Title: WordPress 7 custom HTML broken
Last modified: June 16, 2026

---

# WordPress 7 custom HTML broken

 *  [Eric](https://wordpress.org/support/users/zarglu/)
 * (@zarglu)
 * [3 days, 13 hours ago](https://wordpress.org/support/topic/wordpress-7-custom-html-broken/)
 * Since updating to from WordPress 6.9 to 7, custom HTML blocks display a gray 
   box in the editor with 
   _“This content is blocked. Contact the site owner to 
   fix the issue.”looking at the consoleFraming ‘blob:[https://website/a8a38226-fe28-49c9-8a6c-68e1dd5780e4&#8217](https://website/a8a38226-fe28-49c9-8a6c-68e1dd5780e4&#8217);
   violates the following Content Security Policy directive: “default-src ‘self’
   https: data:”. The request has been blocked. Note that ‘frame-src’ was not explicitly
   set, so ‘default-src’ is used as a fallback.
 * block-editor.min.js?ver=93c3566b7f24c15b7e17:76 Uncaught TypeError: Cannot destructure
   property ‘documentElement’ of ‘z’ as it is null.
   at HTMLIFrameElement.j (block-
   editor.min.js?ver=93c3566b7f24c15b7e17:76:960)there are also warnings leading
   to[https://developer.wordpress.org/block-editor/reference-guides/block-api/block-api-versions/block-migration-for-iframe-editor-compatibility/](https://developer.wordpress.org/block-editor/reference-guides/block-api/block-api-versions/block-migration-for-iframe-editor-compatibility/)
   but what this means is above my paygrade

Viewing 1 replies (of 1 total)

 *  [Zartab Farooquee](https://wordpress.org/support/users/zartabwp/)
 * (@zartabwp)
 * [3 days, 5 hours ago](https://wordpress.org/support/topic/wordpress-7-custom-html-broken/#post-18940439)
 * The error suggests that your site’s Content Security Policy (CSP) is blocking
   the iframe used by the block editor. Since this started after the update, I’d
   check any security headers added by your host, security plugin, CDN, or server
   configuration. Temporarily disabling custom CSP rules may help confirm whether
   that’s the cause.

Viewing 1 replies (of 1 total)

You must be [logged in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fwordpress-7-custom-html-broken%2F%3Foutput_format%3Dmd&locale=en_US)
to reply to this topic.

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 1 reply
 * 2 participants
 * Last reply from: [Zartab Farooquee](https://wordpress.org/support/users/zartabwp/)
 * Last activity: [3 days, 5 hours ago](https://wordpress.org/support/topic/wordpress-7-custom-html-broken/#post-18940439)
 * Status: not resolved

## Topics

### Topics with no replies

### Non-support topics

### Resolved topics

### Unresolved topics

### All topics