vboxmanage closemedium disk broken: "The object is not ready", worked in 3.x

[VirtualBoxBug]

VBoxManage closemedium disk deleteme.vdi --delete

gives

VBoxManage.exe: error: The object is not ready
VBoxManage.exe: error: Details: code E_ACCESSDENIED (0x80070005),
  component Medium, interface IMedium, callee IUnknown
Context: "FindMedium(Bstr(pszFilenameOrUuid).raw(), enmDevType,
  pMedium.asOutParam())" at line 174 of file VBoxManageDisk.cpp

The same result with full path to the vdi or without the extension; in fact whatever I write as the disk name I get the same error. It worked in 3.x and the vdi can be removed using the GUI. I can't use --delete when unregistering the VM because I want to keep the OS disk.

MAYBE RELATED:

some other guy at ​http://daniel.hepper.net/blog/ got

$ VBoxManage list vms
"" {b68ed7a7-6e72-4f16-a438-8775cd80d9b3}
$ VBoxManage unregistervm {b68ed7a7-6e72-4f16-a438-8775cd80d9b3} --delete
VBoxManage: error: The object is not ready
VBoxManage: error: Details: code E_ACCESSDENIED (0x80070005),
  component Machine, interface IMachine, callee nsISupports
Context: "Delete(ComSafeArrayAsInParam(aMedia),
  pProgress.asOutParam())" at line 175 of file VBoxManageMisc.cpp
Segmentation fault

some other guy at ​http://forums.virtualbox.org/viewtopic.php?f=7&t=38150

Simply unregistering the machine without detaching the drives first seems to work, however unregistering the machine with the '--delete' flag gives:

Code: Select all   Expand viewCollapse view
    VBoxManage: error: The object is not ready
    VBoxManage: error: Details: code E_ACCESSDENIED (0x80070005),
  component Machine, interface IMachine, callee nsISupports
    Context: "Delete(ComSafeArrayAsInParam(aMedia),
  pProgress.asOutParam())" at line 167 of file VBoxManageMisc.cpp
    Segmentation fault (core dumped)

[aeichner]

Please reopen if still relevant with a recent VirtualBox release.