Nginx failed to configure reverse proxy

the server is the centos7.0 server component is nginx

when configuring a reverse proxy, if you want to add this line in the red box,
will report an error. How to solve this problem

Mar.18,2021

proxy_pass replace this line with

set         $admintest "admintest.happymall.com";
resolver    114.114.114.114;
proxy_pass  http://$admintest;
Menu