i'm using Symfony 3.3.9 and when I'm trying to render a form I have the following error:
An exception has been thrown during the rendering of a template ("Unable to render the form because the block names array contains duplicates: "_fos_user_registration_form_errors", "user_errors", "user_errors", "fos_user_registration_errors", "form_errors".").
Thank you in advance for your help !
EDIT 17/09/2017 Here you go:
public function indexAction()
{
    /** @var $formFactory FactoryInterface */
    $formFactory = $this->get('fos_user.registration.form.factory');
    $form = $formFactory->createForm();
    return $this->render('AppTMMainBundle:Default:index.html.twig', array(
        'form' => $form->createView(),
    ));
}
My Twig:
{{ form_start(form, {'method': 'post', 'action': path('fos_user_registration_register')}) }}
<div class="card-content">
    <h3 class="text-center title" style="color: #3C4858;margin:10px 0;">Inscription</h3>
    <div class="social text-center">
        <a class="btn btn-just-icon btn-round btn-facebook" href="{{ path('hwi_oauth_service_redirect',{'service': 'facebook'}) }}">
            <i class="fa fa-facebook"> </i>
        </a>
        <a class="btn btn-just-icon btn-round btn-twitter" href="{{ path('hwi_oauth_service_redirect',{'service': 'twitter'}) }}">
            <i class="fa fa-twitter"></i>
        </a>
        <a class="btn btn-just-icon btn-round btn-google" href="{{ path('hwi_oauth_service_redirect',{'service': 'google'}) }}">
            <i class="fa fa-google-plus"></i>
        </a>
    </div>
    <p class="description text-center">Ou de façon plus classique</p>
    <div class="row">
        <div class="col-xs-6">
            {{ form_label(form.firstname) }}
            {{ form_widget(form.firstname) }}
        </div>
        <div class="col-xs-6">
            {{ form_label(form.lastname) }}
            {{ form_widget(form.lastname) }}
        </div>
    </div>
    <div class="row">
        <div class="col-xs-12">
            {{ form_label(form.email) }}
            {{ form_widget(form.email) }}
        </div>
    </div>
    <div class="row">
        <div class="col-xs-6">
            {{ form_widget(form.plainPassword.first, {'attr': {'class': 'form-control', 'placeholder': 'form.password'}}) }}
        </div>
        <div class="col-xs-6">
            {{ form_widget(form.plainPassword.second, {'attr': {'class': 'form-control', 'placeholder': 'form.password_confirmation'}}) }}
        </div>
    </div>
    <!-- If you want to add a checkbox to this form, uncomment this code -->
    <div class="input-group">
        <div class="checkbox">
            <label>
                <input type="checkbox" name="optionsCheckboxes" checked="">
                {{ 'index.proceed.agree'|trans }}  <a href="{{ path('tm_main_policies_terms') }}">{{ 'index.proceed.cgu'|trans }}</a>.
            </label>
        </div>
    </div>
    <div class="footer text-center">
        <input type="submit" class="btn btn-primary btn-round" value="{{ 'index.action.subscribe'|trans }}">
    </div>
</div>
{{ form_end(form) }}

 
     
    