What you need to know and understand to do successful OS/400 Upgrades When doing an upgrade to OS/400, there is more work involved in the planning of the upgrade than in the actual upgrade itself. When you have done the planning, the actual upgrade is simple. We will cover planning tips, pre-requisites, and then post installation requirements. Your upgrade isn’t complete until this last step is done. While this presentation will focus on upgrading to V5R4, if you are upgrading to an earlier release, you will still learn a lot.