Error in synth after upgrading from 10.4 to 12.0

[Kurt Buff - GSEC, GCIH]

All,

I just upgraded a machine from 10.4 to 12.0, using freebsd-update.
That worked fine.

I had deleted all packages using
     pkg delete -af

Then after the upgrade process I went to /usr/ports/ports-mgmt/pkg and
/usr/ports/ports-mgmt/synth, and performed "make install clean" for
each, which worked fine.

Then, I did "rehash", and then "synth install /root/pkg.txt" to get my
preferred ports installed, and receive this error.

raised REPLICANT.SCENARIO_UNEXPECTED : /usr/sbin/mtree -p
/usr/obj/synth-live/SL09/var -f /etc/mtree/BSD.var.dist -deqU =>
failed (exit code not 0

I was able to install the ports manually by visiting each directory
and installing the ports manually with "make clean" then "make install
clean", but I don't find anything via STFW for the above error.

Anyone have a clue for me?

Kurt