After Upgrading Concrete5 site from 18.104.22.168 to 22.214.171.124, the footer only appears on some pages.
I've also attempted to clear the cache manually, though the CMS & via the browser, but still no luck.
<div id="sidebar" class="col_3 omega"> <?php $as = new Area('Sidebar'); $as->display($c); ?> </div><!-- #sidebar ends -->
Removing the above brings the footer back, but obviously removes the sidebar.
 There could also be broken HTML if the full footer is not included[/edit]
Have a look at what Greek Yogurt does for header/footer inclusion and compare that to your theme.
For details, probably best to read back through release notes of all the intervening versions.
Code seems pretty much the same between the Slate theme and the Greek Yogurt theme.
 Seems like everything AFTER the Sidebar is removed, assuming issue lies with the Sidebar itself. [/edit]
Theme used is:https://www.concrete5.org/marketplace/themes/slate...
Did you ever get this figure out?