An error occurs when inserting because the to_date value in the was client and the to_date value in

Moving to Oracle Cloud

DB changed from 11g to 19c

WAS is changing from Windows to Linux.

However, there is a problem with SQL, which used to work well.

The reason is

SELECT TO_DATE('2021/09/16', 'YY/MM/DD') FROM DUAL

is executed in WAS, the result is RETURN to '16-SEP-21' and LENGTH error occurs.

Is there any way to solve this?

I want to solve it permanently, not temporarily with ALTER SESSION SET NLS_DATE_FORMAT.