[SOLVED] mythbackend works manually but not at boot

I just ran into this and wanted to post my solution in case anyone else has the same problem.

Just installed mythbuntu onto a new 16.04 install and got mythbackend to run happily when I launched it, but it wouldn't be ruing after I rebooted.

Looking at syslog and mythtv/mythbackend.log, I saw it was a permissions issue. When I launched it, mythbackend used the /home/fred/.mythtv/config.xml (~/.mythtv/config.xml universally) file.
But at boot, mythbackend was using /home/mythtv/.mythtv/config.xml
So I deleted /home/mythtv/.mythtv/config.xml and linked the working xml file to the other location with:

sudo ln -s /home/fred/.mythtv/config.xml /home/mythtv/.mythtv/config.xml