Unknown 500 Internal Server error for Nginx server

I have few sites on a DigitalOcean.com machine and all the sites more or less have same configurations. But as I added a new site it is giving me 500 internal error. Following is the file:

upstream startup_server {
    server 127.0.0.1:9888 fail_timeout=0;

}


server {
    listen 80;
    listen [::]:80;


    root /home/django/startup;
    index index.html index.htm;

    client_max_body_size 4G;
    server_name pitchstartupidea.com www.pitchstartupidea.com;



    keepalive_timeout 5;

    location ~*  \.(jpg|jpeg|png|gif|ico|css|js|woff2|woff|ttf)$ {
        expires 365d;

    }



    # Your Django project's media files - amend as required
    location /media  {
        alias /home/django/startup/media/;
    }

    # your Django project's static files - amend as required
    location static/static-only {
        alias /home/django/startup/static-only/; 

    }
    # Django static images
    location /static/images {
        alias /home/django/startup/static/static-only/images/;
    }


    # Proxy the static assests for the Django Admin panel
    location /static/admin {
       alias /usr/lib/python2.7/dist-packages/django/contrib/admin/static/admin;
    }

    location / {


        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        proxy_pass http://startup_server;
        proxy_connect_timeout 60s;

    }
}

I have my venv located at /home/django/startup and my project is pys at /home/django/startup/pys. Can someone please give me a clue what I might be doing wrong? Currently I am just trying to make it work for pre-production env with "gunicorn --bind pitchyourstartup.com:9888 pys.wsgi:application. Django settings file has ALLOWED_HOST = ['pitchyourstartup.com', 'www.pitchyourstartup.com']and DEBUG = False. I am getting this error while I am trying to access it with pitchyourstartup.com:9888/admin from the browser on my local machine.