Socket.io bad request with response {"code":0,"message":"Transport unknown"}?

Question

I'm trying to run socket.io and I'm getting a bunch of these:

http://domain.com:8080/socket.io/?EIO=2&transport=polling&t=1401421022966-0 400 (Bad Request) 

This is the response I'm getting:

{"code":0,"message":"Transport unknown"}

I can't find any reason. I read somewhere that it might be misinterpreting the client, but that's about as far as I could get.

Answer 1

I had the same issue after upgrading from 0.9.x to 1.x.x. Shortening the long story, I would set transports to ['websocket', 'polling'] and then the error...

when you config your server to use specefic transpors you should set the same config on client side to...

server

    var io = require('socket.io')(server, {'transports': ['websocket', 'polling']});

client

    var io = io( serverUri, {'transports': ['websocket', 'polling']});

Answer 2

I had the same issue,after upgrading from 0.9.x, turns out my server config was set to ['websocket', 'jsonp-polling'] which was valid in 0.9 but the default config for the client and server is now ['polling', 'websocket']. Removing my server config got me up and running.

The config is now documented in engine.io (https://github.com/automattic/engine.io), the new transport layer introduced in 1.0 - in particular this line:
transports ( String): transports to allow connections to (['polling', 'websocket'])