RE: ORA-12801: error signaled in parallel query server P038 ORA-12801: error signaled in parallel query server P038
Did you try it serially?
I've usually seen these types of errors with corruption.
Try analyze table table_name validate structure.
Or run a query that does a full table scan and see if you get the same
Select /*+ full(a) */ count(*)
From table_name a;