Upgrading APEX is a very easy task. All we need to install the new APEX version to the database. Only one instance of Application Express can be active in the database so when we run the APEX installation script, it will detect existing APEX installation and upgrade it.
Then we need to update the /i/ (virtual directory) with the images, javascript, css, etc. For the standard HTTP Server installations, you can use copy command. If you use Embedded PL/SQL Gateway (EPG), you need to run apxldimg.sql script.
After the upgrade, you may need to modify some applications but most of them will work correctly. APEX also provides a utility to upgrade your applications and make them use the latest features.
