Table block: CRDT initialization replaces cell content with empty objects

[lancewillett]

Description

When Real-Time Collaboration (RTC) is enabled, table block cell content renders blank in the editor. The CRDT document initialization replaces RichText cell content (strings) with empty {} objects in the block attributes, while originalContent and post_content remain intact.

Preview and front-end rendering are unaffected — only the editor view is broken.

Steps to reproduce

1. Create a post with a core/table block containing data in header and body cells
2. Enable Real-Time Collaboration (RTC) with the HTTP polling provider
3. Save the post
4. Reload the editor

Expected: Table cells show their content
Actual: All table cells render blank (empty textboxes)

Technical analysis

Performed via browser DevTools on a live WordPress.com P2 site running Gutenberg 22.7.0:

Block attributes are corrupted

// Every cell's content is an empty plain object:
tableBlock.attributes.head[0].cells[0].content
// → {} (Object with zero keys, not a RichTextData instance)

tableBlock.attributes.body[0].cells[0].content
// → {} (same)

Normal (non-RTC) table cells store content as strings ("Product", "<a href='...'>Link</a>"). With RTC enabled, the CRDT initialization replaces these with empty {} objects.

originalContent is intact

tableBlock.originalContent
// → '<figure class="wp-block-table"><table><thead><tr><th>Product</th>...'
// All cell data present and correct

Serialization vs rendering divergence

• getEditedPostContent() returns correct HTML with all table data (serializes from originalContent)
• React renders from block attributes (head/body arrays) → blank cells
• isValid: true because validation checks against originalContent, not attributes

The corruption happens at CRDT init time

Even after deleting _crdt_document post meta, the bug reproduces on the very next page load. The CRDT system creates a new document from the parsed blocks, and during that initialization, table cell RichText content is not properly captured.

The issue is specifically with how the CRDT document handles RichText attribute sources (source: 'html') stored as block attributes in the table block. Table cells use source: 'html' attributes (unlike paragraph/heading blocks which use source: 'rich-text' on innerHTML). The CRDT initializer appears to not handle this attribute type correctly.

Workaround

Re-parsing the block from originalContent and updating attributes in the store restores the data:

const reparsed = wp.blocks.parse('<!-- wp:table ... -->' + tableBlock.originalContent + '<!-- /wp:table -->');
wp.data.dispatch('core/block-editor').updateBlockAttributes(tableBlock.clientId, {
  head: reparsed[0].attributes.head,
  body: reparsed[0].attributes.body,
});

This is a temporary in-memory fix — the CRDT re-corrupts on next page load.

Environment

• WordPress.com (Simple sites)
• Gutenberg 22.7.0
• RTC provider: HTTP polling
• Affects: core/table block (likely any block using source: 'html' RichText attributes)

Related

• Reported by multiple users across different WordPress.com P2 sites
• Bug persists after Gutenberg 22.7.0 update (which fixed other RTC/polling issues)

[Sourav61]

Hey @lancewillett I attempted to reproduce this issue using Gutenberg (latest) in a WordPress Playground environment with experiments enabled, but was unable to replicate the behavior.

After creating a table block, saving, and reloading the editor, the cell content remains intact. Inspecting via DevTools shows that attributes.head/body[].cells[].content contains the expected string values (e.g., "Test", "A") rather than empty objects ({}).

This suggests that the issue may depend on a fully functional RTC/CRDT backend (such as the WordPress.com P2 environment with HTTP polling provider), which may not be available or fully simulated in Playground.

Could you confirm if there are any additional configuration steps or environment requirements needed to reproduce this outside of WordPress.com?

[alecgeatches]

I was able to reproduce this locally with Gutenberg trunk and wp-env:

Screen.Recording.2026-03-17.at.11.47.56.AM.mov

1. Create a post with a table:

   npm run wp-env run cli -- wp post create --post_title='Table Test' --post_status='publish' --post_content='<!-- wp:table --><figure class="wp-block-table"><table class="has-fixed-layout"><tbody><tr><td>1</td><td>2</td></tr><tr><td>3</td><td>4</td></tr></tbody></table></figure><!-- /wp:table -->'

2. As user A, load the post in one tab with RTC enabled.

3. As user B, load the same post in a second tab with RTC enabled.

4. See user A's table get cleared out.

[alecgeatches]

This was closed automatically with the fix in #76597, but feel free to comment or reopen if you continue to encounter any related table issues.