php: the form view data is expected to be an instance of the App Entity SubmitNew class

Hell, I want to learn something about Symfony and I want to create a simple form that allows users to add text to the database.

The error that comes to me is this:

The form view data is expected to be an instance of the App Entity SubmitNew class, but it is a (n) string. You can avoid this error by setting the "data_class" option to null or by adding a view transformer that transforms a string to an instance of App Entity SubmitNew.

Here are my classes.

Controller.php

                {
$ form = $ this-> createForm (SubmitNewType :: class, SubmitType :: class);

returns $ this-> render (& # 39; submit_new / index.html.twig & # 39 ;, [
            'form' => $form->createView()
        ]);
}

SendNewType.php

{
public function buildForm (FormBuilderInterface $ builder, array $ options)
{
$ builder
-> add (& # 39; question & # 39;)
-> add (& # 39; answer & # 39;)
;
}

public function configureOptions (OptionsResolver $ solve)
{
$ solve-> setDefaults ([
            'data_class' => SubmitNew::class,
        ]);
}
}

I'm not sure what I'm doing wrong, since I do not have any syntax errors of any kind.

Could someone please explain what I'm doing wrong?

Here is my html.twig

{% extends & # 39; base.html.twig & # 39;%}

{% block title%} Hello {% endblock%}

{% block body%}
{{form (form)}}
{% endblock%}


Thank you for your patience.