Symfony2: FOSUserBundle remove "Edit Username" form field in profile

Question

I am trying to remove the option to edit the username in the FOSUserBundle.

My ProfileFormType.php looks as follows:

<?php

namespace ACME\MemberBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;
use Symfony\Component\Security\Core\Validator\Constraint\UserPassword as OldUserPassword;
use Symfony\Component\Security\Core\Validator\Constraints\UserPassword;

use FOS\UserBundle\Form\Type\ProfileFormType as BaseType;

class ProfileFormType extends BaseType {
    protected function buildUserForm(FormBuilderInterface $builder, array $options) {
        parent::buildUserForm($builder, $options);      
        $builder->remove('username');
    }

    public function getName()
    {
        return 'acme_member_edit_profile';
    }
}

I also registered it as service and edited the config.yml file. However, when I submit the form I get the following alert message:

This form should not contain extra fields.

Answer 1

I found the solution myself:

I have also extended the ProfileController where I used the username parameter from the POST-request. Since this parameter was missing now, I got this message.