Classic Theme with theme.json attempts to load templates

[CookiesForDevo]

With 6.5 if a classic theme has a theme.json, editing a post/page attempts to load templates resulting in a bevy of php warnings with the $template var being null inside prepare_item_for_response.

Tested with twentynineteen and adding a theme.json with only the version number.

[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "id" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 647
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "theme" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 651
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "content" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 658
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "content" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 662
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "slug" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 666
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "source" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 670
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "origin" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 674
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "type" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 678
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "description" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 682
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "title" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 690
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "wp_id" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 694
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "title" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 698
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "status" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 703
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "wp_id" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 707
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "has_theme_file" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 711
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "type" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 714
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "author" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 719
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "modified" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 727
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "type" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 769
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "author" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 829
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "type" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 769
[03-Apr-2024 13:59:04 UTC] PHP Warning:  Attempt to read property "id" on null in /app/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php on line 746
[03-Apr-2024 13:59:04 UTC] PHP Deprecated:  explode(): Passing null to parameter #2 ($string) of type string is deprecated in /app/wp-includes/block-template-utils.php on line 1076

[audrasjb]

Hello and welcome to WordPress Core Trac, thanks for the ticket

Moving to 6.5.1 for investigation.

[CookiesForDevo]

Manually disabling support for block-templates does work around the issue:

add_action(
	'init',
	function () {
		remove_theme_support( 'block-templates' );
	},
	10,
	0,
);

[britner]

Hi, I can confirm this is a bug introduced in 6.5 and happens if a classic theme has a theme.json file or if a classic theme has enabled block templates through

add_theme_support( 'block-templates' );

[davidbaumwald]

Milestone renamed

[jorbin]

#60973 was marked as a duplicate.

[jorbin]

#60988 was marked as a duplicate.

[grantmkin]

From what I can tell, by testing the wp/v2/templates/lookup endpoint in WP 6.4 and looking through the commit history, the endpoint returning a null item when there are no block templates has been happening for some time. What changed with WP 6.5 was the page editor calling the endpoint on load, revealing the issue.

Modifies the wp/v2/templates/fallback endpoint to return a 404 error when no templates are found.

Trac ticket: https://core.trac.wordpress.org/ticket/60909

[grantmkin]

I've opened the following to address this issue

• ​https://github.com/WordPress/wordpress-develop/pull/6420
• ​https://github.com/WordPress/gutenberg/pull/60925

[wildworks]

A similar issue was reported with Gutenberg: ​https://github.com/WordPress/gutenberg/issues/60974

You can check the error log by accessing the link in the issue.

[jorbin]

Even though it feels unlikely that folks are using this endoint outside of the editor, ruturning a 404 rather than a 200 would be a breaking change that I think should be avoided, especially in a minor release.

What are the thoughts on if $fallback_template is falsey, to skip prepare_item_for_response and keep the return value the same.

[grantmkin]

What are the thoughts on if $fallback_template is falsey, to skip prepare_item_for_response and keep the return value the same.

I don't particularly like the inconsistency of other methods in the templates controller returning a 404 error when a template isn't found, but the fallback route returning a 200 status with an empty response. But I see how this makes sense for a minor release, to minimize changes.

I've updated the wordpress-develop PR to skip prepare_item_for_response and return an empty object when the fallback template isn't found.

[jorbin]

In 58079:

REST API: Return empty object when no fallback templates are found (wp/v2/templates/lookup)

This prevents a number of php notices that are surfaced due to the endpoint being called on load of the post editor even when there are no templates.

Props grantmkin, CookiesForDevo, britner, wildworks, jorbin.
Fixes #60909.

[jorbin]

Reopeing for backport consideration

[joemcgill]

[58079] looks good to backport 👍🏻

[jorbin]

In 58080:

REST API: Return empty object when no fallback templates are found (wp/v2/templates/lookup)

This prevents a number of php notices that are surfaced due to the endpoint being called on load of the post editor even when there are no templates.

Reviewed by joemcgill.
Merges [58079] to the 6.5 branch.

Props grantmkin, CookiesForDevo, britner, wildworks, jorbin.
Fixes #60909.

Thanks! Merged in https://core.trac.wordpress.org/changeset/58079.