Failure to boot after upgrade 14.3->14.4 with "ZFS: unsupported feature: com.klarasystems: vdev_zaps_v2"

[Johan Helsingius]

I was upgrading from 14.3-r7 to 14.4, but after the
freebsd-update -r 14.4-RELEASE upgrade,
the reboot fails with
"ZFS: unsupported feature: com.klarasystems: vdev_zaps_v2"
without loading the kernel.

Any idea what that feature is, and how to recover?

Julf

[Daniel Tameling]

Google suggests that your bootloader doesn't support the features of the root partition. Did you perhaps do a "zfs upgrade"? You need to boot from external medium and update the bootloader.
Depending on whether you use UEFI or Bios the steps differ.

Best regards,
Daniel

[Johan Helsingius]

On 30/04/2026 9:46 pm, Daniel Tameling wrote:
> Google suggests that your bootloader doesn't support the features of the root partition. Did you perhaps do a "zfs upgrade"? You need to boot from external medium and update the bootloader.
> Depending on whether you use UEFI or Bios the steps differ.

Thanks - yes, I managed to solve the issue. Booted up on an installer
USB stick, mounted the zfs filesystem, and did an update/upgrade.

Julf

[Einar Indridason]

Is there a way to check a running 14.4 system (upgraded from 14.3) if that ZFS filesystem needs to run a "zfs upgrade" ?  Is there some ... "zfs show-needs-update"

Thanks in advance,

--

EinarI

 

[Matthew Seaman]

On 01/05/2026 13:15, Einar Indridason wrote:
> Is there a way to check a running 14.4 system (upgraded from 14.3) if that
> ZFS filesystem needs to run a "zfs upgrade" ? Is there some ... "zfs
> show-needs-update"
>
> Thanks in advance,

Remember that updates can be applied at both zpool and zfs levels.

`zpool upgrade` will show you if there are upgrades to apply to your
zpools. Then:

`zpool upgrade -a`

or

`zpool upgrade zpoolname`

will actually apply upgrades, either to all pools or to the named pool.

Similarly:

`zfs upgrade`

will show you if there are any updates to apply at the ZFS level, and then:

`zfs upgrade -a`

will apply upgrades to all ZFSes. See `zfs-upgrade(8)` for how to
specify updating selected ZFSes.

Be sure to update boot blocks / EFI as well as updating the zpool, or
you may be left with an unbootable system.

Cheers,

Matthew

[Daniel Tameling]

On Fri, May 01, 2026 at 12:15:49PM +0000, Einar Indridason wrote:
>
> Is there a way to check a running 14.4 system (upgraded from 14.3) if that
> ZFS filesystem needs to run a "zfs upgrade" ? Is there some ... "zfs
> show-needs-update"
>
> Thanks in advance,
> --
> EinarI

zfs upgrade only enables new features that weren't supported before. If you don't want to use these features, there is no benefit in upgrading. Given that the worst case scenario is that the system won't boot afterwards, I upgrade my pools only very rarely.

Best regards,
Daniel