“We're sorry, but something went wrong” : rails + nginx + puma + digitalocean + ssl

Question

I just successfully configured ssl on my rails app on the production server, but now, when I try to access the site I got "We're sorry, but something went wrong." error:

If I disable ssl by not using any ssl setting, my Rails app will run just fine. It's only when I use the ssl setting, that I will have this problem. Which suggest that there is nothing wrong with my Rails code or something.

I already checked these logs files : "production.log puma.access.log puma.error.log" but there are nothing there except for :

=== puma startup: 2017-02-08 21:18:32 +0000 ===
* Listening on unix:///home/deploy/apps/my_app/shared/tmp/sockets/my_app-puma.sock

And below is my nginx.conf setting:

upstream myapp_puma {
  #server unix:/tmp/myapp_puma.sock fail_timeout=0;
  server unix:///home/deploy/apps/my_app/shared/tmp/sockets/puma.sock;
}

# for redirecting to https version of the site
server {
       listen 80;
       rewrite ^(.*) https://$host$1 permanent;
 }

# for redirecting to non-www version of the site
server {
    listen  80;
    server_name  my.my_app.com;
    rewrite ^(.*) http://my.my_app.com$1 permanent;
}


server {
  listen  443 default ssl;
  server_name my.my_app.com;
  root /home/deploy/apps/my_app/current/public;

  access_log /home/deploy/apps/my_app/current/log/nginx.access.log;
  error_log /home/deploy/apps/my_app/current/log/nginx.error.log info;

  ssl on;
  ssl_certificate /etc/letsencrypt/live/my.my_app.com/fullchain.pem;
  ssl_certificate_key /etc/letsencrypt/live/my.my_app.com/privkey.pem;

  ssl_session_timeout  5m;

  ssl_protocols  SSLv2 SSLv3 TLSv1;
  ssl_ciphers  HIGH:!aNULL:!MD5;
  ssl_prefer_server_ciphers   on;

  location ^~ /assets/ {
    gzip_static on;
    expires max;
    add_header Cache-Control public;
  }

  try_files $uri/index.html $uri @myapp_puma;
  location @myapp_puma {
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-Proto https;
    proxy_redirect off;
    proxy_pass http://myapp_puma;
  }

  error_page 500 502 503 504 /500.html;
  client_max_body_size 4G;
  keepalive_timeout 10;
}