Failed to execute 'postMessage' on 'DO

Question

This is the error message that I get:

Failed to execute 'postMessage' on 'DOMWindow': The target origin provided
('https://www.youtube.com') does not match the recipient window's origin 
('http://localhost:9000').

I've seen other similar problems where the target origin is http://www.youtube.com and the recipient origin is https://www.youtube.com, but none like mine where the target is https://www.youtube.com and the origin is http://localhost:9000.

1. I don't get the problem. What is the problem?
2. How can I fix it?

Answer 1

This exact error was related to a content block by Youtube when "playbacked on certain sites or applications". More specifically by WMG (Warner Music Group).

The error message did however suggest that a https iframe import to a http site was the issue, which it wasn't in this case.

Answer 2

Setting this seems to fix it:

  this$1.player = new YouTube.Player(this$1.elementId, {
    videoId: videoId,
    host: 'https://www.youtube.com',

Answer 3

Remove DNS Prefetch will solve this issue.

If you're using WordPress, add this line in your theme's functions.php

remove_action( 'wp_head', 'wp_resource_hints', 2 );

Answer 4

I had this same problem and it turns out it was because I had the Chrome extension "HTTPS Everywhere" running. Disabling the extension solved my problem.