Apache localhost 403 error with Yosemite

You do NOT want to open up the entirety of your hard drive to the web server process. In fact, lines 215-217 of httpd.conf say:

# Deny access to the entirety of your server's filesystem. You must
# explicitly permit access to web content directories in other
# <Directory> blocks below.

Apache 2.4 (OSX 10.10 Yosemite) has a different structure from Apache 2.2 (OSX 10.9) for the Directory directive in Module mod_authz_core.

EDIT: If you are setting up Apache from the START, please follow this instruction set to setup apache and php on OSX 10.10 Yosemite.

Assuming you have mod_userdir.so enabled already, your problem is within your user .conf file (/etc/apache2/users/username.conf), edit (or add) the following.

Apache 2.2:

<Directory "/Users/jnovack/Sites/">
  Options Indexes MultiViews
  AllowOverride All
  # OSX 10.9 / Apache 2.2
  Order from deny, allow
</Directory>

Apache 2.4

<Directory "/Users/jnovack/Sites/">
  Options Indexes MultiViews
  AllowOverride All
  # OSX 10.10 / Apache 2.4
  Require all granted
</Directory>