Symfony3 Security - Load User from database does not work - symfony

Question

I have a Invalid credentials error when I'm trying to load my user form the database.
Here is my security.yml
security:
providers:
database:
entity: { class: AppBundle\Entity\User, property: username }
encoders:
AppBundle\Entity\User: plaintext
firewalls:
dev:
pattern: ^/(_(profiler|wdt)|css|images|js)/
security: false
main:
anonymous: ~
# pattern: ^/
form_login:
login_path: /login
check_path: /login_check
# default_target_path: /admin
provider: database
logout:
path: /logout
target: /login
My User Entity:
<?php
namespace AppBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Security\Core\User\UserInterface;
/**
* User
*
* #ORM\Table(name="user")
* #ORM\Entity(repositoryClass="AppBundle\Repository\UserRepository")
*/
class User implements UserInterface
{
/**
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
* #ORM\Column(type="integer")
*/
private $id;
/**
* #ORM\Column(type="string", unique=true)
*/
private $username;
/**
* #ORM\Column(type="string")
*/
private $password;
/**
* #return mixed
*/
public function getId()
{
return $this->id;
}
/**
* Returns the password used to authenticate the user.
*
* This should be the encoded password. On authentication, a plain-text
* password will be salted, encoded, and then compared to this value.
*
* #return string The password
*/
public function getPassword()
{
return $this->password;
}
/**
* Set password
*
* #param string $password
*
* #return User
*/
public function setPassword($password)
{
$this->password = $password;
return $this;
}
/**
* Returns the salt that was originally used to encode the password.
*
* This can return null if the password was not encoded using a salt.
*
* #return string|null The salt
*/
public function getSalt()
{
}
/**
* Returns the username used to authenticate the user.
*
* #return string The username
*/
public function getUsername()
{
return $this->getUsername();
}
/**
* Set username
*
* #param string $username
*
* #return User
*/
public function setUsername($username)
{
$this->username = $username;
return $this;
}
/**
* Removes sensitive data from the user.
*
* This is important if, at any given point, sensitive information like
* the plain-text password is stored on this object.
*/
public function eraseCredentials()
{
// TODO: Implement eraseCredentials() method.
}
/**
* Returns the roles granted to the user.
*
* <code>
* public function getRoles()
* {
* return array('ROLE_USER');
* }
* </code>
*
* Alternatively, the roles might be stored on a ``roles`` property,
* and populated in any number of different ways when the user object
* is created.
*
* #return (Role|string)[] The user roles
*/
public function getRoles()
{
// TODO: Implement getRoles() method.
}
}
My Controllers:
/**
* #Route("/login", name="login")
*/
public function loginAction(Request $request)
{
$authenticationUtils = $this->get('security.authentication_utils');
// get the login error if there is one
$error = $authenticationUtils->getLastAuthenticationError();
// last username entered by the user
$lastUsername = $authenticationUtils->getLastUsername();
$form = $this->createForm(LoginType::class, array(
'_username' => $lastUsername,
));
return $this->render(':back/security:login.html.twig', array(
'error' => $error,
'form' => $form->createView(),
));
}
/**
* #Route("/login_check", name="login_check")
*/
public function loginCheckAction(){}
I don't understand why it does not work. I have tried to follow the documentation and make it very simple.
The user is in my database and the password is plaintext.
What did I do wrong?