As Martin pointed out, there is a race condition in the old code where a pipe could start shutting down after disconnection, but the new one could connect first. This connection would not get a pipe created for it, so the messages could never flow. The simplest way round this would be a flag, but it is possibly for a very bouncy but fast connection to go up and down twice I imagine, so instead I have added a counter. This starts at zero, and will null out the pipe if terminate is called while it is zero. On a disconnect situation the counter is incremented, and the pipe is the not nulled if the value is non zero. In the terminated function it is decremented for each pipe that is shut down, and the assertion that the terminated pipe == the current pipe is skipped while it is non-zero. This should deal with the race condition and not allow any extra terminated() calls without hitting the assertion.