I'm a french user of Virtulamin and Webmin. I had a serious problem yesterday that we figured out with a friend. I'm creating this post to share the solution and maybe warm the virtualmin creators. And sorry in advance for my english ;).
I've installed Virtualmin from the install.sh script (http://www.virtualmin.com/download.html) on my ubuntu 12.04 server because it's faster to configure typical web server with the more classics features : apache, mysql, php5, bind, ftp, spamassassin, etc...
Once I've did that, i've created my vhosts to match my domains names with my directories. No problems here.
Then, I've downloaded the latest wordpress archive from the official website and uploaded it to the target folder on my server.
And here was the problem, my web server didn't have any problems to interpret the html but was not able to make the same with php. The only error message that i've had was an "internal server error"...
So it was impossible to me to launch the wp-config.php file to start configuring wordpress.
Here is the solution step by step :
1- I've red the website error log (located at var/log/virtualmin/youwebsite) and I've found there this error : "Connection reset by peer: mod_fcgid: error reading data from FastCGI server".
2- I've googled this error and i've found this post, reporting the exact same problem than me : http://www.virtualmin.com/node/25539
3- The fourth step says : "switch back to apache mod_php mode and then back to FCGId mode" but nothing more.
4- After few hours of search, I went to Virtualmin -> Server Configuration -> Website Options and I've changed the FCGId mode to the mod_php one. After clicking on the Apply button, I've changed again the mode to go back to the FCGId one.
5- Strangely, my server interprets my php code after this change but I've got a database connection error even if I thought to add the correct parameters in the wp-config.php file.
6- Here is a specific behavior of webmin : when you're adding a vhost in the webmin control panel, he's creating itself a database with the exact same name of the vhost, and also a database user and password.
7- After few hours of search again, I've found where you can find this informations in the webmin control panel. Select your vhost in the combo list, click on "Edit Databases", click ont the "Passwords" tab and then click on "Show..". A popup will give you the database user (which is also the same name than the vhost) and password.
8- Enter these informations in the wp-config.php and that's it !! The database connection error will disappear and you will be able to start the wordpress configuration.