Website FastCGI sent in stderr: "Unable to open primary script", browser returns a 404 error when accessing PHP pages.
Cause: php-fpm permission issue (using my php-fpm setup as an example)
vi /usr/local/php/etc/php-fpm.conf
service php-fpm restart # Restart; using my startup method as an example
Change the user to match the one in the nginx.conf file.