Description:

Lack of album art and log messages of the form:

upnphttp.c:1425: error: Rejecting wide link /var/cache/minidlna/art_cache/... -> /var/cache/private/minidlna/art_cache/...
(only diff in paths is that one includes "/private")

This is strictly an upstream bug but surfaced by the systemd unit file used in the Arch package.

Here's what's happening:

The systemd unit, minidlna.system, contains the lines:
DynamicUser=yes
CacheDirectory=minidlna

When the service is started, systemd symlinks /var/cache/minidlna -> /var/cache/private/minidlna

If the default db_dir is left commented in the minidlna.conf file as:
#db_dir=/var/cache/minidlna

Then it doesn't get resolved internally to the real path (/var/cache/private/minidlna/).
You can check the paths that are used in the db:

# sqlite3 /var/cache/minidlna/files.db
...
sqlite> .dump ALBUM_ART
...
INSERT INTO ALBUM_ART VALUES(2,'/var/cache/minidlna/art_cache/...
^D

These paths always fail the comparison test with /var/cache/private/minidlna/art_cache/...

The workaround is simply to uncomment the default in minidlna.conf:
db_dir=/var/cache/minidlna

Rebuild the cache and then you'll see paths of the form:

INSERT INTO ALBUM_ART VALUES(2,'/var/cache/private/minidlna/art_cache/...

The proper solution is to patch minidlna.conf or fix upstream.

Package version: minidlna 1.3.2-2.1