Channels: Error: Django can only handle ASGI/HTTP connections, not websocket.

[gojuukaze]

my setup:

Django==3.0.3
channels==2.4.0
channels-redis==2.4.2
daphne==2.4.1

run command:

daphne myproduct.asgi:application

I got 500 server error when I connenct websocket .

log:

127.0.0.1:54023 - - [12/Mar/2020:16:51:21] "WSCONNECTING /ws/robot" - -
2020-03-12 16:51:22,104 ERROR    Exception inside application: Django can only handle ASGI/HTTP connections, not websocket.
  File "/Users/xx/project/xx/venv/lib/python3.7/site-packages/daphne/cli.py", line 30, in asgi
    await self.app(scope, receive, send)
  File "/Users/xx/project/xx/venv/lib/python3.7/site-packages/django/core/handlers/asgi.py", line 146, in __call__
    % scope['type']
  Django can only handle ASGI/HTTP connections, not websocket.
127.0.0.1:54023 - - [12/Mar/2020:16:51:22] "WSDISCONNECT /ws/robot" - -

[carltongibson]

Django's ASGI handler does not support web sockets.

You're still going to need to use Channel's ProtocolTypeRouter as per the tutorial here.
You'll need to point daphne to (e.g.) myproduct.routing:application.

The thing you can do with Django 3.0. is route http traffic to Django's ASGIHander, rather than have Channels use its own. (Adding that to the docs would be a good example.)

[jack-michaud]

Was experiencing this, I modified django's default asgi.py to what it says in the docs (using from channels.routing import get_default_application instead of django's django.core.asgi.get_asgi_application) and it worked fine.

I also tried to use django's asgi application in the protocol router but I think there may be an interface difference.

Channels' HTTP asgi handler: https://github.com/django/channels/blob/master/channels/http.py#L179
Django's asgi handler: https://github.com/django/django/blob/master/django/core/handlers/asgi.py#L136

As a result, I don't think you _can_ use Django's ASGIHandler.
Channels' works fine for me though.

[carltongibson]

Hi @jack-michaud. Yes. Currently this is the case. It's a difference between ASGI v2 and v3.

Progress for this should be made in #1421 by @jaydenwindle. At that point we should be able to accept a single callable (the ASGI v3 version that Django's new code implements) and the idea above should hold. 🤞

Goal now is a channels update to use ASGI 3 (allowing fallback for existing apps) throughout.
I have stuff for the next version of DRF top of my list, and then it's Channels after that. If you fancy lending a hand, that would be super.

[johnthagen]

For those tracking this, it looks like work continues in #1479 and #1480.

[CrazyCatCZ]

Make sure you have DEBUG = True in development