JON agent initialization callback fails and agent is unable to communicate with server if server is in maintenance mode

Issue

• agent initialize callback has failed
• agent started but generated errors
• Agent fails to communicate with server due to NotProcessedException.

• Agent logs the following warning:

  WARN  [RHQ Server Polling Thread] (org.rhq.enterprise.agent.AgentMain)- {AgentMain.failover-failed}Failed to failover to another server. Cause: org.rhq.enterprise.communications.util.NotProcessedException
  WARN  [RHQ Server Polling Thread] (org.rhq.enterprise.agent.FailoverFailureCallback)- {AgentMain.too-many-failover-attempts}Too many failover attempts have been made [1]. Exception that triggered the failover: [org.rhq.enterprise.communications.util.NotProcessedException]
  

• Agent log contains the following error message:

  ERROR [RHQ Server Polling Thread] (enterprise.communications.command.client.JBossRemotingRemoteCommunicator)- {JBossRemotingRemoteCommunicator.init-callback-failed}The initialize callback has failed. It will be tried again. Cause: org.rhq.enterprise.communications.util.NotProcessedException:null
  

• Agent is unable to send commands to server:

  java.lang.IllegalStateException: The sender object is currently not sending commands now. Command not sent: [Command: type=[remotepojo]; cmd-in-response=[false]; config=[{rhq.timeout=1800000, rhq.send-throttle=true}]; params=[{invocation=NameBasedInvocation[mergeInventoryReport], targetInterfaceName=org.rhq.core.clientapi.server.discovery.DiscoveryServerService}]]