Connection won't be closed when exception occurred in AsyncHttpConsumer::handle() and handle() have sent nothing using send() or send_body(). So client will be hanged there until timeout, with nothing received. In server-side, there is no exception traceback/information logged.
We can reproduce this case using following codes:

class DemoHttpConsumer(AsyncHttpConsumer):
  async def handle(self, body):
    raise ValueError()

I have read codes, it's because the exception occurred in handle() is ignore in

If send() something in AsyncHttpConsumer::handle(). Daphne will send {"type": "http.disconnect"} message in here:
https://github.com/django/daphne/blob/333f4644d1a5a167c85eca967a52e4e10a7db0bd/daphne/http_protocol.py#L257-L258

            if not message.get("more_body", False):
                self.finish()
                logger.debug("HTTP response complete for %s", self.client_addr)

which make all coroutines exit.

Now I am selecting a web-socket framework used in my company's project.
Because I am a novice in python asynchronies programming and channels, I'm sorry can't submit a patch to fix it. So can you fix this problem soon?