I am using web sockets with Redis on Django. Django is running fine on macOS server but I started running it on Redhat Linux server and now the server gives me this error whenever I send a package over websockets:
ERROR - server - HTTP/WS send decode error:
Cannot dispatch message on channel
u'daphne.response.fzdRCEVZkh!nqhIpaLfWb' (unknown)
Note: while I get the error, the package will be received correctly.
I couldn't find any resources for this error.
I followed official instructions for channels.
According to Andrew Godwin (the developer of the channels package), this message is logged when you have a channel that was disconnected, but not removed from channel group(s):
Ah yes, that's Daphne being a little bit more verbose than before, I need to remove that. Don't worry about it - it's perfectly normal after you disconnect a channel that's still in a group. You might want to add a Group.discard call in a disconnect handler to stop it, though.
I had the same error, using a custom impl of channels.generic.websockets.WebsocketConsumer. After cleaning up channels from groups in disconnect callback, the message disappeared.
A short example with a class-based consumer: assuming you add clients to the broadcast group named foo on connection establishing. Then, on client disconnect, remove its channel from the group:
from channels import Group
from channels.generic.websockets import JsonWebsocketConsumer
class MyConsumer(JsonWebsocketConsumer):
groupname = 'foo'
def connect(self, message, **kwargs):
# send an accept or the connection will be dropped automatically
self.message.reply_channel.send({"accept": True})
# add the channel to the broadcast group
Group(self.groupname).add(message.reply_channel)
# do the rest of logic that should happen on connection established
...
def disconnect(self, message, **kwargs):
Group(self.groupname).discard(message.reply_channel)
# do the rest of logic that should happen on disconnect
...