verification of constraints is incomplete due to errors.

  Explanation:  An  error  occurred  during  the  verification  of
  constraints which prevented further verification of constraints.
  Other  requested   verifications   were   performed.    Messages
  describing  the error that prevented constraint verification are
  displayed following this message.

  User  Action:   If  the  messages  following  this  message  are
  LOCK_CONFLICT  followed  by  CANTSNAP,  then there was a locking
  conflict between the transaction verifying the constraint (which
  is a read-only transaction) and another transaction which has an
  area  locked  in   exclusive   mode.    Retry   the   constraint
  verification when no exclusive transactions are running.