Follow the below mentioned steps to upgrade from R12.2.2 to R12.2.3
Database Tier
Step 1 - Download and Apply following patches (if you are on StartCD 12.2.0.46):
Step 2 - Dowload and run Patch for Database Patch Checker (highly recommended) to find out the exact patches you must apply (based on your currently db verstion) to upgrade to R12.2.3 - 17537119
Application Tier
Step 3 - Download and apply following Application Tier patches (if you are on StartCD 12.2.0.46)
Step 4 - Web Tier and Utilities (OHS) 11.1.1.6 Patches and Bug Numbers - 17325559
Step 5 - Oracle Fusion Middleware Common 11.1.1.6 Patches and Bug Numbers – 12714567 (I had an issue in applying that it wouldn’t accept valid JRE and JDK paths – looks like a bug)
Step 6 - Oracle Weblogic Server 10.3.6.0 Patch and Bug Numbers – I had to play around with Weblogic Smart Update installer (in terms of uninstalling conflicting patches) since there were a number of dependencies and conflicts with already installed patches. Anyways, you must apply the following patches:
Step 7 - Apply Consolidated Seed Table Upgrade Patch (Required)
Step 8 - Apply the 12.2.3 AD and TXK Release Update Packs
Step 9 - Apply the 12.2.3 Suite-Wide Release Update Pack and associated help patch:
Step 10 - Run post upgrade steps of synchronizing the Patch and Run file systems using the command shown below:
adop phase=fs_clone workers=64
References - Database Tier
Oracle Support Document ID 1594274.1, Oracle E-Business Suite Release 12.2: Consolidated List of Patches and Technology Bug Fixes
References - Application Tier
Oracle Support Document ID 1586217.1, Applying the Release 12.2.3 AD and TXK Release Update Packs.
Oracle Support Document ID 1586214.1, Oracle E-Business Suite Release 12.2.3 Readme