If postfix jail is enabled at time of upgrade, upgrading fails because when fail2ban attempts to restart after upgrade, it can't find the postfix log file now set in paths-delian.conf.
Also occurs if dovecot jail is enabled, because by default, dovecot jail looks in the same log file as postfix jail.
This may also be related to the following bugs.
#1482899
#1669512
#1645693
If postfix jail is enabled at time of upgrade, upgrading fails because when fail2ban attempts to restart after upgrade, it can't find the postfix log file now set in paths-delian.conf.
Also occurs if dovecot jail is enabled, because by default, dovecot jail looks in the same log file as postfix jail.