我目前正为这个完全相同的问题而苦苦挣扎。如果您的示例可用，请发布解决方案。

I am currently struggling with this exact same issue. If you got your example to work, please post the solution.

似乎您已经根据有关MSDN文档完成了所有必需的操作：

It seems that you have done everything that is required based on the relevant MSDN documentation:

除非另有说明，否则名称，保护，路径，validationKey，validation，decryptionKey和解密属性在所有应用程序中必须相同。同样，用于身份验证票证（cookie数据）的加密和验证密钥值以及加密方案和验证方案必须相同。
MSDN源代码

不过，正如评论中提到的@ NightOwl888一样，您需要在两个应用程序中都设置 enableCrossAppRedirects = true 。

As @NightOwl888 mentioned in the comments though, you need to set enableCrossAppRedirects= true in both applications.

https://docs.microsoft.com/zh-cn/dotnet/api/system.web.security.formsauthentication.enablecrossappredirects?view=netframework-4.7.2

我发现这个较旧的SO问题很有帮助。最终在测试服务器上为我工作，但在生产环境中却没有。必须有其他未记录的相关设置。

I found this older SO question helpful. This ended up working for me on our Test servers, but not in Production. There must be additional undocumented relevant settings.