One of the common errors seen when using the Agent Inventory agent upgrade is an error "Staging Failure". This gives an overview on how the Agent Inventory works
WCC works through AutoSys Application server to send a couple of adhoc command jobs to the target agent. These jobs are generated internally by the app server, so they are not jobs defined in Autosys or run by the scheduler.
The first command job creates some files in the agent spool directory.
The second command job executes a script (created by the first job) to download the agent installer from the WCC server. This is done by a Java based web service call back to the WCC server URL over the WCC port (8443 or 8080). So, ensure:
The WCC Server URL is resolvable from the Agent host
Connection from Agent to the WCC port is open for communication
If WCC URL is using SSL certificates, that SSL certificate and its certificate chain should be available for the Agent's Java layer (<AGENT_INSTALL_FOLDER>/cacerts keystore). If not, that chain should be manually imported into the cacerts keystore of the agent
If the above all are configured properly, there is a folder wcc_agent_cmd that gets created in the spool folder. In that folder there is a subdirectory with a very long name and a time stamp that gets created around the same time Staging or Upgrade of the Agent was attempted, example:
drwxr-xr-x. 2 root root 65 Mar 7 23:39 1678232369197-10dfeff726914416902c18ce91b0c52f
In that directory and there are files like below that can be reviewed for clues on why the operation failed. Correct appropriately and retry the Agent Inventory Upgrade/Stage