cakephp $this->User->save($this->data) error on edit function of a logged user
===

i'm trying to create the "edit" controller for a logged user in cakephp. This would be the function to change/add informations about the user.
I get an error during the $this->User->save($this->data) function and i don't understand what is the problem


    public function edit() {
       $this->User->id = $this->Auth->User('id');
    
        if ($this->request->is('post')) {
            if ($this->User->save($this->data)) {
                $this->Session->setFlash(__('The user has been saved'), 'flash_success');
               // $this->redirect($this->Auth->redirect());
            } else {
                var_dump($this->invalidFields());
    
                $this->Session->setFlash(__('The user could not be saved. Please, try again.'), 'flash_failure');
            }
        } else {
            //autocompleto il form
            $this->data = $this->User->read(null, $this->Auth->User('id'));
        }
    }


The view is:

    <?php 
    echo $this->Form->create('User',array('action' => 'edit'));
    echo $this->Form->input('name', array('label'=> 'Name'));
    echo $this->Form->input('surname', array('label'=> 'Surname'));
    echo $this->Form->input('id', array('type'=> 'hidden'));
    echo $this->Form->end(__('Submit')); 
    ?>
