Error when editing custom post type with non-Latin slug in Gutenberg: "You attempted to edit an item that doesn't exist."

[mafiayemakhfi]

Description

When attempting to edit a custom post type with a Persian slug in the Gutenberg editor, I encounter the error message:

"You attempted to edit an item that doesn't exist. Perhaps it was deleted?"

The post is still accessible via its URL, and no data appears to be lost. This issue seems to be related to the handling of slugs containing non-Latin characters in the Gutenberg editor.

Step-by-step reproduction instructions

1. Create a custom post type (CPT) with a Persian slug.
2. Example: my_custom_post_type with a slug like ویدیو (or any Persian characters).
3. Permalink structure should be /%postname%/ .
4. Publish a post in that CPT.
5. Attempt to edit the post using the Gutenberg editor by navigating to the post editing screen.
6. The error message "You attempted to edit an item that doesn't exist" appears.

$video_labels = array(
            'name'                => _x('Videos', 'Post Type General Name', 'test'),
            'singular_name'       => _x('Video', 'Post Type Singular Name', 'test'),
            'menu_name'           => __('Videos', 'test'),
            'parent_item_colon'   => __('Video :', 'test'),
            'all_items'           => __('All Videos', 'test'),
            'view_item'           => __('View Video', 'test'),
            'add_new_item'        => __('Add Video', 'test'),
            'add_new'             => __('Add Video', 'test'),
            'edit_item'           => __('Edit Video', 'test'),
            'update_item'         => __('Update Video', 'test'),
            'search_items'        => __('Search Video', 'test'),
            'not_found'           => __('Video Not Found', 'test'),
            'not_found_in_trash'  => __('No Video Found In Trash', 'test'),
        );

        // Register Video Post Type
        register_post_type(
            'video',
            array(
                'labels'        => $video_labels,
                'public'        => true,
                'supports'      => array ( 'comments', 'title', 'editor', 'thumbnail','revisions' ),
                'has_archive'   => true,
                'show_in_rest'  => true,
                'rewrite'       => array('slug' => 'ویدیو'),
                'taxonomies'    => array('category', 'post_tag', 'artist_cat'),
                'menu_icon'     => 'dashicons-video-alt3',
                'menu_position' => 5
            )
        );

Screenshots, screen recording, code snippet

No response

Environment info

WP Version	6.7.1
Site Language	en_US
User Language	en_US
Timezone	+00:00
Home URL	http://localhost
Site URL	http://localhost
Permalink structure	/%postname%/
Is this site using HTTPS?	No
Is this a multisite?	No
Can anyone register on this site?	No
Is this site discouraging search engines?	No
Default comment status	Open
Environment type	production
User count	1
Communication with WordPress.org	WordPress.org is reachab

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

[SainathPoojary]

Hey @mafiayemakhfi,

I confirm that I was able to reproduce the bug in the environment described below. I used the code snippet provided in the description to create a custom post type (CPT).

Environment

• WordPress: 6.7.1
• PHP: 8.1.29
• Server: nginx/1.16.0
• Database: mysqli (Server: 8.0.16 / Client: mysqlnd 8.1.29)
• Browser: Chrome 131.0.0.0
• OS: macOS
• Theme: Twenty Twenty-Five 1.0
• MU Plugins: None activated
• Plugins: Test Plugin

2024-11-28.10-11-34.mp4

[himanshupathak95]

Hey @mafiayemakhfi, Thanks for bringing this up.

I was able to reproduce the issue following the above-mentioned steps. Here are the details -

Environment

• WordPress: 6.8-alpha-59366
• PHP: 8.2.25
• Server: Apache/2.4.62 (Debian)
• Database: mysqli (Server: 11.4.3-MariaDB-ubu2404 / Client: mysqlnd 8.2.25)
• Browser: Chrome 131.0.0.0
• OS: macOS

Screencast -

Screen.Recording.2024-11-28.at.11.02.12.mov

[Juzar10]

The issue occurs because of the encoding error for the api-fetch module, which the editor is getting called for.

PR: #67780

Above PR fixes the issue by correcting the encoding for the header where the link is getting used which might have the Persian slug.

[t-hamano]

The same issue was reported in #68793. After my investigation, it seems that this issue was caused by #63430.

[Mamaduka]

As noted in #67780, the problem comes from the apiFetch package. It became more evident after #63430, which disabled parsing for the request.

[Mamaduka]

I discussed this with @TimothyBJacobs, and this is probably a REST API or Rewrites core component issue.

Here's what is happening:

• When a resource data is preloaded for editors, apiFetch middleware will try to reconstruct Response from a JSON object.
• The "Link" header contains a non-Latin post-type rewrite slug, and the Response web API throws an error since it only works with Latin/ISO-8859-1 chars.
• The resource request fails, and the editor assumes it's missing from DB.

Possible solutions:

• Encode CPT rewrite slugs before the REST Server returns data. Note that non-Latin post slugs are already encoded.
• Try encoding Link headers in preloading middleware - Fix: Prevent Errors in Header Processing and Encode URLs Properly #67780.

Screenshot

Currently, preloaded headers look like this: