Be aware of these guidelines as a best practice before you perform an upgrade.
If you have an existing Oracle Database installation, then do the following:
Record the version numbers, patches, and other configuration information
Review upgrade procedures for your existing installation
Review Oracle Database upgrade documentation before proceeding with installation, to decide how you want to proceed
Always create a backup of existing databases before starting any configuration change.
Refer to Oracle Database Upgrade Guide for more information about required software updates, pre-upgrade tasks, post-upgrade tasks, compatibility, and interoperability between different releases.