To take full advantage of new features, you must upgrade applications running in the new release.

Many new features and enhancements are available after upgrading to a new release of Oracle Database. Review these topics for guidance in planning these application upgrades.

• Overview of Upgrading Applications on a New Oracle Database Release
  You are not required to modify existing applications that do not use features available in the new Oracle Database release.
• Compatibility Issues for Applications on Different Releases of Oracle Database
  You can encounter compatibility issues between different releases of Oracle Database that can affect your applications.
• Software Upgrades and Client and Server Configurations for Oracle Database
  Use these topics to understand your options for upgrading precompiler and Oracle Call Interface (OCI) applications, depending on the type of software upgrade that you are performing and your client and server configurations.
• Compatibility Rules for Applications When Upgrading Oracle Database Client or Server Software
  Compatibility rules apply when you upgrade Oracle Database client or server software.
• About Upgrading Precompiler and OCI Applications in Oracle Database
  Review this information if you want to upgrade precompiler and Oracle Call Interface (OCI) applications.
• Schema-Only Accounts and Upgrading EXPIRED Password Accounts
  Before starting your upgrade, determine if you want to use password authentication to default Oracle Database accounts where their passwords are in EXPIRED status, and their account is in LOCKED status
• About Upgrading Options for Oracle Precompiler and OCI Applications
  Oracle provides several options for upgrading your precompiler and Oracle Call Interface (OCI) applications running on a new release of Oracle Database.
• Upgrading SQL*Plus Scripts and PL/SQL after Upgrading Oracle Database
  To use features and functions of the new Oracle Database release, you must change existing SQL scripts to use the syntax of the new Oracle Database release.
• About Upgrading Oracle Forms or Oracle Developer Applications
  Review Oracle Forms and Oracle Developer new features to see if any of your applications can benefit from them.