Symfony2.4 form 'This form should not contain extra fields' error

If you want the validator to ignore additional fields you should try passing 'allow_extra_fields' => true as an option to the FormBuilder.

Its because when you are generating the form you are adding submit buttons but when you are validating them you are not. try:

public function cpostAction(Request $request){    $entity = new Task();    $form = $this->createForm(new TaskType(), $entity)->add('submit','submit');    ...

The submit button is technically a field even though symfony wont map it to an entity property by default. So when you generate the form with a submit button and then submit that form the form you generate in your validation controller action needs to also have a submit button.

If you wanna disable fields validation, you must add

public function setDefaultOptions(\Symfony\Component\OptionsResolver\OptionsResolverInterface $resolver){    $resolver->setDefaults(array(        'csrf_protection' => false,        'validation_groups' => false,    ));}

And in buildForm method:

    public function buildForm(FormBuilderInterface $builder, array $options) {        $builder->addEventListener(FormEvents::POST_SUBMIT, function ($event) {            $event->stopPropagation();        }, 900);        $builder->add('field1','text')                ->add('field2','text')                .                .                .    } 

For more details: http://symfony.com/doc/current/cookbook/form/dynamic_form_modification.html#cookbook-dynamic-form-modification-suppressing-form-validation