Well then, got a servercrash on my Ubuntu 10.04 while upgrading to 12.04 (Grub lost information about the partition where the /home directory was located, and all Websites were hosted. Fortunately i got 30days of virtualmin backups on the second partition, where i could start some sort of a rescue system, put the backups onto another server, reinstalled the one with debian 7.5, which was the best option, besides Ubuntu 14.04, which i found too new in order to put in production i and rebooted.
i made sure, i would have a FQDN set and executed install.sh which didn't run through the first time, giving me strange errors like "debiantype webmin not found, could not remove", so i ran it a second time. This time it went through and webmin was accessible, as well as the apache webserver too.
So far nothing unresolvable.
Since i couldn't run this commands:
mkdir /root/backups virtualmin backup-domain --dest /root/backups/ --all-domains --all-features --newformat --all-virtualmin
because the partition wasn't recoverable, i had to use my daily backups.
Now the fun part:
virtualmin restore-domain --source /root/backups/virtualmin.tar.gz --all-virtualmin
Didn't work out, wouldn't recognize any of the files available to rebuild the settings of virtualmin.
also this:
virtualmin restore-domain --source /root/backups/ --all-domains --all-features
didn't work at all.
I panicked for a short while and tried to use the Restore function of virtual min.
It did work out for smaller websites, others would hang forever.
Turned out, that the standard settings in the standard plan had disk quota and the standard php settings wouldn't apply as well.
When i restored the sites, i went to the frontend, and got strange error messages. After literally HOURS of checking, trying to use different .htaccess files in order to get php 5.4.x running, it turned out, that suexec had been activated as apache module. Disabling and restarting Apache did the trick.
This i couldn't find anywhere, the solutions all were about downgrading PHP or fumbling around with those .htaccess files, whereas deactivating suexec would have saved me a lot of time.
So, if you are in the same position as i was:
First set php.ini variables to real world values mainly in execution time, max_upload, max_post size and restart apache.
Second check, whether suexec is activated or not, if it is, deactivate it and restart apache.
Third: Check the settings of both virtualmin server AND the serverplans, the latter one to raise the quota, so you can upload your backups.
Then everything should be fine :-) Best