An error code is returned when a Kerberos client requests a TGT against a Windows Server 2008-based domain controller: "KERB5KDC_ERR_C_PRINICPAL_UNKNOWN"

Applies to: Windows Server 2008 StandardWindows Server 2008 EnterpriseWindows Server 2008 Datacenter


Consider the following scenario:
  • A Massachusetts Institute of Technology (MIT) Kerberos client performs Kerberos authentication against a Windows Server 2008-based domain controller.
  • KTPass was used to create a keytab file to be used on the MIT Kerberos client.
  • The client requests a ticket-granting ticket (TGT) by specifying the host principal name as the client name in the KRB_AS_REQ packet.

In this scenario, authentication fails, and the following error code is returned:
This problem may occur when a third-party implementation of a Kerberos client interoperates with a Windows Server 2008-based domain controller. For example, this problem may occur if a principal name in the "service/" format is used to generate a keytab file.


Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Important Windows Vista and Windows Server 2008 hotfixes are included in the same packages. However, only one of these products may be listed on the “Hotfix Request” page. To request the hotfix package that applies to both Windows Vista and Windows Server 2008, just select the product that is listed on the page.


This hotfix cannot be installed on the computer unless the Active Directory Domain Services (AD DS) role is installed. If this role is not installed on the computer, the hotfix cannot be successfully installed, and the following error is returned:
The update does not apply to your system
For more information about how to add the AD DS role, visit the following Microsoft Web site:

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.
Windows Server 2008, x86-based versions
File nameFile versionFile sizeDateTimePlatform
Kdcsvc.mofNot applicable5,30018-Dec-200721:27Not applicable
Windows Server 2008, x64-based versions
File nameFile versionFile sizeDateTimePlatform
Kdcsvc.mofNot applicable5,30018-Dec-200721:27Not applicable


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates