One of the things that the package configures is a user and group named nagios.
When I took a look into the /etc/group file I noticed that apache was a member of the nagios group but no longer a member of the ispconfig group.
" if [ $retval -eq 0 ]; then compile=1; fi sa-update --nogpg --channel sought.org retval="$?
" if [ $retval -eq 0 ]; then compile=1; fi sa-update --nogpg --channel spamassassin.retval="$?
All appeared well when I went to sleep meaning the servers seemed to all check out when was finished and ready to catch some sleep.
Anyways when I logged on the following day to check all of the sites all was still functional besides a small DNS configuration error I had made with one sub domain which was not a big deal.
The chances for a successful and fully functional upgrade are decreased by a number of 3rd-party packages installed on your current system.
I have had a server running ISPConfig 2.x for quite some time and have been wanting to make the transition to ISPConfig 3.x as soon as I had a chance.
That chance presented itself earlier this weekend and I am glad to say there were no major issues thanks to the amazing how to from Falco at How To Forge.
I can only assume that something about the nagios package accidentally removed apache from the ispconfig group access.
I assume that this could happen with other packages so if You are getting 403 Forbidden errors only when visiting the ISPConfig administration section you should verify that apache is in the ispconfig group.