Updating incorrectly indicates it failed
I updated from FreeNAS-9.3-Nightlies-201501100401 to FreeNAS-9.3-Nightlies-201501130401 and got an error message/alert that the update had failed, but it was actually successful based on what is shown in System->Boot and System->Information.
Update failed. Check /data/update.failed for further details.
Sean Fagan's analysis:
So this is a red herring...
What's going on is that we changed the post-upgrade scripts to do the database migration, rather than touch a sentinel file, reboot, have it notice that file and do the migration, and then reboot again. So it saves a reboot.