Failed to connect the MythTv backend with the known protocol versions.

I have been running Kodi/Openelec as a MythTV frontend since Jan 2016. Things have been running fine until I upgraded my MythTV backend/frontend machine from 14.04 to 16.04. Now my Kodi frontend complains it can’t connect with the backend. “Failed to connect the MythTv backend with the known protocol versions.”
I also had a problem that I couldn’t connect to the Myth backend using Mythweb because of mysql/php issues, which I have since fixed. See:
https://ubuntuforums.org/showthread.php?t=2342300
Also my frontend LIRC remote doesn’t work, but I assume thats not related.

I’ve checked the Mythtv backend setup to make sure the security key is 0000 and the ports match Kodi.
The Kodi Mythtv add-on is 2.8.4 and the Update menu item is greyed out, so I assume I’m up to date.
Here is a copy of the log with debbuging enabled in both the add-on and Kodi.

http://pastebin.com/FUxDpzaw

Thanks for your help!