Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/aptdaemon/gtkwidgets.py", line 433, in _on_clicked
    transaction.cancel()
  File "/usr/lib/python2.6/dist-packages/aptdaemon/defer.py", line 510, in _deferable
    return func(*args, **kwargs)
  File "/usr/lib/python2.6/dist-packages/aptdaemon/errors.py", line 151, in _convert_dbus_exception
    raise get_native_exception(error)
AptDaemonError: org.debian.apt: Could not cancel transaction