Comment 3 for bug 1246732

And just for the record: the reason why the default configuration doesn't work, is that the most recent Ubuntu versions ship with Apache 2.4 and it new authorization model. Even though mod_access_compat is enabled, the Order/Allow directives don't work, because the base Apache configuration in Ubuntu uses Require. Obviously one cannot override the new directives with the old ones, despite the compatibility module.
Workaround: comment out the <Directory /> stanza in /etc/apache2/apache2.conf.