If you want to customize error page, here is how:

Create /home/wwwroot/frequent_used/404.html and /home/wwwroot/frequent_used/403.html, add following code into your nginx config file. And nginx -s reload or systemctl restart nginx.

        error_page 404 = /404.html;
        error_page 403 = /403.html;


        location = /404.html {
            root /home/wwwroot/frequent_used;
            internal;
            allow all;
        }

        location = /403.html {
            root /home/wwwroot/frequent_used;
            internal;
            allow all;
        }