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Editing a virtual machine with a duplicate UUID.bios (1002403)

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  • When you convert a virtual machine using VMware converter or when you clone a virtual machine (not a template), the new virtual machine does not have a unique UUID.bios
  • You may see an error similar to:

    msg:disk.duplicateUUID:Virtual disk. Virtual Disks with same UUID should not be assigned to a VM since this can lead problems when the guest boots. Please make sure virtual disks have unique UUIDs


You cannot run virtual machines with the same UUID. When you clone or convert virtual machines, sometimes they end up with the same UUID. When this happens you must change the UUIDs so each virtual machine’s UUID is unique.

You can change the UUIDs:

  • Programmatically (recommended)
  • Manually (not recommended)

To change the UUIDs programmatically you need the following items on the Windows host machine for the virtual machine:

Programmatically changing the UUID of a virtual machine

To programmatically change the UUID:
  1. Install VI Perl Toolkit.

  2. Power off the virtual machine.

  1. Download the script,, attached to this article, to the VI Perl directory /samples/vm.

    The Perl Toolkit installer creates the directory /samples/vm. Put the script into the VI Perl Toolkit /samples/vm directory.

  1. Launch a Windows Console session.

  2. From Windows, click Start > Run, type cmd.exe, and click OK

  3. Launch the UUID script.

From the command prompt:

o        Change to the \viperltoolkit\Perl\samples\vm directory.

o        Run the command:

C:\viperltoolkit\Perl\samples\vm > perl --url https://%3chost%3e:%3cport%3e/sdk/vimService --username <myuser> --password <mypassword> --vmname <VirtualMachineName> --uuid <UUID>



<host> is the name of the server where the virtual machine resides.

<port> is an access port on the server where the virtual machine resides.

<myuser> is your administrator privilege level user name.

<mypassword> is your corresponding user name’s password.

<VirtualMachineName> is the name of the virtual machine whose UUID you are changing.

<UUID> is the new UUID value for the virtual machine.

Manually changing the UUID of a virtual machine

To manually change the UUID:
Note: This method is not recommended. If possible, use the UUIDScript.plto change duplicated UUID numbers.
  1. Power off the virtual machine whose UUID you are going to change.
  2. Edit the virtual machine’s configuration file (.vmx ). Use a text editor of your choice.
  3. Search the file for the line:

    uuid.bios = <uuidvalue>

  4. Enter the new UUID in this format. Include the quotation marks.

    uuid.bios = "00 11 22 33 44 55 66 77-88 99 aa bb cc dd ee ff"

    The UUID is a 128-bit integer. The 16 bytes of this value are created by using 16 hexadecimal digit pairs. Each digit in the pair can have any value between 0 to f (the digits of the hexadecimal number system), for example 1e, 87 or d3. These pairs are separated by spaces, except for a dash between the eighth and ninth hexadecimal pairs. The UUID is generally based on the physical computer's identifier and the path to the virtual machine's configuration file.

  5. Save and close the configuration file.
  6. Power on the virtual machine.

    The new UUID is used when the virtual machine boots.

Additional Information

For translated versions of this article, see: 


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