Description of problem:

There appears to be a NPE in the agent communications.

2014-01-13 12:57:59,746 ERROR [ClientCommandSenderTask Timer Thread #89264] (JBossRemotingRemoteCommunicator)- {JBossRemotingRemoteCommunicator.init-callback-failed}The initialize callback has failed. It will be tried again. Cause: java.lang.NullPointerException:null. Cause: java.lang
.NullPointerException

Also:

2014-01-13 12:57:59,746 WARN  [InventoryManager.availability-1] (InventoryManager)- Could not transmit availability report to server
java.lang.NullPointerException
        at org.jboss.remoting.Client.invoke(Client.java:2084)
        at org.jboss.remoting.Client.invoke(Client.java:879)
        at org.rhq.enterprise.communications.command.client.JBossRemotingRemoteCommunicator.rawSend(JBossRemotingRemoteCommunicator.java:514)
        at org.rhq.enterprise.communications.command.client.JBossRemotingRemoteCommunicator.sendWithoutCallbacks(JBossRemotingRemoteCommunicator.java:456)
        at org.rhq.enterprise.communications.command.client.JBossRemotingRemoteCommunicator.sendWithoutInitializeCallback(JBossRemotingRemoteCommunicator.java:475)
        at org.rhq.enterprise.agent.AgentMain.sendConnectRequestToServer(AgentMain.java:2112)
        at org.rhq.enterprise.agent.ConnectAgentInitializeCallback.sendingInitialCommand(ConnectAgentInitializeCallback.java:43)
        at org.rhq.enterprise.communications.command.client.JBossRemotingRemoteCommunicator.invokeInitializeCallbackIfNeeded(JBossRemotingRemoteCommunicator.java:579)
        at org.rhq.enterprise.communications.command.client.JBossRemotingRemoteCommunicator.send(JBossRemotingRemoteCommunicator.java:491)
        at org.rhq.enterprise.communications.command.client.AbstractCommandClient.invoke(AbstractCommandClient.java:143)
        at org.rhq.enterprise.communications.command.client.ClientCommandSender.send(ClientCommandSender.java:1084)
        at org.rhq.enterprise.communications.command.client.ClientCommandSenderTask.send(ClientCommandSenderTask.java:229)
        at org.rhq.enterprise.communications.command.client.ClientCommandSenderTask.call(ClientCommandSenderTask.java:107)
        at org.rhq.enterprise.communications.command.client.ClientCommandSenderTask.call(ClientCommandSenderTask.java:55)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:662)

Code:

public class Client implements Externalizable {
...
   private Object invoke(Object param, Map metadata, InvokerLocator callbackServerLocator)
         throws Throwable
   {
      if (isConnected())
      {
         return invoker.invoke(new InvocationRequest(sessionId, subsystem, param,
                                                     metadata, null, callbackServerLocator));

^^^ Seems that invoker is set to null. So it thinks it is connected but 'invoker' is somehow null.

Version-Release number of selected component (if applicable): 4.9


How reproducible: Unclear