Since the release of Oracle Database 11g, it has reinforced security by default. This should in principle be positive, but there are some situations where some behaviors may be unpleasant.
The most obvious example can be found in the modification of the profile (PROFILE) DEFAULT, which is applied to any user created by default.
In previous versions, the DEFAULT profile does not include any reference to password expiration, this has changed. From 11g a caducity of 180 days passwords applies. This is something that can give you a shock, because you find the problem six months later having performed the installation (and not surprisingly takes some time to get in situation).
To avoid surprises we can run:
ALTER PROFILE "DEFAULT" LIMIT PASSWORD_GRACE_TIME UNLIMITED; ALTER PROFILE "DEFAULT" LIMIT PASSWORD_LIFE_TIME UNLIMITED;
In this way we eliminate the expiration of passwords.