Groups may not be assigned correctly after a node failure on a Windows Server 2012 R2-based failover cluster

Applies to: Windows Server 2012 R2 DatacenterWindows Server 2012 R2 StandardWindows Server 2012 R2 Essentials

This article describes an issue that occurs if the Anti-Affinity setting is enabled in Windows Server 2012 R2. A hotfix is available to resolve this issue. The hotfix has a prerequisite.


Consider the following scenario:
  • You create a cluster that has at least three nodes.
  • You have groups that have the same value set in each group's AntiAffinityClassNames property.
  • A node has a group that has the AntiAffinityClassNames property set fail.
  • There is at least one surviving node that has no group has the same value in its AntiAffinityClassNames property
In this scenario, the cluster may incorrectly assign the group from the failed node to a surviving node that already has a group with the same value in the AntiAffinityClassNames property. The expected result is that the group from the failed node would be assigned on a surviving node that does not have a group with the same value in its AntiAffintyClassNames property, if one is available.


This issue occurs because, in some cases, the logic that reassigns the groups from failed nodes does not correctly identify which nodes are hosting groups that have matching values in the AntiAffinityClassNames properties.

Hotfix information

Important If you install a language pack after you install this hotfix, you must reinstall this hotfix. Therefore, we recommend that you install any language packs that you need before you install this hotfix. For more information, see Add language packs to Windows.

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.

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, submit a request to 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 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.


To apply this hotfix, you must have April 2014 update rollup for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 (2919355) installed in Windows Server 2012 R2.

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.


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