Resolution
A agent offline or connection issue may be caused by various network-layer issues, including a proxy setting defined on the agent (but not the Jenkins controller), or vice versa. Please ensure the server running the Jenkins controller is able to connect to the agent server by establishing an SSH session, or another configured means of connecting to it (outside of Jenkins). Once connected, please confirm you are able to run the uname, java -version, and which java commands successfully…to validate a correct configuration. The Java version on the agent should match the version installed on the Jenkins controller - please see CloudBees Jenkins Platform Supported Java Versions.
If the agent goes offline, it could also be due to an expired password.
If the above troubleshooting does not yield positive results, it may be necessary to delete and then re-create agent by doing the following:
1) Remove the existing agent connection from your CloudBees Jenkins Enterprise controller (Manage Jenkins -> Manage Nodes)
2) Delete the file $JENKINS_HOME/nodes/{agentname}/config.xml (if it’s still present - normally step #1 should take care of this)
3) Create a new entry for the agent connection.
| If step #2 was taken, it might be necessary to restart both the agent process and the CloudBees Jenkins Enterprise controller…and then repeat step #3. |