could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied) code example

Example: nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied)

sudo chown -R www-data:www-data /var/log/nginx;
sudo chmod -R 755 /var/log/nginx;