Wrong number or types of arguments in call to even after correct parameters

Question

I have spent plenty of my time investigating about this issue, even I have found few similar posts on this site but not useful.

If someone can help me.

Below is the Exception:

ORA-06550: line 1, column 7:
PLS-00306: wrong number or types of arguments in call to 'AUTOPROVGETUSERGROUPS'
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored

C# code:

public static List<CHPGroupishObject> ConnectThirdPartyOracleDBForData(string connectionstring, string SPName, string Filter, string Param2, string Param3, string Param4)
    {
        DataSet result;
        List<CHPGroupishObject> lstCHPGroupishObject = new List<CHPGroupishObject>();
        CHPGroupishObject cHPGroupishObject = null;
        try
        {
            DbMain objDbHandler = new DbMain(connectionstring);
            RetResult resultObject = new RetResult();
            ArrayList colParams = new ArrayList();
            OracleParameter param = new OracleParameter("Filter", OracleType.VarChar, 300, ParameterDirection.Input, "", DataRowVersion.Default, true, Filter);
            colParams.Add(param);
            param = new OracleParameter("Param2", OracleType.VarChar, 300, ParameterDirection.Input, "", DataRowVersion.Default, true, Param2);
            colParams.Add(param);
            param = new OracleParameter("Param3", OracleType.VarChar, 300, ParameterDirection.Input, "", DataRowVersion.Default, true, Param3);
            colParams.Add(param);
            param = new OracleParameter("Param4", OracleType.VarChar, 300, ParameterDirection.Input, "", DataRowVersion.Default, true, Param4);
            colParams.Add(param);
            param = new OracleParameter("RefCursor", OracleType.Cursor, 4000, ParameterDirection.Output, "", DataRowVersion.Default, true, null);
            colParams.Add(param);
            result = objDbHandler.ExecuteProcedure(SPName, "GARSAccount", ref colParams);
            foreach (DataRow row in result.Tables[0].Rows)
            {
                cHPGroupishObject = new CHPGroupishObject();
                cHPGroupishObject.dn = row["EntitlementCode"].ToString();
                cHPGroupishObject.Name = row["EntitlementName"].ToString();
                lstCHPGroupishObject.Add(cHPGroupishObject);
            }
            return lstCHPGroupishObject;
        }
        catch (Exception ex)
        {
            return null;
        }
    }

Oracle Stored Procedure:

CREATE OR REPLACE PROCEDURE AEP_SYSTEMATIC.AUTOPROVGETUSERGROUPS(
          Filter IN VARCHAR,  -- Clone id.  Pass null unless Param2 is 'Clone from user'
          Param2 IN VARCHAR,  -- MyAccess profile
    Param3 IN VARCHAR,
    Param4 IN VARCHAR,
          RefCursor OUT SYS_REFCURSOR)
AS
    cloneUser varchar(200);
    num_users number;
    sqlErr varchar2(4000);
begin
    if (Filter is null or Filter = '') then
        insert into AEP_SYSTEMATIC.AUTOPROVLOG(MESSAGETYPE, MESSAGE, USERNAME)
        values ('INFO', 'GetUserGroups requested with blank clone user', 'MyAccess');
        commit;
        open RefCursor for
        select 'FAIL' as Result, 'No clone user provided' as Message from dual;
        return;
    end if;
    cloneUser := trim(Filter);
    insert into AEP_SYSTEMATIC.AUTOPROVLOG(MESSAGETYPE, MESSAGE, USERNAME)
        values ('INFO', 'Getting user groups for ' || cloneUser || ' ' || Param2, cloneUser);
    commit;
    select count(USER_NAME) into num_users from AEP_SYSTEMATIC.DRC_USERS where USER_NAME = cloneUser;
        if (num_users = 0) then
        insert into AEP_SYSTEMATIC.AUTOPROVLOG(MESSAGETYPE, MESSAGE, USERNAME)
            values ('ERROR', 'Failed to find USER_NAME for user ' || cloneUser, cloneUser);
        commit;
        open RefCursor for
        select 'FAIL' as Result, 'Failed to find USER_NAME for user ' || cloneUser as Message from dual;
        return;
          else
        OPEN RefCursor FOR
        select distinct '[UserGroup:' || u.RIGHTS || ']' as EntitlementCode,
        u.RIGHTS || ' - ' || ug.DESCRIPTION as EntitlementName
        from AEP_SYSTEMATIC.DRC_USERS u, AEP_SYSTEMATIC.DRC_USER_GROUPS ug
        where
        (
            cloneUser is null or not cloneUser is null and RIGHTS in
            (select RIGHTS from AEP_SYSTEMATIC.DRC_USERS where USER_NAME = cloneUser)
        )
        and u.RIGHTS = ug.USER_GROUP;
    end if;
    exception when others then
        sqlErr := sqlerrm;
        insert into AEP_SYSTEMATIC.AUTOPROVLOG(MESSAGETYPE, MESSAGE, USERNAME)
        values('ERROR', substr(sqlErr, 1, 1800), cloneUser);
        commit;
        open RefCursor for
        select 'FAIL' as Result, 'Error in AutoProvGetUserGroups: ' || substr(sqlErr, 1, 500) as Message from dual;
end AUTOPROVGETUSERGROUPS;
/
GRANT EXECUTE ON AEP_SYSTEMATIC.AUTOPROVGETUSERGROUPS TO AEP_SYSTEMATIC_RO_ROLE
/

Answer 1

ok got my answer!!

String is nullable type and SQL server accepts if we pass null string to it but Oracle doesn't.

Here, Param2 was passing null and because of that it was giving an error.