flask-boilerplate/app/templates/error.html

{% extends "layout.html" %}

{% block head %}
    {{ super() }}
{% endblock %}

{% block content %}

    <div class="error-box" align="center">
        <img class="ui medium image error-image" src="{{ url_for('static', filename='img/error.png') }}">
        <h1 class="ui header">{{ message }}<h1>
    </div>

{% endblock %}