symfony3 – Авторизация Symfony 3.0 – Stack Overflow на русском

Приветствую всех. Помогите, пожалуйста, разобраться и найти ошибку. Пытаюсь настроить авторизацию для админов сайта. Админов храню в базе. Делаю все по документации но авторизоваться никак не получается. При попытке авторизоваться отправляется форма и ничего не происходит.

#security.yml

security:
    encoders:
        AppMainBundleEntityUser:
            algorithm: bcrypt

    role_hierarchy:
        ROLE_ADMIN:       ROLE_USER
        ROLE_SUPER_ADMIN: [ROLE_USER, ROLE_ADMIN, ROLE_ALLOWED_TO_SWITCH]

    providers:
        main_db_provider:
            entity:
                class: AppMainBundle:User
                property: username
                manager_name: ~

    firewalls:
        dev:
            pattern:  ^/(_(profiler|wdt)|css|images|js)/
            security: false

        login_firewall:
            pattern:    ^/admin/login$
            anonymous:  ~

        main:
            pattern:    ^/
            form_login:
                check_path: app_main_admin_login
                login_path: app_main_admin_login
                always_use_default_target_path: true
                default_target_path: app_main_admin_products_list
            logout:
                path:   main_admin_logout
                target: app_main_homepage
            anonymous: ~
            provider: main_db_provider
    access_control:
        - { path: ^/admin/login, roles: IS_AUTHENTICATED_ANONYMOUSLY }
        - { path: ^/admin, roles: ROLE_ADMIN }

#AppMainBundle/Entity/User

<?php

namespace AppMainBundleEntity;

use DoctrineORMMapping as ORM;
use SymfonyComponentSecurityCoreUserUserInterface;

/**
 * User
 *
 * @ORMTable(name="users")
 * @ORMEntity(repositoryClass="AppMainBundleRepositoryUserRepository")
 */
class User implements UserInterface, Serializable
{
    /**
     * @ORMColumn(type="integer")
     * @ORMId
     * @ORMGeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @ORMColumn(type="string", length=25, unique=true)
     */
    private $username;

    /**
     * @ORMColumn(type="string", length=64)
     */
    private $password;

    /**
     * @ORMColumn(name="is_active", type="boolean")
     */
    private $isActive;

    /**
     * User constructor.
     */
    public function __construct()
    {
        $this->isActive = true;
    }

    /**
     * @return mixed
     */
    public function getUsername()
    {
        return $this->username;
    }

    /**
     * @return null
     */
    public function getSalt()
    {
        return null;
    }

    /**
     * @return mixed
     */
    public function getPassword()
    {
        return $this->password;
    }

    /**
     * @return array
     */
    public function getRoles()
    {
        return array('ROLE_ADMIN');
    }

    public function eraseCredentials()
    {
    }

    /** @see Serializable::serialize() */
    public function serialize()
    {
        return serialize(array(
            $this->id,
            $this->username,
            $this->password,
        ));
    }

    /** @see Serializable::unserialize() */
    public function unserialize($serialized)
    {
        list (
            $this->id,
            $this->username,
            $this->password,
        ) = unserialize($serialized);
    }
}

# AppMainBundle/Controller/SecurityController

<?php

namespace AppMainBundleController;

use SymfonyBundleFrameworkBundleControllerController;
use SymfonyComponentHttpFoundationRequest;
use SensioBundleFrameworkExtraBundleConfigurationTemplate;
use SymfonyComponentSecurityHttpAuthenticationAuthenticationUtils;

class SecurityController extends Controller
{
    /**
     * @var AuthenticationUtils
     */
    private $authenticationUtils;

    /**
     * SecurityController constructor.
     * @param AuthenticationUtils $authenticationUtils
     */
    public function __construct(AuthenticationUtils $authenticationUtils)
    {
        $this->authenticationUtils = $authenticationUtils;
    }

    /**
     * @Template("AppMainBundle:Auth:login.html.twig")
     *
     * @param Request $request
     * @return array
     */
    public function loginAction(Request $request)
    {
        $error = $this->authenticationUtils->getLastAuthenticationError();
        $lastUsername = $this->authenticationUtils->getLastUsername();

        return [
            'last_username' => $lastUsername,
            'error'         => $error,
        ];
    }
}

# login form

{% extends 'AppMainBundle::layout.html.twig' %}

{% block content %}

    {% if error %}
        <div>{{ error.messageKey|trans(error.messageData, 'security') }}</div>
    {% endif %}

    <div class="content login">
        <form action="{{ path('app_main_admin_login') }}" method="post" class="login__form">
            <div class="login__inner">
                <label class="login__form__label text" for="username">Логин</label><!--
             --><input class="login__form__inp"
                       type="text"
                       id="username"
                       name="_username"
                       placeholder="Логин"
                       value="{{ last_username }}"/>
            </div>
            <div class="login__inner">
                <label class="login__form__label text" for="password">Пароль</label><!--
             --><input class="login__form__inp"
                       type="password"
                       id="password"
                       placeholder="Пароль"
                       name="_password"/>
            </div>
            <div class="login__inner">
                <button class="login__form__btn" type="submit">Войти</button>
            </div>
        </form>
    </div>

{% endblock %}

#routings

app_main_admin_login:
    path:     /admin/login
    defaults:  { _controller: app_main.security_controller:loginAction }