Message Oracle ORA-34731 - (NLSSORT01) number is not a valid NLS_SORT specification.

ERROR(NLSSORT01) number is not a valid NLS_SORT specification.
CAUSEAn unrecognized NLS_SORT value was specified in the SORT command or the SORT, SORTLINES or UNIQUELINES function.
ACTIONSpecify a supported NLS_SORT value.