.X, the setup utility will
            install a new, fresh copy of <span class="code">weewx.conf</span>,
            which you will then have to edit by hand. Thereafter, V2.X upgrades
            should be automatic.
        </li>
        <li>Custom services. If you have written a custom service, it will have
            to be updated to use the new engine. The overall architecture is
            very similar, except that functions must be <em>bound</em> to
            events, rather than get called impli