Remote Desktop突然不能用了 “This could be due to CredSSP encryption oracle remediation”

一段时间没有用RDP去连远程的Windows主机，某一天突然发现用不了了。

错误信息如下：

An authentication error has occurred.
The function requested is not supported

Remote computer: 10.2XX.XXX.XXX
This could be due to CredSSP encryption oracle remediation.
For more information, see https://go.microsoft.com/fwlink/?linkid=866660

查了点资料，发现这是由于安装了KB4103727（Windows 10 Version 1709） 或者KB4103718 （Windows 7），其目的是修复了一些安全方面的问题。但是，副作用就是导致了RDP不能用了。

有四个解决方案。笔者试验了第二个，修改group policy，成功的解决了这个问题。

具体步骤如下：

运行: gpedit.msc

打开 Computer Configuration -> Administrative Templates -> System -> Credentials Delegation -> Encryption Oracle Remediation

打开Encryption Oracle Remediation, 选择Enable，然后修改protection level 为Vulnerable，点Apply。

问题解决。

参考资料

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[Solved] RDP Authentication Error Function Requested Is Not Supported

https://www.itechtics.com/solved-authentication-error-function-requested-is-not-supported/

Remote Desktop Authentication Error Has Occurred. The function requested is not supported.

https://social.technet.microsoft.com/Forums/Lync/en-US/46e1cd52-52b3-4427-88a3-200f87319e23/remote-desktop-authentication-error-has-occurred-the-function-requested-is-not-supported?forum=w7itpronetworking