While trying to upgrade an app to latest master, I notice a difference in form error handling. Let take this Twig template code:

{{ form_row(form) }}
{{ form_widget(form.child.subchild) }}
{{ form_errors(form.child.subchild) }}
{{ form_rest(form) }}

As a result, errors attached to form.child aren't rendered. Thus, {{ form_errors(form.child) }} needs to be added explicitly, which was not necessary before.