What is required in order for an upgrade of the Java Agent to succeed?

To upgrade the AppDynamics Java Agent, you need to copy the existing agent directory to a backup location and replace it with the new agent directory. You also need to copy any configuration file changes made in the old directory to the new agent directory. After that, you need to restart the application JVM where the Java Agent is installed, so that the new agent can take effect. Restarting the application JVM is the only required step for the upgrade to succeed. You do not need to restart the host machine, the Machine Agent, or the AppDynamics Controller12. References: Upgrade the Java Agent, Release Upgrade Checklist for Java Agents