Sorry missed a line in my previous post, just to make it clear that's not the cause of the error:
I'm loading the extension from my old LocalSettings.php like this:
require_once("${IP}/extensions/ConfirmEdit/ConfirmEdit.php");
require_once("${IP}/extensions/ConfirmEdit/ReCaptcha.php"); $wgCaptchaClass = 'ReCaptcha'; $wgReCaptchaPublicKey = 'xxx'; $wgReCaptchaPrivateKey = 'xxx';
Cheers, Adam.