I’m new in spring framework and have some problems.I have no idea why my errors cannot be passed with redirect attributes to thymeleaf.

I want to validate my form input in Thymeleaf but I can’t see error messages in my view. I can see every message from BindingResults in debugger mode by I can’t figure out why I can’t see it in my template.

Here are my Model and Controller:

Model —>

public class UserAddBindingModel {     @NotBlank(message = "Username is required.")     private String username;     @NotBlank(message = "First Name is required.")     private String firstName;     @NotBlank(message = "Last Name is required.")     private String lastName;       public UserAddBindingModel() {     }      public String getUsername() {         return username;     }      public void setUsername(String username) {         this.username = username;     }      public String getFirstName() {         return firstName;     }      public void setFirstName(String firstName) {         this.firstName = firstName;     }      public String getLastName() {         return lastName;     }      public void setLastName(String lastName) {         this.lastName = lastName;     }  } 

Controller —->

@GetMapping("register")     public ModelAndView registerUser(ModelAndView modelAndView,RedirectAttributes redirectAttributes, @ModelAttribute("userAddBindingModel") UserAddBindingModel userAddBindingModel) {         modelAndView.setViewName("auth-register");         if (modelAndView.getModel().containsKey("errors")) {             System.out.println();         }           return modelAndView;     }      @PostMapping("register")     public ModelAndView registerUserConfirm(ModelAndView modelAndView,                                             @ModelAttribute("userAddBindingModel") @Valid UserAddBindingModel userAddBindingModel,                                             BindingResult bindingResult,                                             RedirectAttributes redirectAttributes) {          if (bindingResult.hasErrors()) {             modelAndView.setViewName("redirect:register");             redirectAttributes.addFlashAttribute("userAddBindingModel",userAddBindingModel);             redirectAttributes.addFlashAttribute("org.springframework.validation.BindingResult.userAddBindingModel",bindingResult);            // modelAndView.addObject("errors",bindingResult.getAllErrors());         } else {             modelAndView.setViewName("redirect:/");             this.userService.registerUser(this.modelMapper.map(userAddBindingModel, UserServiceModel.class));         }         return modelAndView;     } 

And finally the view ->

<form th:object="${userAddBindingModel}"  action="/users/register"  method="POST" class="main-form mx-auto col-md-8 d-flex flex-column justify-content-center">             <div class="row">                 <div  class="form-group col-md-6 mb-3">                     <label for="firstName" class="text-white font-weight-bold">First Name</label>                     <input th:field="*{firstName}"   id="firstName" type="text" min="2" max="20" class="form-control"                            placeholder="First name" th:errorclass="field-error"  />                      <p th:if="${#fields.hasErrors('firstName')}" th:errors="*{firstName}"                        class="errors alert alert-danger">                         First name is required.                     </p>                  </div>                 <div class="form-group col-md-6 mb-3">                     <label for="lastName" class="text-white font-weight-bold">Last Name</label>                     <input th:field="*{lastName}" id="lastName" type="text" min="2" max="20" class="form-control"                            placeholder="Last name" />                     <p class="errors alert alert-danger">                         Last name is required.                     </p>                 </div>  </form>             

it does not display any error.Am I missing something? Thanks in advance :).