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The error occurs if the partition type is GUID Partition Table (GPT), which is not supported by FDE.

To check if the disk uses GPT:

  1. Open the command prompt as an administrator and type the following commands:

    1. diskpart
    2. list disk

    You will see a (**) symbol below GPT.

  2. Use a third party software to convert GPT to MBR format. For example, the Partition Tool.
 
Do a test on a less critical machine before applying the steps on other machines. Ensure to have a backup before changing the partition type.