The script tried to modify a property on an incomplete object.

• I've searched for any related issues and avoided creating a duplicate issue.

Please give us a description of what happened

Recently, the function "new draft" in the post list started throwing an uncaught PHP error and shows the white screen with "Your page encountered a severe issue." instead of the WP admin backend. Something goes wrong inside the duplicate_post function as it looks...

To Reproduce

Step-by-step reproduction instructions

1. In the post list, click on "New draft"

Expected results

1. The post is cloned into a new draft without errors.

Actual results

1. The post is cloned into a new draft and an uncaught PHP error is issued: The script tried to modify a property on an incomplete object.

Screenshots, screen recording, code snippet

[30-Jul-2023 08:16:07 UTC] PHP Fatal error: Uncaught Error: The script tried to modify a property on an incomplete object. Please ensure that the class definition "Wpil_Model_Link" of the object you are trying to operate on was loaded before unserialize() gets called or provide an autoloader to load the class definition in /var/web/site/public_html/wp-includes/formatting.php:5058

PHP Stacktrace:

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/var/web/site/public_html/wp-includes/formatting.php(5053): map_deep(Object(__PHP_Incomplete_Class), 'duplicate_post_...')
/var/web/site/public_html/wp-content/plugins/duplicate-post/admin-functions.php(400): map_deep(Array, 'duplicate_post_...')
/var/web/site/public_html/wp-content/plugins/duplicate-post/admin-functions.php(424): duplicate_post_addslashes_deep(Array)
/var/web/site/public_html/wp-content/plugins/duplicate-post/admin-functions.php(386): duplicate_post_wp_slash(Array)
/var/web/site/public_html/wp-includes/class-wp-hook.php(310): duplicate_post_copy_post_meta_info(19351, Object(WP_Post))
/var/web/site/public_html/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters('', Array)
/var/web/site/public_html/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
/var/web/site/public_html/wp-content/plugins/duplicate-post/admin-functions.php(721): do_action('dp_duplicate_po...', 19351, Object(WP_Post), 'draft')
/var/web/site/public_html/wp-content/plugins/duplicate-post/src/handlers/link-handler.php(87): duplicate_post_create_duplicate(Object(WP_Post), 'draft')
/var/web/site/public_html/wp-includes/class-wp-hook.php(308): Yoast\WP\Duplicate_Post\Handlers\Link_Handler->new_draft_link_action_handler('')
/var/web/site/public_html/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters('', Array)
/var/web/site/public_html/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
/var/web/site/public_html/wp-admin/admin.php(419): do_action('admin_action_du...')
{main} thrown in /var/web/site/public_html/wp-includes/formatting.php on line 5058

Technical info

• If relevant, which editor is affected (or editors):

• Block Editor
• Gutenberg Editor
• Classic Editor
• Other:

• Which browser is affected (or browsers):

• Chrome
• Firefox
• Safari
• Other:

Used versions

• Device you are using: HP ENVY x360
• Operating system: Windows 11 Home
• PHP version: 8.0
• WordPress version: 6.2.2
• WordPress Theme: Astra 4.1.6
• Yoast Duplicate Post version: 4.5
• Gutenberg plugin version:
• Classic Editor plugin version:
• Relevant plugins in case of a bug:

Start by tracing the new-draft flow from src/handlers/link-handler.php through duplicate_post_create_duplicate() and admin-functions.php, especially duplicate_post_copy_post_meta_info() and the deep-slash helpers around lines 386-424. Reproduce the failure from the post list with the listed WordPress, PHP, and plugin versions. Done means New draft creates a cloned draft without the incomplete-object fatal error.