An update is available for Windows Server 2008-based computers to address issues with backing up and restoring Hyper-V virtual machines

This article describes the issues that are fixed in this Hyper-V update for Windows Server 2008-based computers that have the Hyper-V role enabled.

Issue 1

If you back up a Hyper-V virtual machine that has multiple volumes, the backup may fail. If you check the VMMS event log after the backup failure occurs, the following event is logged:

Log Name: Microsoft-Windows-Hyper-V-VMMS-Admin
Source: Microsoft-Windows-Hyper-V-VMMS
Event ID: 10104
Level: Error
Failed to revert to VSS snapshot on one or more virtual hard disks of the virtual machine '%1'. (Virtual machine ID %2)

Issue 2

The Microsoft Hyper-V VSS Writer may enter an unstable state if a backup of the Hyper-V virtual machine fails. If you run the vssadmin list writers command, the Microsoft Hyper-V VSS Writer is not listed. To return the Microsoft Hyper-V VSS Writer to a stable state, the Hyper-V Virtual Machine Management service must be restarted.

Issue 3

You cannot restore a Hyper-V virtual machine if the virtual machine was configured to use a legacy network adapter.
To resolve this issue, install the service pack or update that is described in this section. After you install the update on the Host computer, you have to install the updated Integration Components on each Guest computer before this update becomes fully effective. To do this, open the Virtual Machine Connection for the Guest computer in Hyper-V Manager, and then select the Insert Integration Services Setup Disk option on the Action menu. Installation of the Integration Services starts automatically on the Guest computer, but you must click Yes to continue.

  • On a Windows Server 2008-based computer, the updated Integration Services are listed as KB960242 in the Programs and Features item in Control Panel.
  • On a Windows Vista-based computer, the updated Integration Services are listed as KB960243 in the Programs and Features item in Control Panel.

Service Pack Information

To resolve this problem, obtain the latest service pack for Windows Server 2008. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
968849 How to obtain the latest service pack for Windows Server 2008

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 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, 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.


Before you apply this update, the release version of Hyper-V must be installed. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
950050 Description of the update for the release version of the Hyper-V technology for Windows Server 2008

Restart requirement

You have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other previously released hotfixes.

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 file information notes

The .manifest files and the .mum files that are installed in each environment are listed separately in the "Additional file information for 64-bit versions of Windows Server 2008" section. These files and their associated .cat (security catalog) files are critical to maintaining the state of the updated component. The .cat files are signed with a Microsoft digital signature. The attributes of these security files are not listed.
Windows Server 2008, 64-bit versions
File nameFile versionFile sizeDateTimePlatform
Vmms.exe6.0.6001.223523,872,25613-Jan-2009 02:42 x64
Blank.vfdNot Applicable1,474,56018-Dec-200721:18Not Applicable
Vid.dll6.0.6001.2235237,88813-Jan-200905:01 x64
Vmbuspipe.dll6.0.6001.2235215,87213-Jan-2009 05:01 x64
Vmbusvdev.dll6.0.6001.2235283,96813-Jan-2009 05:01 x64
Vmguest.isoNot Applicable42,584,06421-Dec-2008 23:20 Not Applicable
Vmprox.dllNot Applicable178,68813-Jan-200905:01x64
Windowsvirtualization.mofNot Applicable406,53613-Jan-200900:52 Not Applicable
Windowsvirtualizationuninstall.mofNot Applicable57211-Jul-200820:06Not Applicable
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
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

Additional file information for 64-bit versions of Windows Server 2008

File nameFile versionFile sizeDateTimePlatform
Amd64_5ea2a0e012fba496634951da2e3c633f_31bf3856ad364e35_6.0.6001.22352_none_898535921950c54c.manifestNot Applicable70314-Jan-200900:09Not Applicable
Amd64_08d4dc4f14b70e82efea40a20802f63d_31bf3856ad364e35_6.0.6001.22352_none_c03e75641cbceedb.manifestNot Applicable69814-Jan-200900:09Not Applicable
Amd64_microsoft-hyper-v-vstack-vmms_31bf3856ad364e35_6.0.6001.22327_none_932fa5e93071aa4d.manifestNot Applicable249,723 13-Jan-20095:28Not Applicable
Amd64_microsoft-hyper-v-vstack_31bf3856ad364e35_6.0.6001.22327_none_c157114ac5a25cab.manifest Not Applicable45,50813-Jan-20095:23Not Applicable
Package_1_for_kb959962~31bf3856ad364e35~amd64~~ Not Applicable2,56314-Jan-200900:09Not Applicable
Package_2_for_kb959962~31bf3856ad364e35~amd64~~ Applicable2,56314-Jan-200900:09Not Applicable
Package_for_kb959962_sc_0~31bf3856ad364e35~amd64~~ Applicable1,52814-Jan-200900:09Not Applicable
Package_for_kb959962_sc~31bf3856ad364e35~amd64~~ Applicable1,43014-Jan-200900:09Not Applicable
Package_for_kb959962_server_0~31bf3856ad364e35~amd64~~ Applicable1,53214-Jan-200900:09Not Applicable
Package_for_kb959962_server~31bf3856ad364e35~amd64~~ Applicable1,43814-Jan-200900:09Not Applicable

Article ID: 959962 - Last Review: 10/08/2011 01:19:00 - Revision: 4.0

Windows Server 2008 Datacenter, Windows Server 2008 Enterprise, Windows Server 2008 Standard

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