Problem after updating from 2.0.2 to 2.0.3 with middleware

This error occurred the first time after updating from 2.0.2 to 2.0.3 - I really can’t figure it out right now.

/data/project/app/node_modules/on-headers/index.js:25
	throw new TypeError('argument res is required')
	^

TypeError: argument res is required
	at onHeaders (/data/project/app/node_modules/on-headers/index.js:25:11)
	at session (/data/project/app/node_modules/express-session/index.js:219:5)
	at Array.<anonymous> (/data/project/app/modules/webserver.js:41:5)
	at run (/data/project/app/node_modules/socket.io/lib/namespace.js:123:11)
	at Namespace.run (/data/project/app/node_modules/socket.io/lib/namespace.js:135:3)
	at Namespace.add (/data/project/app/node_modules/socket.io/lib/namespace.js:163:8)
	at Client.connect (/data/project/app/node_modules/socket.io/lib/client.js:76:20)
	at Server.onconnection (/data/project/app/node_modules/socket.io/lib/index.js:398:10)
	at emitOne (events.js:115:13)
	at Server.emit (events.js:210:7)
error: Forever detected script exited with code: 1
error: Script restart attempt #63

const session = require('express-session');
[..]
const httpsServer = https.createServer(credentials, app).listen(config.server.port);
const io = require('socket.io')(httpsServer);

var sessionMiddleware = session({
    store: new RedisStore({}),
    secret: 'MYSECRET',
    resave: false,
    saveUninitialized: true
});

io.use(function (socket, next) {
    sessionMiddleware(socket.request, socket.request.res, next); //(/data/project/app/modules/webserver.js:41:5)
});

[ToddAlvord]

I found that this works. sessionMiddleware( socket.request, {}, next );

You will have access to your session via socket.request.session. The res part is used to notify the session handler to check if it should save the session data or not after a request has completed. I never could get session data to save automatically with socket.io, even in v1. If you need to make changes to your session in a socket.io connection you can use socket.request.session.save(). Basically remove the res part as it wasn’t being used anyways by socket.io. At least not in a way that seems to have any affect.

[akontsevich]

@ToddAlvord thanks for the solution! Think it could be improved a little:

io.use(function(socket, next) {
    sessionMiddleware(socket.request, socket.request.res || {}, next);
});