Master Boot Record Disks Cannot Be Converted to GPT by Means of an Unattended Setup

When you use the following line of code in an unattended answer file, a master boot record (MBR) disk cannot be converted to a GUID partition table (GPT) disk (where GUID is the abbreviation for globally unique identifier):

This behavior can occur because the preceding line of code can only convert raw disks to GPT disks.

To work around this behavior, either make the disk raw or create the GPT disk before you run the unattended Setup. You can use the Diskpart.efi utility to make the disk either raw or GPT.

This behavior is by design.

For more information about the creation of an unattended Setup answer file, refer to the Windows XP Resource Kit.