What about ...

SELECT * from (
SELECT * from newerror ;
union;
select * from olderror ;
) AllError outer join htc in AllError.id = htc.id


If this doesn´t work try ....


SELECT * from (
SELECT * from newerror ;
union;
select * from olderror ;
) AllError join htc in AllError.id <> htc.id


Greetings
Nuno Brito