freebsd stable - Dec 2014 - zpool upgrade - Assertion failed: ... libzfs/common/libzfs_config.c, line 250

Upgraded a fairly recent 10-STABLE to yesterday's version on two hosts
(amd64). Upgrade went fine, things work, but checking for ZFS pool
upgrades on one host fails, while the other is fine:


# zpool upgrade
This system supports ZFS pool feature flags.

All pools are formatted using feature flags.


Some supported features are not enabled on the following pools. Once a
feature is enabled the pool may become incompatible with software
that does not support the feature. See zpool-features(7) for details.

POOL  FEATURE
---------------
big
       large_blocks
Assertion failed: (nvlist_lookup_nvlist(config, "feature_stats", 
&features) == 0), file 
/usr/src/cddl/lib/libzfs/../../../cddl/contrib/opensolaris/lib/libzfs/common/libzfs_config.c,
line 250.
Abort trap


   Mark

P.S. Seems this was due to one external (removable) disk (with its
own pool) not being connected to the host. After making it available,
the 'zpool upgrade' command completed normally, listing all pools.

   Mark

> Upgraded a fairly recent 10-STABLE to yesterday's version on two hosts
> (amd64). Upgrade went fine, things work, but checking for ZFS pool
> upgrades on one host fails, while the other is fine:
> 
> # zpool upgrade
> This system supports ZFS pool feature flags.
> 
> All pools are formatted using feature flags.
> 
> 
> Some supported features are not enabled on the following pools. Once a
> feature is enabled the pool may become incompatible with software
> that does not support the feature. See zpool-features(7) for details.
> 
> POOL  FEATURE
> ---------------
> big
>       large_blocks
> Assertion failed: (nvlist_lookup_nvlist(config, "feature_stats",
> &features) == 0), file
>
/usr/src/cddl/lib/libzfs/../../../cddl/contrib/opensolaris/lib/libzfs/common/libzfs_config.c,
> line 250.
> Abort trap