I report the same issue after an unattended upgrade of last night, the postfix service was in state Active (Excited). Restarting with debugging options with
/etc/postfix/master.cf:
smtp inet n - n - - smtpd -v
didn't give additional log entries, only:
postfix/postqueue[2130]: warning: Mail system is down -- accessing queue
directly
I confirm that for me also reinstalling solved it.
Joris.
