Oracle recommends that you complete these good practices guidelines for updating Oracle Database. Except where noted, these practices are recommended for all types of upgrades.

• Back Up the Database
  Oracle strongly recommends that you at least perform a level 1 backup, or if time allows, perform a level 0 backup.
• Upgrading Statistics Tables Created by the DBMS_STATS Package After Upgrading Oracle Database
  If you created statistics tables using the DBMS_STATS.CREATE_STAT_TABLE procedure, then upgrade these tables by running DBMS_STATS.UPGRADE_STAT_TABLE.
• Regathering Fixed Objects Statistics with DBMS_STATS
  After an upgrade, or after other database configuration changes, Oracle strongly recommends that you regather fixed object statistics after you have run representative workloads on Oracle Database.
• Dropping and Recreating DBMS_SCHEDULER Jobs
  If DBMS_SCHEDULER jobs do not function after upgrading from an earlier release, drop and recreate the jobs.
• Transfer Unified Audit Records After the Upgrade
  Review these topics to understand how you can obtain better performance after you upgrade and migrate to unified auditing
• Enabling Disabled Release Update Bug Fixes in the Upgraded Database
  Because bug fixes in Release Updates that can cause execution plan changes are disabled, Oracle recommends that you enable the disabled bug fixes that you want to use.
• Reset Passwords to Enforce Case-Sensitivity
  For upgraded databases, improve security by using case-sensitive passwords for default user accounts and user accounts.
• Configuring the FTP and HTTP Ports and HTTP Authentication for Oracle XML DB
  Oracle Database Configuration Assistant (DBCA) does not configure ports for Oracle XML DB on Oracle Database 12c and later releases. Upgrades use digest authentication.
• Add New Features as Appropriate
  Review new features as part of your database upgrade plan.
• Develop New Administrative Procedures as Needed
  Plan a review of your scripts and procedures, and change as needed.
• Migrate Your Upgraded Oracle Databases to Use Unified Auditing
  Traditional auditing is deprecated. To use the full facilities of unified auditing, you must manually migrate to unified auditing.
• Migrating From Rollback Segments To Automatic Undo Mode
  If your database release is earlier than Oracle Database 11g, then you must migrate the database that is being upgraded from using rollback segments (manual undo management) to automatic undo management.
• Migrating Tables from the LONG Data Type to the LOB Data Type
  You can use the ALTER TABLE statement to change the data type of a LONG column to CLOB and that of a LONG RAW column to BLOB.
• Identify Oracle Text Indexes for Rebuilds
  You can run a script that helps you to identify Oracle Text index indexes with token tables that can benefit by being rebuilt after upgrading to the new Oracle Database release..
• About Testing the Upgraded Production Oracle Database
  Repeat tests on your production database that you carried out on your test database to ensure applications operate as expected.
• Upgrading the Time Zone File Version After Upgrading Oracle Database
  If the AutoUpgrade preupgrade report instructs you to upgrade the time zone files after completing the database upgrade, and you do not set AutoUpgrade to complete this task for you, then use any of the supported methods to upgrade the time zone file.