Warning: require_once(config.php): Failed to open stream: No such file or directory in /var/www/php-dev/nav.php on line 4

Fatal error: Uncaught Error: Failed opening required 'config.php' (include_path='.:/usr/share/php') in /var/www/php-dev/nav.php:4 Stack trace: #0 /var/www/php-dev/templates/matrix/header.php(10): renderNavigation() #1 /var/www/php-dev/functions.php(5): require_once('...') #2 /var/www/php-dev/about.php(6): get_theme_header() #3 {main} thrown in /var/www/php-dev/nav.php on line 4