = RequestMethod.POST)
public String registration(#ModelAttribute("userForm") User userForm, BindingResult bindingResult, Model model) {
userValidator.validate(userForm, bindingResult);
if (bindingResult.hasErrors()) {
return "registration";
}
userService.save(userForm);
securityService.autologin(userForm.getUsername(), userForm.getPasswordConfirm());
return "redirect:/welcome";
}
what am I doing wrong?

Answer 1

I just add th:object="${userForm} attribute to my form element. And now it work fine!