We have four *NAS systems in our infrascruture: TrueNAS HA 9.10, FreeNAS Certificed 9.10, then a pair of FreeNAS Certified with recent upgrades from 9.10 to 12.0-BETA (by way of 9.10 latest -> 11.1 -> 11.3).
Now, both legacy FreeNAS 9.10 and TrueNAS 9.10 systems could no longer push replication shapshots.
~# python /usr/local/www/freenasUI/tools/autorepl.py warning: cannot send 'email@example.com': signal received cannot send 'tank/cifs/tree': I/O error
Checked /var/log/debug.log and found the following:
freenas autorepl.py: [tools.autorepl:157] Replication result: /sbin/zfs: Command not found.
It seems that *NAS 9.10 calls for "/sbin/zfs" on the far-side but this no longer exists in TrueNAS-12-0-BETA. Instead it is at /usr/local/sbin/zfs.
Mitigated with symlink from /usr/local/sbin/zfs to /sbin/zfs
ln -s /usr/local/sbin/zfs /sbin/zfs