db configuration <=> config
config is a shortcut for the configuration database, all other database need to be initiated by 'db database_name'
you can see all possibilities when you press the tab key (autocompletion)
which configs are missing, can you tell us, please do a state of your configuration before and after a post-upgrade/reboot
config show imaps
config show qpsmtpd
the event post-upgrade/reboot is the reconfiguration event, when something goes wrong, you can invoque it to reconfigure in a workable state your server, so all should work after