title: ActiveMQ broker error messages: Async error occurred: java.lang.NullPointerException
body: <p>I got some messages as below in activemq.log,</p>
  <pre><code>Async error occurred: java.lang.IllegalStateException: Cannot add a producer to a connection that had not been registered: ID:BlackApple-2.local-50258-1366686550079-0:1 | org.apache.activemq.broker.TransportConnection.Service | ActiveMQ Transport: ssl:///&lt;ip&gt;:50264
  java.lang.IllegalStateException: Cannot add a producer to a connection that had not been registered: ID:BlackApple-2.local-50258-1366686550079-0:1
  
  Async error occurred: java.lang.NullPointerException | rg.apache.activemq.broker.TransportConnection.Service | ActiveMQ Transport: ssl:///&lt;ip&gt;:50264
  java.lang.NullPointerException
  
  Async error occurred: java.lang.IllegalStateException: Cannot remove a consumer from a connection that had not been registered: ID:BlackApple-2.local-50258-1366686550079-0:1 | org.apache.activemq.broker.TransportConnection.Service | ActiveMQ Transport: ssl:///&lt;ip&gt;:50264
  java.lang.IllegalStateException: Cannot remove a consumer from a connection that had not been registered: ID:BlackApple-2.local-50258-1366686550079-0:1
  </code></pre>
  <p>My broker version is 5.6, and I only have one broker(no cluster issue).
  What happened and how to fix these? Or is it safe to ignore these error messages?</p>
  <p>There are seldom information on the Internet...</p>
  <p>Thanks.</p>
  <p>EDIT: after getting the full stacktrace with log4j 2 format <code>%ex{full}</code> I got more details:</p>
  <pre><code>org.apache.activemq.transport.TransportDisposedIOException: peer (vm://broker-amq-2-1-tbk64#3) stopped.
      at org.apache.activemq.transport.vm.VMTransport.stop(VMTransport.java:230)
      at org.apache.activemq.transport.TransportFilter.stop(TransportFilter.java:65)
      at org.apache.activemq.transport.TransportFilter.stop(TransportFilter.java:65)
      at org.apache.activemq.transport.ResponseCorrelator.stop(ResponseCorrelator.java:132)
      at org.apache.activemq.broker.TransportConnection.doStop(TransportConnection.java:1189)
      at org.apache.activemq.broker.TransportConnection$4.run(TransportConnection.java:1155)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
      at java.lang.Thread.run(Thread.java:750)
  </code></pre>