The Graphical User Interface Method for Upgrading Oracle Database
Database Upgrade Assistant (DBUA) interactively steps you through the upgrade process and configures the database for the new Oracle Database release.
DBUA starts the Pre-Upgrade Information Tool, which fixes some configuration settings to the values required for the upgrade. For example, the tool can change initialization parameters to values required for the upgrade. The tool also provides you with a list of items that you can fix manually before you continue with the upgrade.
Parent topic: Preparing to Upgrade Oracle Database