FOSUserBundle how to extend handler correctly - symfony

Question

It throws this error:
Unrecognized option "handler" under "fos_user.registration.form"
And the files are:
//services.yml
app.form.registration:
class: AppBundle\Form\AccomodationFrontSignUpType
tags:
- { name: form.type, alias: app_user_registration }
app.form.handler.registration:
class: AppBundle\Form\Handler\RegistrationFormHandler
arguments: ["#fos_user.registration.form", "#request", "#fos_user.user_manager", "#fos_user.mailer", "#fos_user.util.token_generator"]
scope: request
public: false
//config.yml
fos_user:
db_driver: orm
firewall_name: main
user_class: AppBundle\Entity\User
group:
group_class: AppBundle\Entity\Group
service:
mailer: swiftmailer.mailer.strato
from_email:
address: webmyhomepage#strato.com
sender_name: myHomepage
registration:
form:
handler: app.form.handler.registration
type: app_user_registration
confirmation:
template: FOSUserBundle:Registration:email.txt.twig
enabled: true
Any help is welcome, thanks

Answer 1

The error means that there is an invalid parameter in your config. The key handler in your config
-> handler: app.form.handler.registration
if you take a look inside the fos user bundle DependencyInjection folder, Configuration.php file, that option does not exist. so its invalid :).
There you can see witch options are available. In my current version of this bundle i have this options available under form: type, name, validation_groups.
Also you can see the default configuration for a bundle with:
php app/console debug:config FOSUserBundle