Error with 4.5.8

Hi,

I’m experiencing an issue after updating the Duplicate Page plugin from version 4.5.7 to 4.5.8.

My site uses both Duplicate Page and the Sendify Campaign plugin. Since updating to 4.5.8, duplicating my campaigns no longer works. If I roll back to version 4.5.7, everything works correctly again.

Here is the error message I’m getting:

Uncaught Error: The script tried to modify a property on an incomplete object. Please ensure that the class definition "stdClass" 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 /wp-includes/formatting.php:5157

Stack trace: 0 /wp-includes/formatting.php(5152): map_deep() 1 /wp-includes/formatting.php(5152): map_deep() 2 /wp-includes/formatting.php(5152): map_deep() 3 /wp-includes/formatting.php(5152): map_deep() 4 /wp-includes/formatting.php(2861): map_deep() 5 /wp-includes/formatting.php(5814): stripslashes_deep() 6 /wp-includes/meta.php(63): wp_unslash() 7 /wp-includes/post.php(2658): add_metadata() 8 /wp-content/plugins/duplicate-page/duplicatepage.php(221): add_post_meta() 9 /wp-content/plugins/duplicate-page/duplicatepage.php(122): duplicate_page->duplicate_edit_post() 10 /wp-includes/class-wp-hook.php(341): duplicate_page->dt_duplicate_post_as_draft() 11 /wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters() 12 /wp-includes/plugin.php(522): WP_Hook->do_action() 13 /wp-admin/admin.php(424): do_action() 14 {main}

It seems related to how metadata is handled during duplication, possibly involving serialized objects.

Could you please advise if this is a known issue in 4.5.8, or if there is a workaround or fix available?

Thank you for your help.