ZFS: i/o error - all block copies unavailable after upgrading to r225312

hi,
I'm running FreeBSD-CURRENT r224522M installed on ZFS Root and GPT
partitions and this setup is running fine. Today I've updated to r225312 and
after rebooting I've got following error message from boot loader:

ZFS: i/o error - all block copies unavailable

Then I did "zfs rollback" using rescue disk to previous revision and I was able to
boot.
Steps I did to update system:

zfs snapshot 
make buildworld
make buildkernel
make installkernel
reboot
can't boot
zfs rollback using rescue disk
boot to previous revision (r224522M).

Are there any more steps required for this procedure to work?
My previous updates from source on the same setup where successfull, this is
the first time I've encountered this error message when upgrading from source.

My setup:
gpart show 
=>       34  250069613  ada0  GPT  (119G)
         34        128     1  freebsd-boot  (64k)
        162       1886     5  bios-boot  (943k)
       2048   16777216     2  !0fc63daf-8483-4772-8e79-3d69d8477de4  (8.0G)
   16779264   33554432     3  freebsd-ufs  (16G)
   50333696  199735951     4  freebsd-zfs  (95G)

Partitions 3 and 4 are separate zfs pools (3 is geli encrypted and 4 is for
operating system).  

zfs list
NAME                        USED  AVAIL  REFER  MOUNTPOINT
home                       10,4G  5,24G  10,4G  /home
zroot                      90,2G  3,27G  1,16G  legacy

/etc/fstab
# Device		Mountpoint	FStype	Options			Dump	Pass#
zroot			/		zfs	rw,noatime		0	0
/dev/acd0		/cdrom		cd9660	ro,noauto		0	0
proc 			/proc 		procfs 	rw 			0	0

best regards,
-- 
Sebastian Chmielewski * jid:chmielsster_at_gmail.com * gg:3336919 * icq:224161389