Like the agent and other JBoss ON components, the CLI utility has a version. The CLI utility must be the same version as the JBoss ON server to which it is trying to connect.
If the local JBoss ON CLI is not the same version as the JBoss ON server to which it is trying to connect, then the connection is refused.
The CLI utility is not compatible with other versions of the JBoss ON server, neither newer nor older versions.
This behavior is configurable. There may be some instances where there is an external client or wrapper used with the JBoss ON CLI which does not (appear to) match the server version. To prevent the client connection from being rejected, add a Java option to disable the version checking property in the CLI configuration file.
[root@server ~]# vim cliRoot/rhq-remoting-cli-4.9.0.JON320GA/bin/rhq-cli-env.sh