Nginx Reverse Proxy with custom error if upstream proxy is not working.

gistfile1.nginxconf

server {
    listen 80;
    listen [::]:80 default server ipv6only=on;
    
    location / {
        proxy_intercept_errors on;
        proxy_pass http://localhost:9000;
    }
    
    error_page 500 502 503 504 /50x.html;
    
    location = /50x.html {
        root /var/www/errors;
    }
}

Thanks for sharing