Problem with directory / files permissions after installing some software on your Plesk Linux server ( Nagios for example known to cause this in certain scenarios ).

From /var/www/vhosts/domain.com/statistics/logs/error_log :

[critical] [client 192.168.0.13] (13)Permission
denied: /var/www/vhosts/domain.com/httpdocs/.htaccess pcfg_openfile:
unable to check htaccess file, ensure it is readable

You will see Forbidden Error in your browser.

If you check the mentioned location you will notice that .htaccess file is probably not even there. Creating it and giving it the correct permissions won’t help of course.

In our case permissions set wrong on the httpdocs / httpsdocs directory itself.
Try this to fix:

cd /var/www/vhosts/domain.com/
chmod 755 httpdocs
chmod 755 httpsdocs

You don’t have to set the permissions to 755 as 751 for example will work as well. Play with the permissions on httpdocs to find the suitable solution.