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Opened 12 days ago

Last modified 4 days ago

#54243 new defect (bug)

Inlined block styles that involve external assets (images/fonts) and relative URL's not working as expected

Reported by: cdyerkes Owned by:
Milestone: 5.8.2 Priority: normal
Severity: normal Version: 5.8.1
Component: Editor Keywords: has-patch needs-testing has-testing-info
Focuses: javascript, css Cc:


When using the tool npx @wordpress/create-block to create a custom block that references assets like images or fonts within scss files used in the build process (that generate style-index.css referenced in block.json that is rendered on the front and backend), the assets are inlined on the front-end with relative URL's which results in a 404 not found error for the referenced asset, rather than a direct url to the file using the plugin's filepath.

The problem still occurs for me using default WordPress themes and no other plugins aside from the custom block created following the @wordpress/create-block official tutorial https://developer.wordpress.org/block-editor/handbook/tutorials/create-block/.

Steps to reproduce:

  1. In a local dev environment (like Local), create a block: npx @wordpress/create-block wp-test-block in the plugins directory.
  2. Copy any external asset you want (like an image) into the block plugin's src directory.
  3. In the file located here src/style.scss add some lines to the prebuilt block CSS class that references the image or other asset you copied into the src directory like this (and save it):
.wp-block-wp-test-block {
    background-color: #21759b;
    color: #fff;
    padding: 2px;
    background-image: url(image-asset.png);
    background-repeat: repeat;
  1. Run npm run build on the block folder to run the build process and then activate the plugin in your local environment within the WP Dashboard.
  2. Go to a page in your local site and add your new block and update the page.
  3. View the page on the front-end and open your dev tools. You will see an error in the console marking the image asset as 404 not found.
  4. Inspect the page's HTML code in the inspector and you will see the block's CSS was inlined in the page like so:
<style id='wp-block-wp-test-block-style-inline-css'>

The background-image: url(image-asset.png); has been inlined using a relative URL that would be equivalent to https://localhost.site/sample-page/images/image-asset.f0104819.png.

What I would expect to happen is for the image asset to use the plugin URL automatically in the build process so the 404 error does not happen. It should have been:

<style id='wp-block-wp-test-block-style-inline-css'>

Or allow us to load a stylesheet (like a <link rel="stylesheet" href="https://domain.com/wp-content/plugins/wp-test-block/build/style.css"> with the proper plugin filepaths via block.json used in the front-end rather than have to use a PHP function to enqueue block assets.

This is my first trac bug submission, so apologies if something isn't clear or correct.

Attachments (1)

wp-bug-screenshot.png (1.2 MB) - added by cdyerkes 12 days ago.
Shows the errors on my local dev site I have been using.

Download all attachments as: .zip

Change History (8)

12 days ago

Shows the errors on my local dev site I have been using.

#1 @gziolo
12 days ago

I can confirm the issue. @aristath, how should we tackle this issue? Any takes on that?

This ticket was mentioned in PR #1752 on WordPress/wordpress-develop by aristath.

11 days ago

  • Keywords has-patch added

When styles get inlined, relative URLs break.
The problem is that URLs inside CSS files are relative to the stylesheet's path, and when styles get inlined that relation is lost.
This PR fixes the issue by finding relative URLs which then get modified to be relative to the site's root.

Trac ticket: https://core.trac.wordpress.org/ticket/54243

#3 @aristath
11 days ago

Added a patch that fixes the issue for relative URLs. The patch also has a PR in Gutenberg to backport the changes there as well: https://github.com/WordPress/gutenberg/pull/35538

Last edited 11 days ago by aristath (previous) (diff)

#4 @SergeyBiryukov
11 days ago

  • Milestone changed from Awaiting Review to 5.8.2

This ticket was mentioned in Slack in #core-test by hellofromtonya. View the logs.

11 days ago

This ticket was mentioned in Slack in #core-test by boniu91. View the logs.

4 days ago

#7 @Boniu91
4 days ago

  • Keywords needs-testing has-testing-info added
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