Description

Upon adding a Navigation Block while directly editing a Template Part (eg Appearance → Template Parts), clicking "Add all pages" will produce the error Error loading block: Invalid parameter(s): post_id

Note that the error does not appear directly in the full Site Editor, even when the Navigation Block is added to a Template Part within that context.

Step-by-step reproduction instructions

1. Go to Appearance → Template Parts with a FSE-enabled theme active
2. Create a new Template Part (or edit existing)
3. Add a Navigation block (either horizontal or vertical)
4. Click "Add all pages"
5. Note the error Error loading block: Invalid parameter(s): post_id

Expected behaviour

All pages added

Actual behaviour

Error

Screenshots or screen recording (optional)

Code snippet (optional)

The error happens in this REST API request:

/wp-json/wp/v2/block-renderer/core/page-list?context=edit&post_id=q%2F%2Ftemplate-part-5&_locale=user

That post_id looks fishy indeed. It's omitted in the Site Editor context.

WordPress information

• WordPress version: 5.6.2
• Gutenberg version: 10.0.1
• Are all plugins except Gutenberg deactivated? Yes
• Are you using a default theme (e.g. Twenty Twenty-One)? No

Device information

• Device: Desktop
• Operating system: macOS 11.2.1
• Browser: Chrome 88