Description

In #68819, the save function was updated to not break blocks when deleting height, saving, and reloading the browser.

This appears to have affected backwards compatibility in certain contexts. For example, one pattern in Twenty Twenty-Five is affected and will result in a browser console error when you open the Patterns screen in the site editor.

Step-by-step reproduction instructions

This issue can be reproduced in two ways.

Insert a spacer inside the Row/Stack block

• Update your local WordPress version to 6.7 and disable the Gutenberg plugin beforehand.
• Insert a Row or Stack block. Insert a Spacer block inside it.
• Change "Width" to "Fill".
• Save the post.
• Activate the Gutenberg plugin.
• Open the post.
• Verify that the Spacer block is broken.

Issue in the Twenty Twenty-Five theme

• Insert the "Hero, overlapped book cover with links" pattern into the content.
• Verify that the spacer block breaks.

logger.js:17 Block validation: Block validation failed for `core/spacer` (
{name: 'core/spacer', icon: {…}, keywords: Array(0), attributes: {…}, providesContext: {…}, …}
).

Content generated by `save` function:

<div style="margin-top:var(--wp--preset--spacing--20);margin-bottom:var(--wp--preset--spacing--20);height:100px" aria-hidden="true" class="wp-block-spacer"></div>

Content retrieved from post body:

<div style="margin-top:var(--wp--preset--spacing--20);margin-bottom:var(--wp--preset--spacing--20)" aria-hidden="true" class="wp-block-spacer"></div>

Screenshots, screen recording, code snippet

No response

Environment info

No response

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure