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


  • Since the Microsoft Security Patch on Tuesday, we've received many reports of users having connection problems like this:

    An authentication error has occurred.
    The function requested is not supported
    Remote computer: <computer name="">
    This could be due to CredSSP encryption oracle remediation.
    For more information, see https:/

    The error impacts:

    • Remote Desktop Connection
    • Remote Desktop Connecting to Azure VMs
    • VPN Network Connections (before one can even try to use Remote Desktop)

    This is quite a mess and seems to be related to the security patch increasing security requirements, but not implementing the change to give the machine the increased security levels. The latter doesn't seem to occur if the machine has automated Windows Updates turned off.

    Unfortunately, Windows Update can't be automated in many environments such as development, build, test, staging and production without creating other problems.

    Wrote a blog post about our findings so far with a workaround on how to reduce Remote Desktop security settings to get around this problem. It doesn't require touching registry settings or other complicated steps:

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

    Would appreciate any insight on handling this across an enterprise without manually modifying the connecting and host machines.

    A common scenario is a person working from home not being able to connect to their own computer in the office or a VM.


    Luke Chung
    Microsoft MVP
    President of FMS, Inc.
    Blog Facebook Twitter

    2018年5月11日 12:50


  • Here is the FIX for this issue ..

    --> Change the Group Policy on your local client to use the vulnerable setting 

    Run:  gpedit.msc

    Go to à Computer Configuration -> Administrative Templates -> System -> Credentials Delegation -> Encryption Oracle Remediation

    Open - Encryption Oracle Remediation à  choose Enable  à change protection level àVulnerable à Apply

    Thanks and Regards,


    • 回答の候補に設定 vor0nwe 2018年5月16日 10:22
    • 回答としてマーク LukeChungMVP 2018年5月24日 18:29
    2018年5月14日 13:40