VirtualBox Cannot register the hard disk already exists

I created a virtual disk file VM_1_Ubuntu.vdi. Then I moved it into another folder. I tried to update VM settings (right click on virtual machine -> settings -> Storage -> Controller SATA tab, VM_1_Ubuntu.vdi path). I wanted to set a new path.

It says Cannot register the hard disk already exists

I found a solution

File -> Virtual Media Manager -> Removed existing images (note, I removed them only from the registry).

I followed these steps.

http://www.webdesignblog.asia/software/virtualbox-moving-vdi-file-re-linking-guest/#sthash.1QOHeiw5.dpbs

After that I could update the path in the VM settings.

It's possible to change the UUID on the VDI file using the command:

 VBoxManage internalcommands sethduuid <file.vdi>

It seems this command assigns a new "random" UUID to the file. No much documentation on it, though.

1. Select File from Oracle VM VirtualBox Manager
2. Virtual Media Manager
3. Remove the file (highlighted yellow) from Hard disks tab.

Here is the solution for that find the UUID of box

vboxmanage list hdds

then delete by

vboxmanage closemedium disk <uuid> --delete

If there is no possibility to remove or change path to a hard disc file using Virtual Media Manager (in my case) then:

1. Open '.vbox' and '.vbox-prev' (if exist) files in any text editor.
2. Edit 'location' attribute of the element 'HardDisk' to your path, for example: "d:/VM/VirtualBox/Win10/Win10.vmdk" (screenshot).

In some cases first your need to Release, then Remove and Re-add via Virtual Media Manager

I really appreciate the suggestions here. The Impaler's and Oleg's comments helped me to piece my solution together.

Use the VBoxManage CLI. There's a modifymedium command with a --setlocation option.

I suggest opening the VBox GUI (on VM VirtualBox Manager 6.0)

• select "Virtual Media Manager" (I used the File menu)
• select the "Information" button for the disk giving you this error
• copy the UUID
  Note: I removed the controller from the "Storage" setting before the next step.
• open your command prompt and navigate to the location of the .vdi file
  It's a good idea to type VBoxMange to see a list of options, but this is the command to run:

VBoxManage modifymedium [insert medium type here] [UUID] --setlocation [full path to .vdi file]

Finally, reattach the controller to any VM--preferably the one you'd like to fix.

1 - Open the files '.vbox' and '.vbox-prev' (if exist) files in any text editor and replace the first character of HardDisk uuid (take note to revert this change on step 6)

Example: nano /home/virtualbox/WindowsServer/WindowsServer.vbox

Change:

<HardDisks>
        <HardDisk uuid="{3ebaa9b6-8318-4b81-b853-8f30dd278bdc}" location="/home/virtualbox/WindowsServer/WindowsServer.vdi" format="VDI" type="Normal"/>

To:

<HardDisks>
        <HardDisk uuid="{2ebaa9b6-8318-4b81-b853-8f30dd278bdc}" location="/home/virtualbox/WindowsServer/WindowsServer.vdi" format="VDI" type="Normal"/>

2 - Reboot machine

4 - Stop Virtual Machine (if started)

5 - On terminal:

su vbox
cd /home/virtualbox/WindowsServer/
VBoxManage modifyhd WindowsServer.vdi --resize SIZE
exit
exit

change SIZE for a number in Megabytes, example 80000 (80GB)

6 - Open again the files '.vbox' and '.vbox-prev' (if exist) files in any text editor and replace the first character of HardDisk uuid whith the original value

Example: nano /home/virtualbox/WindowsServer/WindowsServer.vbox

Change:

<HardDisks>
        <HardDisk uuid="{2ebaa9b6-8318-4b81-b853-8f30dd278bdc}" location="/home/virtualbox/WindowsServer/WindowsServer.vdi" format="VDI" type="Normal"/>

To:

<HardDisks>
        <HardDisk uuid="{3ebaa9b6-8318-4b81-b853-8f30dd278bdc}" location="/home/virtualbox/WindowsServer/WindowsServer.vdi" format="VDI" type="Normal"/>

7 - Reboot machine

The solution that worked for me is as follows:

1. Make sure VirtualBox Manager is not running.
2. Back up the files ~\.VirtualBox\VirtualBox.xml and ~\.VirtualBox\VirtualBox.xml-prev.
3. Edit these files to modify the <HardDisks>...</HardDisks> section to remove the duplicate entry of <HardDisk />.
4. Now run VirtualBox Manager.

Example:

  <HardDisks>
    <HardDisk uuid="{38f266bd-0959-4caf-a0de-27ac9d52e3663}" location="~/VirtualBox VMs/VM1/box-disk001.vmdk" format="VMDK" type="Normal"/>
    <HardDisk uuid="{a6708d79-7393-4d96-89da-2539f75c5465e}" location="~/VirtualBox VMs/VM2/box-disk001.vmdk" format="VMDK" type="Normal"/>
	<HardDisk uuid="{bdce5d4e-9a1c-4f57-acfd-e2acfc8920552}" location="~/VirtualBox VMs/VM2/box-disk001.vmdk" format="VMDK" type="Normal"/>
  </HardDisks>

Note in the above fragment that the last two entries refer to the same VM but have different uuid's. One of them is invalid and should be removed. Which one is invalid can be found out by hit and trial -- first remove the second entry and try; if it doesn't work, remove the third entry.

After struggling for many days finally found a solution that works perfectly.

Mac OS open ~/Library folder (in your home directory) and delete the VirtulBox folder. This will remove all configurations and you can start the virtual box again!

Others look for .virtualbox folder in your home directory. Remove it and open VirtualBox should solve your issue.

Cheers!!