Why there are changes in WordPress core files in a WordPress instance that was installed from Plesk Application catalog?

Question

Why there are changes in WordPress core files (wp-admin/includes/upgrade.php, wp-includes/functions.php and wp-includes/load.php) in a WordPress instance that was installed from Plesk Application catalog?

Answer

The mentioned changes in the WordPress core files wp-admin/includes/upgrade.php, wp-includes/functions.php and wp-includes/load.php​ are part of the expected behavior of the Plesk Application Catalogue: These changes are implemented during WordPress instance installation from Domains > example.com > Applications.

It is recommended to install WordPress instances via WP Toolkit from Plesk > WordPress > Install. When a WordPress instance is installed via WP Toolkit, no changes are implemented in the WordPress core files.