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我正在尝试在Visual Studio 2013中的新MVC 5项目中设置集成的OWIN Facebook身份验证.我已根据本教程配置了应用程序和密钥:

http://www.asp.net/mvc/tutorials/mvc-5/create-an-aspnet-mvc-5-app-with-facebook-and-google-oauth2-and-openid-sign-on

但是,我在AccountController中从此调用中抛出了NullReferenceException:

    [AllowAnonymous]
    public async Task<ActionResult> ExternalLoginCallback(string returnUrl)
    {
        var loginInfo = await AuthenticationManager.GetExternalLoginInfoAsync();

我已经检查了Fiddler的回复,并且得到了Facebook的成功回复,但仍然得到了这个错误.响应如下:

{"id":"xxx","name":"xxx","first_name":"xxx","last_name":"xxx","link":
"https:\/\/www.facebook.com\/profile.php?id=xxx","location":{"id":"xxx","name":"xxx"},
"gender":"xxx","timezone":1,"locale":"en_GB","verified":true,"updated_time":"2013-10-23T10:42:23+0000"}

我在http和https中进行调试时得到了这个.我猜这是一个框架错误,但迄今为止通过反射器诊断出这一点.