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Can't log on after changing machine account password in mixed Windows Server 2012 R2 and Windows Server 2003 environment

Consider the following scenario:
  • You have domain controllers that are running Windows Server 2003 or Windows Server 2012 R2 in a domain.
  • You have a domain-joined computer that authenticates against a Windows Server 2003-based domain controller first, and then the computer authenticates against a Windows Server 2012 R2-based domain controller.
  • You log on the computer and change the machine account password two times.
  • You log on the computer again.
In this scenario, you receive the following error message:

unknown username or bad password

Additionally, following event is logged in the event log:

Event ID: 4

Source: Kerberos

Type: Error

"The Kerberos client received a KRB_AP_ERR_MODIFIED error from the server host/ This indicates that the password used to encrypt the Kerberos service ticket is different than that on the target server. Commonly, this is due to identically named machine accounts in the target realm (, and the client realm. Please contact your system administrator."

The Kerberos client depends on a salt from the Key Distribution Center (KDC) in order to create the Advanced Encryption Standard (AES) keys on the client-side. These AES keys are used to hash the password that the user enters on the client, and protect the password in transit over the wire so that the password cannot be intercepted and decrypted. The salt refers to information that is fed into the algorithm that is used to generate the keys so that the KDC can verify the password hash and issue tickets to the user. When a Windows 2012 R2 domain controller is added in an environment where Windows Server 2003 domain controllers are present, there is a mismatch in the encryption types that are supported on the KDCs and used for salting. Windows Server 2003 domain controllers do not support AES and Windows Server 2012 R2 domain controllers do not support Data Encryption Standard (DES) for salting.
How to obtain this update or hotfix
To resolve this issue, we have released a hotfix and an update rollup for Windows Server 2012 R2 in which Active Directory is installed.

Before you install this hotfix, check the prerequisite of the hotfix.

The update rollup fixes many other issues in addition to the issue that the hotfix fixes. We recommend that you use the update rollup. The update rollup is larger than the hotfix. Therefore, the update rollup takes longer to download.

Note After the update is installed, we recommend you restart all client computers that support Advanced Encryption Standard (AES) encryption. This is to recover the clients if they had previously restarted against a Windows Server 2012 R2 domain controller that does not have the update installed.

Update for Windows Server 2012 R2

The following update rollup is available:

Hotfix for Windows Server 2012 R2

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. 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, go to the following Microsoft website: 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.

Hotfix detail information

To apply this hotfix, you must first install update 2919355 on Windows Server 2012 R2. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
2919355 Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 Update April, 2014
Registry information
To use the hotfix in this package, you do not have to make any changes to the registry.
Restart requirement
You may have to restart the computer after you apply this hotfix.
Hotfix replacement information
This hotfix does not replace a previously released hotfix.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
More information

File information

The global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows Server 2012 R2 file information notes

Important Windows 8.1 hotfixes and Windows Server 2012 R2 hotfixes are included in the same packages. However, only "Windows 8.1" is listed on the Hotfix Request page. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 8.1" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    VersionProductMilestoneService branch
    6.3.960 0.17 xxxWindows Server 2012 R2RTMGDR
  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows RT 8.1 and Windows 8.1" section. MUM, MANIFEST, and the associated security catalog (.cat) files, are very important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
For all supported x64-based versions of Windows Server 2012 R2
File nameFile versionFile sizeDateTimePlatform
Kdcsvc.mofNot applicable5,30018-Jun-201315:04Not applicable

Additional file information

Additional file information for Windows Server 2012 R2
Additional files for all supported x64-based versions of Windows Server 2012 R2
File propertyValue
File nameAmd64_63632cd4fcc6199ef1ab18a6950ab28e_31bf3856ad364e35_6.3.9600.17276_none_ec71b630bfa22849.manifest
File versionNot applicable
File size724
Date (UTC)04-Aug-2014
Time (UTC)13:49
PlatformNot applicable
File nameAmd64_microsoft-windows-k..distribution-center_31bf3856ad364e35_6.3.9600.17276_none_7c82e02d682e1c97.manifest
File versionNot applicable
File size58,811
Date (UTC)04-Aug-2014
Time (UTC)02:27
PlatformNot applicable
For more information about the workaround for this issue, go to the following Microsoft website: 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

Article ID: 2989971 - Last Review: 09/28/2014 08:00:00 - Revision: 3.0

Windows Server 2012 R2 Datacenter, Windows Server 2012 R2 Standard, Windows Server 2012 R2 Essentials, Windows Server 2012 R2 Foundation

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