Note to the web server sys admins.

Did you upgrade to Ubuntu 13.10? It’s the latest as of Nov 2013 when writing and if you were on an older Ubuntu version then when you logged in it probably suggested you ran do-release-upgrade.

Did you press Y or I and accept the package maintainers version of the apache.conf file? I think this is where the problem comes in. But as the error only just occurred haven’t had time to research.

Are your websites showing the default page? Something like :

It works!

This is the default web page for this server.

The web server software is running but no content has been added, yet.

When you run a2ensite or a2dissite does it show an error like the one below (except with a different site name of course)?

 ERROR: Site kublermdk does not exist! 

The Fix

You need to rename your /etc/apache2/sites-available/ files to include a .conf extension. 

That is, instead of having the file just called kublermdk you need to call it kublermdk.conf, then you can run  sudo a2enssite kublermdk.conf , restart apache with   sudo service apache2 reload  and it’ll work!

 

Story form

Ubuntu 13.10 Upgrade: When upgrading to the latest 13.10 version of Ubuntu and pressed Y to used the Package maintainers apache.conf file then the Apache sites-available config files need to have a .conf extension.
This requirement wasn’t needed before, so my files were just called the base domain, like kublermdk or greyphoenix, now it needs to be kublermdk.conf and without it Apache doesn’t seem to see your site.
Even if you still have the original symlink into the sites-enabled directory the config still won’t work, most likely the 000-default.conf file will work and instead of showing something awesome your site will show a default site page.