Comment 7 for bug 801696

I have the same problem.

$sudo update-manager -c -d
extracting 'oneiric.tar.gz'
authenticate 'oneiric.tar.gz' against 'oneiric.tar.gz.gpg'
apport start/running
Traceback (most recent call last):
  File "/tmp/update-manager-9PPri4/oneiric", line 7, in <module>
    sys.exit(main())
  File "/tmp/update-manager-9PPri4/DistUpgradeMain.py", line 202, in main
    if app.run():
  File "/tmp/update-manager-9PPri4/DistUpgradeController.py", line 1642, in run
    return self.fullUpgrade()
  File "/tmp/update-manager-9PPri4/DistUpgradeController.py", line 1612, in fullUpgrade
    if not self.doDistUpgrade():
  File "/tmp/update-manager-9PPri4/DistUpgradeController.py", line 1006, in doDistUpgrade
    self._maybe_create_apt_btrfs_snapshot()
  File "/tmp/update-manager-9PPri4/DistUpgradeController.py", line 990, in _maybe_create_apt_btrfs_snapshot
    res = apt_btrfs.create_btrfs_root_snapshot(prefix)
  File "/tmp/update-manager-9PPri4/apt_btrfs_snapshot.py", line 122, in create_btrfs_root_snapshot
    os.path.join(mp, self.SNAP_PREFIX+additional_prefix+snap_id))
  File "/tmp/update-manager-9PPri4/apt_btrfs_snapshot.py", line 69, in btrfs_subvolume_snapshot
    source, dest])
  File "/usr/lib/python2.7/subprocess.py", line 486, in call
    return Popen(*popenargs, **kwargs).wait()
  File "/usr/lib/python2.7/subprocess.py", line 672, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1213, in _execute_child
    raise child_exception
OSError: [Errno 2] 没有那个文件或目录