failing beadm

All of a sudden I was unable to create a new environment.

hajma@briza:~$ pfexec beadm create test
Unable to create test.
Doesn't exist.

Huh. After a bit of googling a learned about the BE_PRINT_ERR variable and that helped me to find the culprit:

hajma@briza:~$ BE_PRINT_ERR=true pfexec beadm create test
get_mountpoint_from_vfstab: failed to open vfstab (/export/testzone/root/etc/vfstab)
_update_vfstab: failed to open vfstab (/tmp/.be.TTayGg/etc/vfstab): No such file or directory
be_copy_zones: failed to update new BE's vfstab (zbe-1)
be_copy: failed to process zones
be_copy: destroying partially created boot environment
Unable to create test.
Doesn't exist.

It looks like the testzone was to blame. Since I did not have anything of a value in that zone, I just deleted it and everything started working again.