Hi, are we able to backup DB from 4.0.2 and then restore it in a fresh 4.0.3 installation? Would the system automatically make the adjustments to make it work with 4.0.3? thanks
You could, but if any of the database schema is different, you'll end up in trouble.
What problem(s) are you trying to avoid by upgrading this way? Backup in 4.0.2, use the Upgrade Center to upgrade to 4.0.3, if there are any issues, use the restore link which is generated at the end of the 4.0.3 upgrade to revert back to 4.0.2.
Bad idea to assume DB schemas are compatible.