"Windows has detected an IP address conflict" error in Windows Server 2012 R2 or Windows Server 2008 R2 NLB nodes

Se aplică la: Windows Server 2012 R2 DatacenterWindows Server 2012 R2 StandardWindows Server 2012 R2 Essentials

This article describes an issue that occurs after the live migration is complete in Windows Server 2012 R2 or Windows Server 2008 R2. A hotfix is available to resolve this issue. The hotfix has a prerequisite.


Consider the following scenario:
  • You have a Hyper-V cluster that is running on Windows Server 2008 R2 or a later version of Windows Server.
  • You configure Windows Network Load Balancing (NLB) on two or more virtual machines that are running Windows Server 2012 R2 or Windows Server 2008 R2. The virtual machines are hosted on the same cluster node.
  • You move the NLB virtual machines by concurrent live migration.
  • The live migration is complete.
In this scenario, one or more nodes on the NLB cluster go into a misconfigured status that can be seen in Network Load Balancing Manager. Additionally, you may receive an error message that resembles the following on the misconfigured node:

Windows has detected an IP address conflict
Another computer on this network has the same IP address as this computer. Contact your network administrator for help resolving this issue. More details are available in the Windows System event log.

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.

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 update 2919355 installed in Windows Server 2012 R2. Or, you must install Service Pack 1 for Windows Server 2008 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.


See the terminology that Microsoft uses to describe software updates.