Windows could not parse or process the unattend answer file for pass [specialize]

I was at a customer which I have deployed vCloud Automation Center 6.1 for, and they tried to create a new blueprint. They have copied the old blueprint and only changed the VM template used in that blueprint from Windows 2012 to Windows 2008 R2. They saved and published the new blueprint without any problem, then they tried to deploy the new blueprint. The blueprint deployment kept failing with the following error:

“Request failed: Machine VTTestVM001: Timeout customizing machine”

From the error, I was able to tell it was getting stuck at the guest customization stage, so I deployed one more VM and waited till it get to the guest customization stage, then opened a console to the VM to be greeted  with the following Sysprep error:

Windows could not parse or process the unattend answer file for pass [specialize]. The settings specified in the answer file cannot be applied. The error was detected while processing settings for component [Microsoft-Windows-Shell-Setup]”

Below is a screenshot showing the actual error on screen:

Windows could not parse or process the unattend answer file or pass [specialize]

After I hit OK, the machine restarted again and gave the following error and kept repetitively restarting and giving the same error afterword:

“The computer restarted unexpectedly or encountered an unexpected error. Windows installation cannot proceed. To install Windows, click “OK” to restart the computer, and then restart the installation”

Below is a screenshot of the actual error on screen:

The computer restarted unexpectedly or encountered an unexpected error

From the errors above it was obvious to me it is a sysprep problem and got nothing to do with vCAC, so I tried to do the same deployment through vCenter using the deploy from template option and I have got the same error and I figured out it was a sysprep issue. I asked the customer what kind of changes did they have between the two templates, and I was told the previous one was 2012 and this one is 2008 R2. While it seems the Custom Specs does not need to change as both of them is Windows, they forgot to change the Windows Key in the Customization Spec. Changing that has fixed the problem and deployment went right through.

Further, it seems VMware has a KB article that document this issue: KB2008221, where it provide more info on the cause as below:

This issue occurs when a virtual machine with a licensed version of Windows Server 2008, Windows 2008 R2, Windows 2012, or Windows Vista is cloned using the Customization Wizard and an invalid Product ID is entered in the Windows License page, cloned virtual machines reboot repeatedly with errors.

This issue occurs because Virtual Machine Manager (VMM) can only validate the syntax of the product key. However, it cannot validate whether or not the key is valid for that OS. If you create a guest OS profile with a syntactically valid product key but invalid for the OS which is being deployed, you will get an error during customization.

As for a resolution, as I mentioned all you had to do is provide a valid key for the particular OS type you are using in the Customization Specification, and Viola you should be on your way!


  1. How about a tutorial or a clear and detailed pathway to achieve this process…As I have a windows 7 sp1 and tried to partition if into 2 but KEEP GETTING stuck in this error message……This did not happen previous to windows 10?
    thank you in advance

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