private function _retrieve_session(){
    if ( !$this->id ){
      // The user ID must be in the session
      $id_session = $this->get_id_session();
      $id = $this->get_session('id');
      if ( $id_session && $id ){
        $this->_sess_info($id_session);
        if (
          isset($this->sess_cfg['fingerprint']) &&
          ($this->get_print($this->_get_session('fingerprint')) === $this->sess_cfg['fingerprint'])
        ){
          $this
            ->_authenticate($id)
            ->_user_info()
            ->_init_dir()
            ->save_session();
        }
        else{
          $this->set_error(19);
        }
      }
      else{
        //$this->set_error(15);
      }
    }
    return $this;
  }