CORS 预检请求的奇怪问题在 IE 11 上失败

问题是 POST 查询在 IE11 上失败，在所有其他浏览器中它似乎都可以工作。

让我们一步一步地描述问题：

1. 从应用程序到 REST API 的 XHR 请求。
2. 印前检查选项请求（请求参数如下）

Accept:                         */*
Origin:                         https://app.example.com
Access-Control-Request-Method:  POST
Access-Control-Request-Headers  content-type, accept
:                               
Accept-Encoding:                gzip, deflate
User-Agent:                     Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko
Host:                           api.example.com
Content-Length:                 0
Connection:                     Keep-Alive
Cache-Control:                  no-cache

2. 印前检查请求响应参数包括：

X-Powered-By:                   Sugar
Access-Control-Allow-Origin:    https://app.example.com
Vary:                           Origin
Access-Control-Allow-Credentia  true
ls:                             
Access-Control-Allow-Methods:   GET,POST,DELETE,OPTIONS
Access-Control-Allow-Headers:   X-Requested-With,X-HTTP-Method-Override,Content-Type,Accept
set-cookie:                     sugar.sid=s%Pb9OoTTPUkVw%2F2vUPoFMNG
                                LMXACSkQevo; Path=/; Expires=Thu, 15 Jan 2015 18:27:07 GMT; HttpOnly; Secure
Date:                           Mon, 12 Jan 2015 18:27:07 GMT
Connection:                     close

3. 预检后的真实 HTTP 请求参数：

Accept:           application/json
Content-Type:     application/json
Referer:          https://app.example.com/
Accept-Language:  en-US
Origin:           https://app.example.com
Accept-Encoding:  gzip, deflate
User-Agent:       Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko
Host:             api.example.com
Content-Length:   9
Connection:       Keep-Alive
Cache-Control:    no-cache
Cookie:           sugar.sid=s%3A-%2FGF1YoFmRfmBsxK4vLBoGjY5NT0QoYvf5s;

4. 最后响应参数：

Content-Type:    application/json; charset=utf-8
Content-Length:  72
Vary:            Accept-Encoding
Date:            Mon, 12 Jan 2015 18:27:07 GMT
Connection:      close

5. 基本上响应以IE错误结束：原产地：https://app.example.com 在访问控制允许源头中找不到。第一个请求是否还需要似乎缺少的访问-**-源标头。

也按照CORS流程图调试问题，但我 http://www.html5rocks.com/static/images/cors_server_flowchart.png 无法发现它。

我正在使用带有node-cors模块+修改选项的Node.js Express服务器。

HTTP/1.1 400 Bad Request
Cache-Control: no-cache
Pragma: no-cache
Content-Type: application/json; charset=utf-8
Expires: -1
Server: Microsoft-IIS/8.5
X-AspNet-Version: 4.0.30319
X-Frame-Options: SAMEORIGIN
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Date: Mon, 12 Sep 2016 19:40:20 GMT
Content-Length: 103
{"Message":"The collection of headers 'accept,if-modified-since,cache-control,pragma' is not allowed."}