400 Bad Request load balancer for Apache servers with NGINX - apache

Question

I am using NGINX as load balancer for Apache WebServers (WordPress). All servers are made with AWS EC2. My config for NGINX:
cat /etc/nginx/sites-available/default
upstream web_backend {
server 35.157.101.5;
server 35.156.213.23;
}
server {
listen 80;
location / {
proxy_pass http://web_backend;
}
}
But after NGINX restart i am access load balancer via public ip and getting an error:
Bad Request
Your browser sent a request that this server could not understand.
Additionally, a 400 Bad Request error was encountered while trying to
use an ErrorDocument to handle the request.
Apache/2.4.29 (Ubuntu) Server at
ip-172-31-35-36.eu-central-1.compute.internal Port 80
If i refresh page i am getting same error but with another ip in the end (second server’s private ip), so i understand that NGINX do the work and it is Apache problem.
I tried to add 80 port for my servers in nginx config, replace ips with dns and private ip, but it didn’t help. Access log on Apache doesn’t show anything useful, just 400 errors.
What could be the problem?

Answer 1

Don’t use ‘_’ for upstream name, it was the only reason for my problem.

Answer 2

Just check on which ports are the Apache WebServers Running. You have to add those to your upstreams.
E.g.:
upstream web_backend {
server 35.157.101.5:8080; //assuming that your apache webserver is running on this port on this host
server 35.156.213.23:3000;//And a different port on the other.. you still need to add them here if your ports are same
}