Re: System not booting after upgrade 14.3->14.4 with "ZFS: unsupported feature: com.klarasystems: vdev_zaps_v2"

In reply to: Johan Helsingius : "Re: System not booting after upgrade 14.3->14.4 with "ZFS: unsupported feature: com.klarasystems: vdev_zaps_v2""
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From: Frank Leonhardt <freebsd-doc_at_fjl.co.uk>
Date: Sat, 02 May 2026 19:45:56 UTC

On 02/05/2026 17:39, Johan Helsingius wrote:
> <snip>

> i am the only user, and I haven't installed any custom patches,
> just kept doing freebsd-updates since initial install many years
> ago.
>
That's really weird, but I'm glad freebsd-update fixed it.

I checked and apparently TrueNAS doesn't use any weird Klana ZFS so my 
guess there was wrong. In fact, having RTFM it's part of OpenZFS.

https://openzfs.github.io/openzfs-docs/man/master/7/zpool-features.7.html#com.klarasystems:vdev_zaps_v2

I did some more digging and it was added to OpenZFS 2.2

More info here: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=275199

Looks like my guess about the bootloader may have been correct, partly 
by luck!  (i.e. it was for a pre-2.2 pool).

Regards, Frank.