{% extends "@FOSUser/layout.html.twig" %}

{% block fos_user_content %}
{% include "register_content.html.twig" %}
{% endblock fos_user_content %}

{% extends "@FOSUser/layout.html.twig" %}

{% block fos_user_content %}
{% include "@FOSUser/Registration/register_content.html.twig" %}
{% endblock fos_user_content %}

Fix twig reference for templates
Fix twig reference for templates