Apple is very supportive with the buying public by releasing free upgrades for its operating systems. These upgrades usually go through without a hitch, but your web development environment can be left in tatters. Here's what I had to do to fix things.
In /etc, mv php.ini.default to php.ini To re-enable xdebug support, add this to /etc/php.ini: [xdebug] zend_extension=/usr/lib/php/extensions/no-debug-non-zts-20121212/xdebug.so In php.ini, add /usr/local/lib/php to the include_path To enable php support for mysql sockets, update this setting in php.ini: mysql.default_socket = /tmp/mysql.sock To allow mysql to get your settings: ln -s /usr/local/mysql/my.cnf /etc/ Restart mysqld using the System Settings UI (look in spotlight for mysql). Restart apache using apachectl restart
Note that you will need to do most (or all) of this as sudo.