It turns out that using Jetty as the underlying servlet container would not work: I would get an obscure Java exception during various operations:
Switching to Tomcat 8 worked.
Changing filesystem charset to UTF-8
I had been using ISO-8859-15 filenames for ever. As part of the OS ugprade, I decided it was more than time to switch the whole system to UTF-8. (One specific issue that prompted this was the fact that GDM now seems to not support ISO 8859-15 GECOS user names anymore).
In order to have Subsonic properly handle file and directory names encoded in UTF-8, I had to set LANG for it:
and to re-create the database from scratch (remove everything from