notifications-admin/app/templates/error/500.html

{% extends "admin_template.html" %}
{% block page_title %}Server error{% endblock %}
{% block fullwidth_content %}
    <div class="grid-row">
      <div class="column-two-thirds">
        <h1>500</h1>
        <p>Sorry, something went wrong on our system.</p>
      </div>
    </div>
{% endblock %}