Recommended WordPress Update Procedure

Keeping the to WordPress core, Theme and plugins updated and current with the security releases is something that we can't do as each installation is special.
We recommend that the webmaster who designed the Wordpress site makes the updates.

Here is the procedure we recommend from:

1- Make a backup of the site from the Plesk Panel in case something goes wrong with the update.

2- Update WordPress and its plugins according to the WordPress Update instructions (see below).

3- Then if the site does not work fine and you encounter errors during this process, follow the procedure in the Wordpress Update instructions for debugging.

If you are unable to make it work, restore the backup you made just from the Panel before the update.

4- Once the site works well, make another backup of the updated site from the Plesk Panel for possible disaster recovery, and delete the previous one.

Setting up a Maintenance Plan of checking for updates at least once a month.
Subscribing to WordPress' and each Plugin's manufacturer's announcements is recommended.

See Upgrading WordPress - Extended Instructions

Our latest Plesk servers provide WordPress Tools to Upgrade WordPress directly from the Plesk panel,
see: Updating WordPress and its components (Plugins, Themes) on Plesk 12.

If the WordPress installation path given in the Plesk Panel differs from the actual location of the files, you will see either nothing or a list of errors under the WordPress section and so you will NOT be able to update it directly from the Plesk Panel.
Instead you should upgrade from within the WordPress Administration Dashboard.

Here the procedure we recommend for Updating WordPress and its components (Plugins, Themes) in this case:
https://support.his.com/kb/article/460-_Updating_WordPress_and_its_components_(Plugins_Themes)_from_the_WordPress_Dashboard