Core Data: Can't open editor if post type rewrite slug is non-Latin

[t-hamano]

Description

Originally reported in Core: https://core.trac.wordpress.org/ticket/62776

If you register a CPT with a rewrite slug that uses non-latin characters then when you click a back-end link to edit such a post the editor fails to load and displays a message "You attempted to edit an item that doesn't exist. Perhaps it was deleted?".

Does not happen in WordPress 6.6.2, happens in WordPress 6.7+

After checking with git bisect, this issue seems to be related to #63430.

Step-by-step reproduction instructions

• Launch WordPress version 6.6.2.
• Disable the Gutenberg plugin.
• Add the following code somewhere:

  function my_custom_post_type() {
  	$recipe_args = array(
  		'label' => 'Recipes',
  		'public' => true,
  		'rewrite' => array('slug' => 'рецепт'),
  		'show_in_rest' => true,
  	);
  	register_post_type('recipe', $recipe_args);
  }
  add_action('init', 'my_custom_post_type');

• Change the permalink to "Post name".
• Open a new post of the post type "Recipes".
• You should be able to edit correctly.
• Enable the Gutenberg plugin.
• Open a new post of the post type "Recipes".
• You should see the message You attempted to edit an item that doesn't exist. Perhaps it was deleted?.

Screenshots, screen recording, code snippet

15463ef930a8f93124f3e20377b4ef3e.mp4

[t-hamano]

@Mamaduka Do you know anything about this issue? I've been debugging around this and it looks like it's not getting the allowed methods correctly.

[carolinan]

Thank you for bringing this over.

[carolinan]

I was searching for something else and noticed this: #67358

[t-hamano]

Let's close this issue and add #67358 to the project board move forward with #67358.

[Mamaduka]

Thanks for checking the duplicates, @carolinan!

@t-hamano, do you mind sharing your findings in the original issue?