Can't boot ZFS: invalid zap_type

[Tim Bishop]

I'm having trouble booting from a ZFS pool. I get the following error at
boot time:

ZFS: invalid zap_type=134218628

I have my root fs on ZFS, and I'm using gptzfsboot. The machine is on
RELENG_8.

I'd been having some performance problems so I tried rolling back
RELENG_8 to the start of the month. It hasn't booted since I did that.

I can boot from a live cd and I can import and read the pool. I brought
the OS back to the latest RELENG_8 too, but that didn't help.

Any suggestions?

As an aside, and this isn't meant to be too negative, I've been having a
lot of issues with gptzfsboot. It's been fine for ages, but as soon as
I've started changing disks or putting the disks in another machine,
I've had lots of problems (mostly the "all block copies unavailable"
error). It seems gptzfsboot does its job fine but is quite easy to
break if things aren't exactly how it expects.

Tim.

-- 
Tim Bishop
http://www.bishnet.net/tim/
PGP Key: 0x5AE7D984