cv_database/flask_app/app/templates/errors/404.html

{% extends 'base.html' %}

{% block content %}
<span class="title"><h2>{% block title %} 404 error - Page not found{% endblock %}</h2></span>
<div class="content-container content">
Sorry, but, that URL is not operational
</div><!-- end of div.content -->
{% endblock %}