searxng/searx/templates/oscar/messages/unknow_error.html

<div class="alert alert-danger fade in" role="alert">
    <button class="close" data-dismiss="alert" type="button">
        <span aria-hidden="true">×</span>
        <span class="sr-only">Close</span>
    </button>
    <strong>{{ _('Oh snap!') }}</strong>
    {{ _('Something went wrong.') }}
</div>