Although plesk allows you to enable or dissable safe mode for a domain, there is no where you can dissable or enable safe mode for a sub domain !
The answer lies in the Plesk apache Config File, Safe mode can be switched off from within the file
/var/www/vhosts/domain.com/subdomains/<subdomain-name>/conf/vhost.conf
<Directory /var/www/vhosts/domain.com/subdomains/<subdomain-name>/httpdocs>
php_admin_flag safe_mode off
</Directory>
Then, as with every time you edit such a config file, you will need to tell plesk about the change
/usr/local/psa/admin/sbin/websrvmng –reconfigure-vhost –vhost-name=domain.com
And you will need to tell apache to reload it’s config files…
/etc/rc.d/init.d/httpd restart
You should now be good to go

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