I've had to remind myself this every time I upgrade the distributions on my Workstations and notebook. Being used to Apache 1.x, I tend to go back to editing the old way - changing httpd.conf or apache2.conf for vhost configuration. On Apache 2 there are separate files for this (under sites-available) which is clean and much more trouble free.

But one thing you might overlook for a moment while upgrading distributions, is about mod_rewrite. You see that the module is enabled, you see the rewrite.load file under modules-enabled directory in the apache conf directory (which is usually under /etc/apache2 for standard installs). But the mod_rewrite still doesn't work.

Trivial as it is (something that might not even deserve this lengthy note about it), it might baffle you for a bit unless you figure that the AllowOverride all directive that you wrongly placed on apache2.conf should have been on sites-available/default.