Upload notification fails with proxy forwarder

XMLHttpRequest cannot load http://host/wiki/subwiki/get/space/page?xpage=attachmentslist&forceTestRights=1. The request was redirected to 'https://host/wiki/subwiki/get/space/page?xpage=attachmentslist&forceTestRights=1', which is disallowed for cross-origin requests that require preflight. 

[blocked] The page at 'https:/host/wiki/subwiki/edit/Project/WebHome' was loaded over HTTPS, but ran insecure content from 'http://host/wiki/subwiki/attach/Project/WebHome': this content should also be loaded over HTTPS.

xwiki.url.protocol=https

upstream rs_80 {
  server localhost:8080;
  # Enter server hosts that NginX should load balance over. See examples commented out below:
  # server 127.0.0.1:18080;
}

server {
  listen    80;
  server_name   *.my_DNS;
  return 301 https://$host:443$request_uri;
}

server {
  error_log /var/log/nginx/xwiki.error.log debug;
  listen    443 ssl;
  server_name   *.my_DNS;

  ssl_certificate      /etc/nginx/ssl/sp.crt;
  ssl_certificate_key  /etc/nginx/ssl/sp.key;

  location / {
    # For CORS
if ($request_method = 'OPTIONS') {
 
        add_header 'Access-Control-Allow-Origin' '$http_origin';
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        
        #
        # Custom headers and headers various browsers *should* be OK with but aren't
        #
 
        add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
        
        #
        # Tell client that this pre-flight info is valid for 20 days
        #
 
        add_header 'Access-Control-Max-Age' 1728000;
        add_header 'Content-Type' 'text/plain charset=UTF-8';
        add_header 'Content-Length' 0;
 
        return 204;
     }
 
     if ($request_method = 'POST') {
 
        add_header 'Access-Control-Allow-Origin' '$http_origin';
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
 
     }
 
     if ($request_method = 'GET') {
 
        add_header 'Access-Control-Allow-Origin' '$http_origin';
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
 
     }
    client_max_body_size 1100m;
  proxy_connect_timeout       600;
  proxy_send_timeout          600;
  proxy_read_timeout          600;
  send_timeout                600;
    proxy_pass                  http://rs_80;
    proxy_next_upstream         error timeout invalid_header http_500 http_502 http_503 http_504;
    proxy_redirect              off;
    proxy_set_header            X-Real-IP $remote_addr;
    proxy_set_header            Host $host;
    proxy_set_header            X-Forwarded-Host $host;
    proxy_set_header            X-Forwarded-Server $host;
    proxy_set_header            X-Forwarded-For $proxy_add_x_forwarded_for;
  }
}