Failed to execute 'postMessage' on 'DOMWindow': The target origin provided does not match the recipient window's origin ('null')

Question

I have a game in heroku, now I\'m trying to make it work in Facebook canvas, but, while it works in Firefox, in Chrome and IE doesn\'t.

IE shows a warning with a but

Answer 1

In my case I didn't add the http:// prefix. Potentially worth checking.