The last few times I've upgraded the server using the Debian packages, I'm getting errors at the end of the process. I don't think they all refer to the same file, but they're similar in form.

The latest one:

Setting up logitechmediaserver (7.9.1~1510044676) ...
chown: cannot access '/var/lib/squeezeboxserver/cache/PluginCache-SQLPlayList.db-wal': No such file or directory
dpkg: error processing package logitechmediaserver (--install):
 subprocess installed post-installation script returned error exit status 1
Processing triggers for systemd (232-25+deb9u1) ...
Errors were encountered while processing:
The file referenced doesn't seem to exist when the server isn't running, but is created when it's running:

root@xcp-media:~# ls -l /var/lib/squeezeboxserver/cache/PluginCache-SQLPlayList.db*
-rw-r--r-- 1 squeezeboxserver nogroup 175104 Nov  8 09:28 /var/lib/squeezeboxserver/cache/PluginCache-SQLPlayList.db
-rw-r--r-- 1 squeezeboxserver nogroup  32768 Nov  8 09:28 /var/lib/squeezeboxserver/cache/PluginCache-SQLPlayList.db-shm
-rw-r--r-- 1 squeezeboxserver nogroup 264128 Nov  8 09:28 /var/lib/squeezeboxserver/cache/PluginCache-SQLPlayList.db-wal
Not the end of the world, just meant this time I had to manually start the server (it was stopped to upgrade, but never restarted).