Record not found in table users with primary key ['6']


well I’m post data json to my backend and I have this error:

  "message": "Record not found in table \"users\" with primary key ['6']",
  "url": "/users/userdata",
  "code": 404

I don’t know why? I have a user with id = 6 in my database, in my function I recieve the data and id correctly, check this part, my controller:
public function userdata()
$user = TableRegistry::get(‘Users’);
$id = $this->request->getData(‘iduser’);

        $data = $user->get($id, [
            //'contain' => ['Cities']

            'success' => true,
            'data' => $data,
            '_serialize' => ['success', 'data']

Try this with $this->Users->get($id) and $this->Users->find($id) I always get the same error