When /tmp/minidlna don't exist the logfile are not created.
in line 578 to 583 in minidlna.c logfile for minidlna is created, This lines would fail when /tmp/minidlna/ does not exist. As when u restart a ubuntu system /tmp is cleared.
I have found a solution that works:
just past the following in front of line 578:
if( access(DB_PATH, F_OK) != 0 )
char *db_path = strdup(DB_PATH);
this lines is the same as the lines that is made when you check for existing database in line 680.