It seems that Apple has once more made it necessary to explicitly state the MySQL default socket. As stated in this post Mac, WordPress: “Error establishing a database connection” you should edit the mysql.default_socket = line in your php.ini file to read mysql.default_socket = /tmp/mysql.sock . 

If you don’t know where to look it’s to be found in an invisible folder at the root of your hard drive called “etc”. To get there go to the menu bar when in the Finder: Go -> Go to Folder… or use this shortcut: [Apple]+[Shift]+G ) then type: /etc .

I’d recommend the excellent (and free) TextWranger to edit the file – as it makes it a breeze by automatically authorizing your changes with a prompt for you admin password when needed.

The change is easy – find the line that reads mysql.default_socket = then add /tmp/mysql.sock to the end.

The line should now read  mysql.default_socket = /tmp/mysql.sock

Save the file the restart your Apache webserver by going the System Preferences and stopping, then starting again Web Sharing (found in the Sharing pane).

What’s this about?

Well I tend to use open Safari windows/tabs to help keep me focused on foreground tasks while minimising backround/interesting/to-do articles etc. Occasionally I forget to restore all my windows after restarting Safari for a quick session (usually whilst preparing for shutdown/restart/software update).

Next time you try to restore all your windows and don’t get what you expected – remind yourself this is why that extra Time Machine disk was such a useful investment.

Hope this helps.