error: can't be used as the requested device type

[neuronetv]

VBoxManage: error: The medium '/root/VirtualBox VMs/<vm> can't be used as the requested device type.
I previously had my vm as a vmdk and I converted it to vdi with this command:

VBoxManage clonehd --format VDI centos6-disk1.vmdk centos6-disk1.vdi

after which I had a vdi file as well as a vmdk file in my vm folder. Is this the way it's supposed to work? This is the first time I've ever tried to convert a vmdk so I don't know what to expect.
I then booted the vm and ran zerofree in it to prepare for the compact. However when I ran the compact command it throws the error. The console doesn't give any reason for this error, this is the full output:

# VBoxManage modifyhd "centos6" --compact
VBoxManage: error: The medium '/root/VirtualBox VMs/centos6' can't be used as the requested device type
VBoxManage: error: Details: code NS_ERROR_FAILURE (0x80004005), component Medium, interface IMedium, callee nsISupports
VBoxManage: error: Context: "OpenMedium(Bstr(pszFilenameOrUuid).raw(), enmDevType, enmAccessMode, fForceNewUuidOnOpen, pMedium.asOutParam())" at line 178 of file VBoxManageDisk.cpp

What's the solution to this?

[Perryg]

What's the solution to this?

Stop using root.

[neuronetv]

thaniks but that didn't work. I stopped using root and changed to a user and I still get:

-sh-3.2$ VBoxManage modifyhd "centos6" --compact
VBoxManage: error: The medium '/home/<user>/VirtualBox VMs/centos6' can't be used as the requested device type
VBoxManage: error: Details: code NS_ERROR_FAILURE (0x80004005), component Medium, interface IMedium, callee nsISupports
VBoxManage: error: Context: "OpenMedium(Bstr(pszFilenameOrUuid).raw(), enmDevType, enmAccessMode, fForceNewUuidOnOpen, pMedium.asOutParam())" at line 178 of file VBoxManageDisk.cpp

update; I've just noticed in the above error message that vboxmanage is trying to go to '/VirtualBox VMs/centos6' but the correct path is /VirtualBox\ VMs/centos6, I don't know how to tell vbox that there should be a reverse slash at the end of 'VirtualBox'.

[Perryg]

You need to provide the absolute path to the file and include the file name and extension. Put quotes around the path if there are spaces.