title: Non-existent service "fos_user.user_provider.username_email"
body: <p>I am following the guide to install FOSUserBundle located at <a href="https://github.com/FriendsOfSymfony/FOSUserBundle/blob/master/Resources/doc/index.md" rel="nofollow">https://github.com/FriendsOfSymfony/FOSUserBundle/blob/master/Resources/doc/index.md</a> </p>
  
  <p>My security file:</p>
  
  <pre><code>security:
      encoders:
          FOS\UserBundle\Model\UserInterface: sha512
  
      role_hierarchy:
          ROLE_ADMIN:       ROLE_USER
          ROLE_SUPER_ADMIN: [ROLE_USER, ROLE_ADMIN, ROLE_ALLOWED_TO_SWITCH]
  
      providers:
          fos_userbundle:
              id: fos_user.user_provider.username_email
  
      firewalls:
          dev:
              pattern:  ^/(_(profiler|wdt)|css|images|js)/
              security: false
  
          main:
              pattern: ^/
              form_login:
                  provider: fos_userbundle
                  csrf_provider: form.csrf_provider
              logout:       true
              anonymous:    true
  
      access_control:
          - { path: ^/admin/, role: ROLE_ADMIN }
  </code></pre>
  
  <p>however after doing all steps, I am getting one error:</p>
  
  <pre><code>ServiceNotFoundException: The service "security.authentication.manager" has a dependency on a non-existent service "fos_user.user_provider.username_email".
  </code></pre>
  
  <p>What could be causing it?</p>