Node.js + express 3 + socket.io = Unable to set headers after sending them

Question

I am new to learning node.js and seem to be facing an error that cannot be fixed.

Its code is very simple and new, so it doesn’t need a lot of explanation, moreover, it works fine on localhost, but it crashes into a production server.

App.js

var express = require('express') , routes = require('./routes') , http = require('http') , path = require('path'); var app = express(); app.configure(function(){ app.set('port', process.env.PORT || 8000); app.set('views', __dirname + '/views'); app.set('view engine', 'jade'); app.use(express.favicon()); app.use(express.logger('dev')); app.use(express.bodyParser()); app.use(express.methodOverride()); app.use(app.router); app.use(express.static(path.join(__dirname, 'public'))); }); app.configure('development', function(){ app.use(express.errorHandler()); }); app.get('/', routes.index); var server = app.listen(8000); var io = require('socket.io').listen(server); server.listen(app.get('port'), function(){ console.log("Express server listening on port " + app.get('port')); }); 

And here is a terrible mistake!

 http.js:644 throw new Error('Can\'t set headers after they are sent.'); ^ Error: Can't set headers after they are sent. at ServerResponse.OutgoingMessage.setHeader (http.js:644:11) at ServerResponse.res.setHeader (/home1/artalatc/public_html/cloud1/node_modules/express/node_modules/connect/lib/patch.js:59:22) at next (/home1/artalatc/public_html/cloud1/node_modules/express/node_modules/connect/lib/proto.js:153:13) at Function.app.handle (/home1/artalatc/public_html/cloud1/node_modules/express/node_modules/connect/lib/proto.js:198:3) at Server.app (/home1/artalatc/public_html/cloud1/node_modules/express/node_modules/connect/lib/connect.js:66:31) at Manager.handleRequest (/home1/artalatc/public_html/cloud1/node_modules/socket.io/lib/manager.js:564:28) at Server.<anonymous> (/home1/artalatc/public_html/cloud1/node_modules/socket.io/lib/manager.js:118:10) at Server.EventEmitter.emit (events.js:115:20) at HTTPParser.parser.onIncoming (http.js:1793:12) at HTTPParser.parserOnHeadersComplete [as onHeadersComplete] (http.js:111:23) 

The problem seems to be in var io = require('socket.io').listen(server); , because commenting of this type eliminates the error.

Answer 1

What version of Node are you using?

I had the same problem when I used 0.9.x. I downgraded Node to 0.8.4 and the problem seems to be gone.

My best guess is that Node has changed that Socket.io disagrees with.

Answer 2

Update express - 3.1.0 and socket.io - 0.9.13

this is normal on nodejs0.10

Answer 3

What version of express do you use? Check out https://github.com/visionmedia/express/wiki/Migrating-from-2.x-to-3.x or try the following:

 var server = app.listen(8000); var io = require('socket.io').listen(server); 

Answer 4

I had the same pairing

if you are using express 3.0, you should try the following: http://codehenge.net/blog/2012/08/using-socket-io-with-express-3-x/

also check your version of node:

 node --version 

try using v0.8.9 or any other stable version

It helps me! And help you

Answer 5

For those facing this problem, you should use:

 var server = require('http').createServer(app); var io = require('socket.io').listen(server); server.listen(8000); 

As an expression, it no longer returns the HTTP instance that socket.io requires. See the Updated README.md file at https://github.com/learnboost/socket.io for express examples 2 and 3.

Answer 6

This approach works in the current stable release 0.8.14:

 var express = require('express') , app = express() , server = app.listen(8000) , io = require('socket.io').listen(server); 

Answer 7

I had the same problem. Incompatible versions of express and socket.io are to blame. Upgraded them to express 3.2.4 and socket.io 0.9.14 and works like a charm.

Or you can change your .io socket to a previous version, but you will have to display this.

Answer 8

this error occurs because the expression internally uses caching for every second request for data from the cache, so it returns a response with a status code of 304, so use

 app.disable('etag'); 

it tells express to every request fresh means using stautscode 200

Answer 9

Change socket.io dependency to 0.9.15 in package.json, run npm install and it should fix your problem.

Answer 10

Run npm list socket.io

Make sure that it does not appear as invalid.

─ socket.io@0.9.10 invalid

npm ERR! invalid: socket.io@0.9.10 c: \ Users ....

If you get this error, npm install socket.io. Also make sure the same with other packages.