nginx error logs shows worker connection is not enough

Mario asked:

Getting error “500 internal server error” when loading a web page which is an https.
The nginx error.log shows “1024 worker_connections are not enough while connecting to upstream”

The website is behind a nginx reverse proxy. It is working without the reverse proxy. Another website behind the proxy is working.

nginx version: nginx/1.16.0

Tried increasing the work connections all the way up to 20480. The configurations seems fine to me. Could be wrong. Here are the configurations files. Reloaded nginx, restarted nginx.

nginx.conf

user  nginx;
worker_processes   8;
worker_rlimit_nofile 100480;
error_log  /var/log/nginx/error.log warn;
pid        /var/run/nginx.pid;


events {
    worker_connections  1024;
}

#Use multiple worker processes
#work_processes auto;

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    keepalive_timeout  65;

    #gzip  on;

    include /etc/nginx/conf.d/*.conf;

    #disable server tokens
    server_tokens off;

}

server.conf

server {
    listen 80;
    server_name example.com www.example.com;
    return 301 https://example.com$request_uri;

}


server {
   listen 443 ssl;
   server_name example.com www.example.com;

   ssl_certificate         /etc/nginx/cert.pem;
   ssl_certificate_key     /etc/nginx/cert.key;
   ssl_trusted_certificate /etc/nginx/cert.crt;

   location / {
        proxy_pass https://example.com;

   }

   location = /favicon.ico {
        log_not_found off;
        access_log off;
    }

}

Any assistance is appreciated.