The EJBClient protocol handler on the server side, org.jboss.as.ejb3.remote.protocol.versionone.VersionOneProtocolChannelReceiver, will send out a full cluster topology report to a connecting EJBClient. This will happen in particular when the client reconnects after a server which was initially up went down and came up again.

If the server is not clustered, the report gets sent out anyway, and erroneously with an empty message body. This message gets processed on the client side by org.jboss.ejb.client.remoting.ChannelAssociation.processResponse() which cannot recognize the message header. The exception results.

One way to fix this is to only send out the cluster topology message if the node is actually clustered.