diff --git a/gns3server/modules/virtualbox/__init__.py b/gns3server/modules/virtualbox/__init__.py
index 04df958f..24f2f684 100644
--- a/gns3server/modules/virtualbox/__init__.py
+++ b/gns3server/modules/virtualbox/__init__.py
@@ -110,7 +110,6 @@ class VirtualBox(BaseManager):
                 raise VirtualBoxError("VBoxManage has timed out after {} seconds!".format(timeout))
 
             if process.returncode:
-                # only the first line of the output is useful
                 vboxmanage_error = stderr_data.decode("utf-8", errors="ignore")
                 raise VirtualBoxError("VirtualBox has returned an error: {}".format(vboxmanage_error))
 
diff --git a/gns3server/modules/virtualbox/virtualbox_vm.py b/gns3server/modules/virtualbox/virtualbox_vm.py
index ed1580ab..e0a181be 100644
--- a/gns3server/modules/virtualbox/virtualbox_vm.py
+++ b/gns3server/modules/virtualbox/virtualbox_vm.py
@@ -321,6 +321,7 @@ class VirtualBoxVM(BaseVM):
 
         if self._linked_clone:
             hdd_table = []
+            hdd_files_to_close = []
             if os.path.exists(self.working_dir):
                 hdd_files = yield from self._get_all_hdd_files()
                 vm_info = yield from self._get_vm_info()
@@ -331,6 +332,7 @@ class VirtualBoxVM(BaseVM):
                         port = match.group(2)
                         device = match.group(3)
                         if value in hdd_files:
+                            hdd_files_to_close.append(value)
                             log.info("VirtualBox VM '{name}' [{id}] detaching HDD {controller} {port} {device}".format(name=self.name,
                                                                                                                        id=self.id,
                                                                                                                        controller=controller,
@@ -351,6 +353,12 @@ class VirtualBoxVM(BaseVM):
             log.info("VirtualBox VM '{name}' [{id}] unregistering".format(name=self.name, id=self.id))
             yield from self.manager.execute("unregistervm", [self._name])
 
+            for hdd_file in hdd_files_to_close:
+                log.info("VirtualBox VM '{name}' [{id}] closing disk {disk}".format(name=self.name,
+                                                                                    id=self.id,
+                                                                                    disk=os.path.basename(hdd_file)))
+                yield from self.manager.execute("closemedium", ["disk", hdd_file])
+
             if hdd_table:
                 try:
                     hdd_info_file = os.path.join(self.working_dir, self._vmname, "hdd_info.json")