Solaris Zone down

I made a minor configuration change to a Solaris zone and rebooted the zone.

On the way back up it hung with an error message about booting.

I entered zoneadm list -cv with the following results

root@server01 # zoneadm list -cv

ID NAME STATUS PATH BRAND IP
0 global running / native shared
1 licence3-zone running /export/home/zones/licence3-zone native shared
2 licence2-zone running /export/home/zones/licence2-zone native shared
5 licence-zone running /export/home/zones/licence-zone native shared
7 licence1-zone running /export/home/zones/licence1-zone native shared
21 la-zone running /export/home/zones/la-zone native shared
23 build-machine down /export/home/zones/build-machine native shared
24 build-2 running /export/home/zones/build-2 native shared
- build-1 installed /export/home/zones/build-1 native shared
root@server01#
Its state was shown as down!

I entered
zoneadm -z build-machine halt
but it failed with a message saying the zone's /tmp directory couldn't be unmounted.

Entering
zoneadm -z build-machine reboot
failed with a similar message.

Entering
zoneadm -z build-machine boot
was the same.

So I traversed the zone's filesystem from the global zone. I'd downloaded some files to the zone's /tmp directory. I deleted the entire contents and entered
zoneadm list -cv
Its state was still shown as down!
I entered zoneadm -z build-macxhine halt, which returned without error. A zoneadm list -cv showed some good news.

root@server01 # zoneadm -z build-machine halt
root@server01 # zoneadm list -cv
ID NAME STATUS PATH BRAND IP
0 global running / native shared
1 licence3-zone running /export/home/zones/licence3-zone native shared
2 licence2-zone running /export/home/zones/licence2-zone native shared
5 licence-zone running /export/home/zones/licence-zone native shared
7 licence1-zone running /export/home/zones/licence1-zone native shared
21 la-zone running /export/home/zones/la-zone native shared
24 build-2 running /export/home/zones/build-2 native shared
- build-machine installed /export/home/zones/build-machine native shared
- build-1 installed /export/home/zones/build-1 native shared
root@server01 #

And it booted successfully. Huzzah!

Well, that's that!