在flex中一般使用navigateToUrl请求服务下载内容，最近客户反映下载失败(flash15)。而本机测试都是好的(flash11)，可以进行请求下载
没有任何思路，求助大谷歌，发现flash安全机制提高了https://bugbase.adobe.com/index.cfm?event=bug&id=3759971
以下摘自文中chris.campbell解释
Our security model does not allow a movie to send HTTP headers across domains, unless the player has confirmed the receiving domain permits it with a cross domain policy file ( see http://adobe.ly/1oy1g8e ).
我们安全策略模型是不允许跨域进行发送HTTP消息头，除非接收到跨域策略文件进行允许
With navigateToUrl() we are unable to detect server-side redirects, so we are unable to confirm the actual recipient has permits HTTP headers. To resolve this, we elected to block HTTP headers from all navigateToUrl requests.
而是用
navigateToUrl()我们无法检测到服务端重定向了，不能确定接收方是否允许http消息头。因此，我们选择禁止HTTP消息头As noted by several customers, this has proved to be overly restrictive, so we are going to relax the restriction to allow simple headers with navigateToUrl requests.
正如一些用户指出，这个过于限制了，所以我们又进行放松限制，允许一些简单的消息头
Simple headers are defined by Cross-Origin Resource Sharing (http://bit.ly/1oy1kVp) as:
这些消息头在跨域资源共享有相关定义
A header is said to be a simple header if the header field name is an ASCII case-insensitive match for Accept, Accept-Language, or Content-Language or if it is an ASCII case-insensitive match for Content-Type and the header field value media type (excluding parameters) is an ASCII case-insensitive match for application/x-www-form-urlencoded, multipart/form-data, ortext/plain.
一个称之为简单消息头定义如下，属性名只能是
Accept,Accept-Language,Content-Language以及Content-Type，而当属性名是Content-Type时，值只能为application/x-www-form-urlencoded,multipart/form-data,ortext/plain,以上字符不区分大小写In an upcoming Flash Player build, navigateToUrl() will be changed to throw the exception only when called with an URLRequest containing non-simple headers. We’re shooting to get this change in for our July release but this will of course depend on our testing results. We’ll be getting this into a public beta as soon as possible (possibly as soon as the next week or two.)
后续flash版本
navigateToUrl当URLRequest包含非简单消息头时会抛出异常
产品系统在定义请求消息体时，URLRequest设置method为post方式，而后设置content-type值为application/octet-stream,导致在flash13+上报Security error #3769错误
解决办法，删除消息头content-type的定义，测试通过没有异常