How do i fix upstream prematurely closed connection error?

I have deployed a django web application to AWS EBS, and one endpoint got a script running for some word processing it takes few seconds(max 10-15 seconds).

I have seen questions and answers for this issue and tried everything, and even changed the django.config file inside .ebextension to following

ption_settings:
  aws:elasticbeanstalk:container:python:
    WSGIPath: alteducation_web.wsgi:application
files:
  "/etc/nginx/conf.d/01-timeout.conf":
     mode: "000644"
     owner: root
     group: root
     content: |
       keepalive_timeout 500s;
       proxy_connect_timeout 500s;
       proxy_send_timeout 500s;
       proxy_read_timeout 500s;
       send_timeout 500s;
       fastcgi_send_timeout 500s;
       fastcgi_read_timeout 500s;
container_commands:
  nginx_reload:
     command: "sudo service nginx reload"

But still the endpoint returns 502 Bad Gateway error,

And logs show the upstream prematurely closed connection error.

how do i get this fix ?

Thanks in advance.