Now that Ops Center 12.3 is out, you might be wondering how to upgrade to it. I thought I'd walk you through the major steps involved in upgrading, and direct you to the documents that go into more detail.
First off, to upgrade directly to 12.3, you have to be using some variant of 12.2 - 12.2.0, 12.2.1, or 12.2.2. If you're on 12.1, you have to upgrade to 12.2 first. Here's a flowchart of the upgrade paths:
The Upgrade guide also walks you through the other planning steps. It's a good idea to look at the release notes and the Oracle Solaris and Linux install guides before you upgrade, to make sure that you're aware of known issues and the latest system requirements.
Once you've done your planning, you go to the Upgrade guide chapter that matches your environment - there are separate procedures for HA and non-HA environments, and separate procedures for upgrading from the command line or from the UI.
These chapters will walk you through downloading the upgrade (you can get it through the UI, from the Oracle Technology Network, or from the Oracle Software Delivery Cloud), and applying the upgrade to the Enterprise Controller(s), Proxy Controllers, and Agents.