Updating WordPress on Plesk Obsidian
WordPress, its Theme and plugins need to be kept updated as vulnerabilities are discovered on a regular basis, and hackers are scanning the internet for vulnerable web sites to exploit.
You will fin a good write up about Upgrading WordPress on the WordPress Codex:
Here is a link to the procedure we recommend for Updating WordPress and its components (Plugins, Themes).
If WordPress has been setup using the Plesk WordPress Toolkit, you can also update it right from your domain's the Plesk Panel: