It's been a while since I've updated my Kunena plugin for ES, so I decided to remove the old one and install a new version from the
app section (version 1.0.216). When I try to upload the zip file it says "Warning JInstaller: :Install: Cannot find Joomla XML setup file".
Perhaps something in the xml file? Feel free to test it on my test site if you cannot replicate the install issue on your end. For now I don't have the Kunena plugin installed. The good news is that I did not attempt to install this update on my real site.