Q: Unknown tag name "form_rest" I'm having trouble making a form to work using Twig and Sf2.
Unknown tag name "form_rest" in MyBundle:Default:home.html.twig at line 40

In the view it reads:
{% form_rest(form) %}

I can try any form* methods. Same result.
The controler has something like this:
public function userEmailAddressFormAction()
{
  $userEmailAddress = new UserEmailAddress();
  $form = $this->createForm(new UserEmailAddressType(), $userEmailAddress);

  return $this->render('MyBundle:Default:userEmailAddress.html.twig', array('form' => $form->createView()));
}

Why isn't Twig loading the helper?

A: It's not a tag; it's a function. So, use {{ and }} instead of {% and %}:
{{ form_rest(form) }}

