As a follow up here are some of the other JS errors that are getting triggered on the site. Seems like there is a bad JS library in 3.4.2 somewhere:
Uncaught TypeError: Cannot call method 'appendChild' of undefined assets.pinterest.com/js/pinit.js:22
Uncaught SyntaxError: Unexpected token } events-manager.js:615
Uncaught SyntaxError: Unexpected end of input bootstrap.min.js:7
Uncaught SyntaxError: Unexpected identifier jquery.flexslider-min.js:37
Uncaught TypeError: Object [object Object] has no method 'flexslider'
Refused to display document because display forbidden by X-Frame-Options.
I am using the Pinterest JS for sharing, Events Manager plugin, Twitter Bootstrap and Flexslider. These were all working perfectly up until the upgrade.
Just to clarify, I have disabled all plugins and changed the theme to Twenty Eleven and still having issues. Also, I have individually removed the other libraries in my theme and made sure it's not one of theme causing issues.