This is because you forgot to back up your httpd.conf… – easily fixed:
First, back up the current httpd.conf
:
(you’ll need to be root, so either su or run the following commands with sudo)
cd /etc/apache2
mv httpd.conf httpd.conf.preUpgrade
mv httpd.conf~previous httpd.conf
and then restart apache:
apachectl restart
now your local vhosts will work again.