Got disconnect from DB whenever query a view

Dear Oracle folks,

I got disconnect from DB error message (ORA-03113: end-of-fie on communication channel) whenever I query a view like below

select * from valid_contract where contract_id in ('E1539','E2630','E2332');

Pass which contract_id in the where clause doesn't matter, but number of contract_id passed does matter, it always fails at 3. It means:

1) where contract_id in ('E1539','E2630','E2332')  --- error out

2) where contract_id in ('E1539','E2630') ---no error

3) where contract_id in (('E1539','E2630','E2332', 'E1111',...more id) ---no error

The structure of the view has two union parts (A union