templates/bundles/TwigBundle/Exception/error.html.twig
{% extends 'base.html.twig' %}
{% block body %}
<main class="col-sm-12 justify-content-center">
<table class="table text">
<tr class="tabletop">
<td class="text-center"><b>Unknown Error</b></td>
</tr>
<tr>
<td class="text-center">
Unknown error occurred, please try again later...
</td>
</tr>
</table>
</main>
{% endblock %}