RELENG_13 to 14 upgrade fail

On one of my VMs that I upgraded from RELENG_13 to RELENG_14, I forgot 
to update the boot loader so now at bootup, I have
ZFS: unsupported feature: com.klarasystems:vdev_zaps_v2

Can't find /boot/zfsloader

What is the best way to recover from this ? Its a raw vm image. gpart is 
p1=freebsd-boot, p2=freebsd-swap,p3=freebsd-zfs

I was thinking perhaps start up a second vm thats RELENG_14, mdconfig 
the image, and then what do I need to do ? Just

gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 md0 ?

     ---Mike