ntpd launched from rc.conf during boot get message about
/var/db/ntpd.lead-seconds.list: loaded, expire=2017-12-28.
Could this have been solved in the final release of 12.0 or be a local problem with your installation? For me, ntpd shows the following during startup on 12.0-RELEASE:
ntpd: leapsecond file ('/var/db/ntpd.leap-seconds.list'): good hash signature
ntpd: leapsecond file ('/var/db/ntpd.leap-seconds.list'): loaded, expire=2019-06-28T00:00:00Z last=2017-01-01T00:00:00Z ofs=37
I recently reinstalled my system from the 12.0-RELEASE image. Indeed the provided ntpd.lead-seconds.list is expired. However, you can easily update it using "service ntpd onefetch". Also, this is typically performed automatically once a day by /etc/periodic/daily/480.leapfile-ntpd, so I think it's mostly a cosmetic issue.
Closing as Overcome by Events. 12.0 is already released and there are clear instructions how to fix "leapfile expired" errors in ntpd.