netbox-community-netbox/netbox/templates/404.html

{% extends 'base/40x.html' %}
{% load i18n %}

{% block title %}{% trans "Page Not Found" %}{% endblock %}

{% block icon %}<i class="mdi mdi-alert"></i>{% endblock %}

{% block message %}
    {% trans "The requested page does not exist" %}.
{% endblock %}