ZFS crash on mountroot after removal of slog device

[Mike Selner]

Hello,
I have a FreeBSD 10.3 system with all filesystems on ZFS (except some tmp on SSD).

I have L2ARC and SLOG on SSD. The SSD started reporting SMART errors so I removed the L2ARC device which worked fine.  Then I removed the SLOG device using:

zpool remove zroot gpt/ssdslog0

The system returned to the # prompt but a few minutes later the system panicked and and rebooted. After reboot it fails to mount root fs, giving the message:

Trying to mount root from zfs:zroot/ROOT/default [ ]...
panic: solaris assert: nvlist_lookup_uint64(configs[ i], ZPOOL_CONFIG_POOL_TXG, &txg) == 0, file: /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/spa.c, line: 4039
cpuid = 4

Short version: I can import the pool using fixit on an install memstick, but can not get the system to mountroot when booting from this pool.

Full details at https://forums.freebsd.org/threads/59006/.

Please advise if I should also post full details here.

Thank you
-- 
Mike