500 internal server error Akka Nginx - nginx

Question

I am trying to run Akka service using nginx. Here is my default.conf:
upstream hello-akka{
server localhost:9000;
}
server {
listen 9000;
location /* {
root /usr/share/nginx/html;
index index.html index.htm;
}
location /akka {
proxy_pass http://hello-akka;
}
location /assets {
root /var/www;
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root /usr/share/nginx/html;
}
}
Default nginx page works just fine but when I redirect to /akka I get 500 internal server error. Here is my nginx log file:
2017/12/05 10:58:17 [crit] 11077#11077: *1014 open() "/usr/share/nginx/html/50x.html" failed (24: Too many open files), client: 127.0.0.1, server: , request: "GET /akka HTTP/1.0", upstream: "http://127.0.0.1:9000/akka", host: "hello-akka"
I have changed /etc/security/limits.con file to increase the number of connections from 1024 to 16384. However, after that I keep getting another error:
host: "hello-akka"
2017/12/05 11:40:42 [error] 15916#15916: *37494 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 127.0.0.1, server: , request: "GET /akka HTTP/1.0", upstream: "http://127.0.0.1:9000/akka"
So what is wrong with my configurations and how should I change them to run /akka page normally?
UPDATE: I have changed server localhost:9000 to server localhost:8080 in upstream hello-akka. However, when I redirect to localhost:9000/akka I get An error occurred page.
Error logs shows this error:
*1 connect() failed (111: Connection refused) while connecting to upstream, client: 127.0.0.1, server: , request: "GET /akka HTTP/1.1", upstream: "http://127.0.0.1:8080/akka", host: "localhost:9000"