Does anyone have any experience they can post here, if there were any issues with your OS upgrade and ispconfig, please post. I plan to use this guide: https://www.rootusers.com/how-to-upgrade-debian-7-wheezy-to-debian-8-jessie/ Obviously taking into the account these Debian 8 upgrade pitfalls: https://www.debian.org/releases/jessie/amd64/release-notes/ch-information.en.html The only one of those that scares me is the "PermitRootLogin without-password" issue.
https://www.howtoforge.com/tutorial/how-to-upgrade-debian-wheezy-to-jessie-stable-release/ afterwards run update.php from the ispconfig-archive and choose reconfigure services. jessie comes with apache 2.4. if you use apache, run the resync-tool to write the new apache-vhosts.
I just migrated to a multi-server setup with two new DNS servers on a cheap cloud hosting service. $15 bucks a month all-you-can-eat bandwidth for 2 small cloud hosted VPS, seemed better than the AWS tier. I installed them as Debian 8 servers and used the prefect server guide and multiserver squeeze guide to mix the proceedures to get the right config. It all worked out better and easier than expected. I really did not have to go hunting for any bugs at all, even applying the DKIM patches and all. It was great! I also migrated one of my servers from Debian 7 to Debian 8 in the process. I just ran the update as you said and resynced; and away it went. It's all working.
