[php] File Not Found when running PHP with Nginx

The error message “Primary script unknown or in your case is file not found.” is almost always related to a wrongly set in line SCRIPT_FILENAME in the Nginx fastcgi_param directive (Quote from https://serverfault.com/a/517327/560171).

In my case, I use Nginx 1.17.10 and my configuration is:

    location ~ \.php$ {
      fastcgi_pass unix:/var/run/php/php7.2-fpm.sock;
      fastcgi_index index.php;
      fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;
      include fastcgi_params;
      fastcgi_read_timeout 600;
    }

You just change $document_root to $realpath_root, so whatever your root location, like /var/www/html/project/, you don't need write fastcgi_param SCRIPT_FILENAME /var/www/html/project$fastcgi_script_name; each time your root is changes. This configuration is more flexible. May this helps.

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For more information, if you got unix:/run/php/php7.2-fpm.sock failed (13: Permission denied) while connecting to upstream, just change in /etc/nginx/nginx.conf, from user nginx; to user www-data;.

Because the default user and group of PHP-FPM process is www-data as can be seen in /etc/php/7.2/fpm/pool.d/www.conf file (Qoute from https://www.linuxbabe.com/ubuntu/install-nginx-latest-version-ubuntu-18-04):

user = www-data
group = www-data

May this information gives a big help