operation canceled

  Explanation:  The lock conversion request has been canceled, and
  the lock has been granted at its previous lock mode.  This
  condition value is returned under the following conditions:  a
  lock request results in queueing a lock conversion request, the
  request has not been granted yet (it is in the conversion
  queue), and, in the interim, the unlock service is called to
  cancel this lock conversion.  Note that if the waiting
  conversion request is granted BEFORE the unlock call can cancel
  the conversion, the unlock call returns CANCELGRANT, and the
  conversion request returns NORMAL.

  User Action:  This error message indicates a possible error in
  the locking protocols.  Contact your Oracle support
  representative for assistance.