<form action="{{ submit_url }}" method="POST">
    {% include 'wagtailadmin/shared/non_field_errors.html' %}
    {% csrf_token %}
    {% block form_fields %}{% endblock form_fields %}
    <button type="submit" class="button {{ action_button_class }}">{{ action_button_text }}</button>
    <a href="{{ next }}" class="button button-secondary">{{ no_action_button_text }}</a>
</form>
