Now that wheezy is obsolete, I am considering to upgrade some running servers from wheezy to jessie. The servers are in a multi-server setup with ispconfig 18.104.22.168p8 I would like to keep the currently installed config files for all (dovecot/postfix/apache etc) as they have been heavily customized. This means that services cannot be reconfigured by ispconfig for the time being. Are there any issues to be aware of ? Have you done it ?