Wordpress website hosted in Plesk shows a 500 error: no such file or directory

Symptoms

• WordPress website shows a blank page or the following error:

  CONFIG_TEXT: 500 - Internal Server Error

• Domains > example.com > Logs shows the following error for one or several files:

  CONFIG_TEXT: AH01071: Got error 'PHP message: PHP Warning: require_once(/var/www/vhosts/example.com/httpdocs/wp-settings.php): failed to open stream: No such file or directory in /var/www/vhosts/example.com/httpdocs/wp-config.php on line 105

Cause

Corrupted WordPress installation. Core WordPress configuration file(s) do not exist on the filesystem.

# ls -la /var/www/vhosts/example.com/httpdocs/wp-settings.php
ls: cannot access '/var/www/vhosts/example.com/httpdocs/wp-settings.php': No such file or directory

Resolution

Restore a website backup with the file(s) as per the following article: How to restore a website file from a Plesk backup