项目中，用到了WCF Service服务，用的是Windows身份验证，正常登陆后 HttpContext.Current=null
解决方法——
1.在Web.config文件中添加配置项
<system.serviceModel>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true"/>
</system.serviceModel>
2.在Service类文件上添加Attribute
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
原文：http://www.cnblogs.com/lishidefengchen/p/4317395.html