After a manual upgrade of an Agent, it (magically) starts as the previous version.
Release : 12.0.x, 12.1.x, 12.2.x, 12.3.x, 21.x
Component : Unix, Windows or RA Agent
The Agent was automatically “repaired”, meaning upgraded or downgraded, to the latest version that corresponds to Centralized Agent Upgrade pack.
When an Agent has started, the AE checks in the database what the Target version of the Agent is. The following SQL statement shows this field:
select HOST_TargetVersion from HOST,OH where OH_idnr=HOST_OH_Idnr and OH_name='<AGENT_NAME>'
According to the documentation, if the CAU has been already successfully performed for an agent and the agent connects to the AE with a wrong target version subsequently, the CAU is repeated.
This means an upgrade is forced to bring the agent to the last target version that was selected in the last CAU action.
In this case in the Upgrade History of system client 0000 the entries titled "REPAIR" will show up to indicate that the agent was repaired by a forced upgrade to the desired target version.
How to Revert to a Previous Version:
You may want to revert the agent's upgrade in case your preferences or system occurrences make it seem appropriate.
This function is technically an upgrade to another agent version.
Therefore you just have to follow the steps described above for the CAU itself.
Alternatively, you can upgrade the Agent manually and use the option Skip Upgrade, so the CAU is not executed.
For a full explanation, see here: https://docs.automic.com/documentation/webhelp/english/ALL/components/DOCU/21.0.4/Automic%20Automation%20Guides/Content/Installation_Upgrade/install_cau_procedure.htm