I’ve had this problem at least since leap 42.2 and it is on 5 machines. /var/log/messages gets an entry which reads:
WARNING: Default value changed for the prefix() option of systemd-journal source in syslog-ng 3.8; old_value=’’, new_value=’.journald.’
However I can’t find anything about systemd-journal in the syslog-ng configuration so I canm’t work out where it wants me to change the prefix to avoid this message, which I realise isn’t critical in the grand scheme of things.
You can safely ignore it. You most likely use the system() source, which automatically finds local log source, the journal source in case of recent openSUSE releases.
The journal contains many additional name-value pairs about log messages. From version 3.8 these are available with the “.journald.” prefix.