Child Themes: template-parts links should include the child theme slug and not the parent theme slug.

[matiasbenedetto]

When a template part is linked from a pattern it should have the theme key and it should contain the theme slug of the child theme.

Example:

<!-- wp:template-part {"slug":"header","theme":"childthemeslug"} /-->

Currently, when we export a child theme we use the parent theme slug and that avoids the template part to be loaded as expected in the editor causing the error: Template part has been deleted or is unavailable.

More info in this Gutenberg issue: WordPress/gutenberg#44243 particularly in WordPress/gutenberg#44243 (comment)

[miksansegundo]

Just noting that the same error Template part has been deleted or is unavailable reported in this issue also happens on themes that are exported with the "Clone" option.

Updating the value of the theme key in the template-part to use the cloned or current theme slug didn't help in that case.

[matiasbenedetto]

Updating the value of the theme key in the template-part to use the cloned or current theme slug didn't help in that case.

@miksansegundo I'm interested in this you mentioned. Did you try adding "theme":"yourthemeslug" ?

Could you attach the zip file obtained to help to debug?

[miksansegundo]

@matiasbenedetto here are the steps I followed:

• Install and activate blank-canvas-3 theme
• From the editor add a Front Page template
  • Add a Header template part
  • Edit the template part
• Export the theme using CBT plugin with Clone option using the name Lodestar. See theme test.zip

Notice that CBT plugin exported a front-page pattern with the header template part using the value lodestar-3-wpcom in the theme attribute, which was unexpected:
<!-- wp:template-part {"slug":"header","theme":"lodestar-3-wpcom","tagName":"header"} /-->.

When I upload and activate the theme on a Jurassic site, I got the same error as in this issue. See screenshot:

After updating the theme attribute to be "theme":"lodestar" or "theme":"blank-canvas-3" the error persisted.