Signature Collision” for GPT Disk

Question

Signature Collision” for GPT Disk,Virtual Disk Service error:

The operation is not allowed on a disk that is offline.

Answer 1

Hello,

You are seeing this because Windows kept the disk offline after detecting a duplicate disk identifier. The fix is to give that GPT disk a new Unique ID with DiskPart, then bring it online. This does not touch the data.

Run these steps in an elevated PowerShell or Command Prompt.

First generate a fresh GUID to use as the new disk ID. In PowerShell run:

[guid]::NewGuid().Guid

Copy the value you get, for example 3f4a0b0d-5f6e-4f1d-8a53-2a9f8e33b3c1. Start DiskPart and identify the problem disk:

diskpart
list disk
select disk <number>
detail disk

Confirm you selected the right disk by checking size and the line that says The disk is offline because it has a signature collision.

Assign a new Unique ID, then bring the disk online. If the disk is GPT, set the GUID you generated, including braces:

uniqueid disk id={3f4a0b0d-5f6e-4f1d-8a53-2a9f8e33b3c1}
online disk

If DiskPart shows the disk is MBR instead of GPT, set an 8-digit hex ID instead, for example:

uniqueid disk id=AB12CD34
online disk

If the volume does not appear in File Explorer, assign a letter:

list volume
select volume <number>
assign letter=<choose one>
exit

That's it. The collision happened because the disk was cloned or imaged from another disk, so both had the same identifier. Giving it a new one lets Windows bring it online and clears the Virtual Disk Service error.

If any command fails, paste the exact DiskPart output and I will adjust the next step.