ORA-01489: result of string concatenation is too long

 SELECT '' ID,

        RP.GRANTEE AS USERNAME,
        LISTAGG (rp.granted_role || '-' || D.Name || '-' || P.NAME, ',') WITHIN GROUP (ORDER BY grantee) As ROLES_MEMBERSHIP,
        U.ACCOUNT_STATUS AS STATUS
     FROM CDB_ROLE_PRIVS RP,
          V$DATABASE D,
          V$PDBS P,
          CDB_USERS U
    WHERE RP.CON_ID = P.CON_ID
          AND RP.GRANTEE(+) = U.USERNAME
          AND U.CON_ID = P.CON_ID
          AND U.CON_ID >= 3
 GROUP BY RP.GRANTEE,
          U.ACCOUNT_STATUS
  
  
 ORA-12801: error signaled in parallel query server P007
 ORA-01489: result of string concatenation is too long       

This error message is almost auto-explicative, it is because the the return of listagg function is Varchar and it has a limit of 4000 characters.

From 12.2 onwards you can use, if it is applicable for your case, the parameter to truncate the results with the clause ON OVERFLOW TRUNCATE, for our usage this solution can’t be applied, because we need to deliver the whole data to auditor requested. Just an example how to use it.

LISTAGG(NameOfYourColunm, ‘,’ ON OVERFLOW TRUNCATE)

 SELECT '' ID,
        RP.GRANTEE AS USERNAME,
        LISTAGG (rp.granted_role || '-' || D.Name || '-' || P.NAME, ',' ON OVERFLOW TRUNCATE) WITHIN GROUP (ORDER BY grantee) As ROLES_MEMBERSHIP,
        U.ACCOUNT_STATUS AS STATUS
     FROM CDB_ROLE_PRIVS RP,
          V$DATABASE D,
          V$PDBS P,
          CDB_USERS U
    WHERE RP.CON_ID = P.CON_ID
          AND RP.GRANTEE(+) = U.USERNAME
          AND U.CON_ID = P.CON_ID
          AND U.CON_ID >= 3
 GROUP BY RP.GRANTEE,
          U.ACCOUNT_STATUS  
          U.ACCOUNT_STATUS;