In this how to guide, we will see how we can fix the UUID already exist error in Oracle VirtualBox. You may get this error “Cannot register the hard disk ‘E:\VM\WinXP.vhd’ {f638de02-59bc-4d57-b2f9-4caaa7ef7d25} because a hard disk ‘F:\WinXP.vhd’ with UUID {f638de02-59bc-4d57-b2f9-4caaa7ef7d25} already exists.” when you are adding a pre-existing virtual hard disk (.vhd) to a new VirtualBox machine.

This error typically comes when you are creating a new VM using pre-existing VHD or attaching a VHD to a VM.

There is very simple fix for this error, just simply change the UUID of the virtual hard disk. We can do this from command line.

First open virtual box location in command line. Open command line and to go to VirtualBox installation location type:

cd "C:\Program Files\Oracle\VirtualBox"

After this to change the UUID of your hard disk, type this command:

VBoxManage internalcommands sethduuid <location_of_your_VHD_file>

For example, here I am changing the UUID of my VHD file:

Simple fix. If you have any questions, please let me know via comments.