Edited Reusable Block Bug Breaks Post/Page and Calypso - Site - Posts/Pages (no posts/pages appear)

[scosgro]

I'm not 100% sure about how the user whose site this bug was affecting reached this conclusion, but I've found a way to replicate the bug (or something very much like it).

Steps to reproduce

1. Starting on a WordPress.com Simple Site
2. Create a post. Add a Paragraph Block with some text in it.
3. Make that block a Reusable Block. Give it a name (just to distinguish it). Save. Publish the post. Open the post in a new tab.
4. Create a new post.
5. Click to add a block, go to Reusable Blocks - Manage All Reusable Blocks. At the moment, you need to open this in a new tab. Opening it in the same window will fail. See Manage Reusable Blocks Link Fails in Calypso. New Tab Opens in Calypso-ify.  #38928 (discovered while investigating this bug).
6. Hover over the block you've created, and click Classic Editor.
7. When editing the block in the classic editor, make the block refer to itself by adding:

<!-- wp:block {"ref":BLOCK-NUMBER-HERE} /-->

8. The Block Number can be found in the URL.
9. Update.
10. Refresh the post this reusable block appears on. The post will be completely broken.
11. The post will also fail to appear in Calypso under Site - Posts. It will still appear in WP-Admin.
12. For the user's site, all posts disappeared from Calypso. I haven't been able to replicate this, though it does break Calypso in some way (step 11).

What I expected

I'm not totally sure the workflow the user went through to get to this point. They didn't seem like they were too sure either. There has to be an easier way to do it, but I haven't found it. This was only the way I could replicate it based on what I saw on their site.

Expected the reusable block to not break the post/Calypso.

What happened instead

The Block breaks the post/Calypso once updated in this way.

Browser / OS version

All.

Screenshot / Video

.gif is a bit long, but shows the full workflow, including the aftermath.

https://cloudup.com/co-14A0XSOg

Context / Source

#reallife #painpoint.

#user-report

[AtrumGeost]

Got a similar case here 2649686-zen

[scosgro]

Another one in 3124526-hc

[desnum]

Another similar case in 18426919-hc:
No pages show in Calypso, though they're there in WP Admin.

[kriskarkoski]

@mrfoxtalbot I'm not following. Was that meant for another issue perhaps?

[mrfoxtalbot]

I am sorry, @kriskarkoski! I meant to add this comment on a different issue, please disregard my comment.

[kriskarkoski]

Confirmed this issue is still present and self-referencing also makes the Reusable Blocks option disappear when adding blocks on a new post and saving to fail on the post if you open the editor, edit the reusable block to self-reference, and then try to save a post with it present.

I also tested on a core install and was able to reproduce issues there, specifically fatal errors due to timeouts in /wp-includes/class-wp-block-parser.php on line 417 and /wp-includes/class-wp-block-parser.php on line 417.

@scosgro Do you want to open the issue on https://github.com/WordPress/gutenberg/issues?

[scosgro]

Posted here: WordPress/gutenberg#21117

[katiebethbrown]

Another report here:
3290676-zd-woothemes

[cathymcbride]

This is a duplicate of WordPress/gutenberg#18704. I'm going to leave it open to make it easier to find.

[kriskarkoski]

Another case in 3655674-zen

[synora]

WordPress/gutenberg#18704 has been closed.
I'll close this one in favor of #49007