Ideally, what we should do is to not send the task at all and instead set it directly as a job result with its throwable set to the NotSerializableException. The problem here is that the job header is already sent to the server, thus it is expecting the number of tasks specified in the header. One possibility is to send null instead of the task, and modifuy the serve rcode to immediately set this task as completed so it's not dispatched to a node, then send null back to the client, and modify the client code to discard any null task received. This will be done in the trunk and for the next major version