Home > Hyper-V, Virtualization, Windows 2008 R2 > Hyper-v Error When you connect to VM “An Authentication error has occured.”

Hyper-v Error When you connect to VM “An Authentication error has occured.”

Another interesting problem form Hyper-V forum, Cédric from Hyper-V forum had a problem with new installed Hyper-V server when he tried to connect to VMs.

From the Hyper-V Manager console, when you try to connect to a local VM, no problem. But when i try to connect to a VM owned by another node, you get the following Error.

“Remote Desktop Connection”.
An Authentication error has occured.
The specified data could not be encrypted.
Remote Computer: “FQDN of the targeted host”

All other operation (stop, start etc work perfectly).The cluster validation report was “all green”.

The cluster nodes have this hotfix installed.

  • KB977238 (HV BPA)
  • KB981791 (Stop Error on intel Westmere)
  • And cumulative update 2 for operation manager 2007 R2.

After some digging with MS Support to find the cause of the problem it turns out to be a problem with CredSSP Kerberos ticket length, there is a KB for Windows 2008R2 that solved this issue.


This problem occurs because the CredSSP incorrectly encrypts the data when the size of the security token for the user account exceeds 16 kilobytes (KB).

To resolve this issue, install this hotfix on the terminal server that is running Windows Server 2008 R2 and on any Remote Desktop clients that are running Windows 7 or Windows Server 2008 R2.

  1. November 28, 2010 at 8:45 pm


    I ran into this some time ago. You might want look into this article:


    Hopefully this it will help!

    Maarten Wijsman

  1. September 2, 2010 at 4:03 pm

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