MC4WP plugin prevents iframe editor from loading

[mikeybinns]

WordPress is implementing a new editor style for the WP admin which uses an iframe instead of embedding directly in the page.
https://make.wordpress.org/core/2025/11/12/preparing-the-post-editor-for-full-iframe-integration/

For some reason, this plugin prevents the iframe editor from loading.

Steps to recreate:

1. Create a fresh WP site (this can be done easily here: https://playground.wordpress.net/)
2. Open a post or page in the editor
3. inspect the markup, note there's an iframe with the name editor-canvas which the content is loaded in
4. Install the MC4WP plugin
5. Go back to the same page and check the markup again. See that the iframe for editor-canvas is gone.

I'm not sure why there's a conflict here because you don't export any blocks I can see, but it causes issues when trying to migrate blocks to be iframe compatible, and may cause larger issues on the release of WP 7.

[dannyvankooten]

Thanks for reporting this @mikeybinns - I'll dig into it asap.

[dannyvankooten]

We just had to specify the apiVersion in our call to registerBlockType @mikeybinns - thanks again for bringing this to our attention!

We'll push out an official update on Monday morning, so that most sites should have the update notification just in time before WP 6.9 is officially released.