📡 Networking

CORS problem (No 'Access-Control-Allow-Origin') on client

Freshabout 8 years ago

Mar 14, 20260 views

Confidence Score78%

78%

Problem

Hi all, Typically if you do have server with sockets on another domain and you do simple first line `io('YOUR_HOST')`, you will receive this message: `XMLHttpRequest cannot load YOUR_HOSTsocket.io/?EIO=3&transport=polling&t=1446467052356-0. No 'Access-Control-Allow-Origin'...` First appeared in head, that I need to look at documentation and find out how to set it from there, but eventually I did not find anything because of pure documentation. Then I entered source code and the only 2 usages of `setRequestHeader` method, which is actually allow you to do that, is only for setting content-type if POST method is chosen. Could you help me to fix this issue?

Unverified for your environment

Select your OS to check compatibility.

Your OS

OS version

Product version

1 Fix

Canonical Fix

High Confidence Fix

74% confidence100% success rate3 verificationsLast verified Mar 14, 2026

Solution: CORS problem (No 'Access-Control-Allow-Origin') on client

Low Risk

I am a bit confused by your code. The allowed origins option goes in your socket.io server not in the client i.e. in node.js code not in browser javascript that is part of a html page. Also I usually use a wildcard on the port and you can specify multiple allowed origins, just space them out like so: [code block] On the client side [code block]

Trust Score

3 verifications

100% success

I am a bit confused by your code. The allowed origins option goes in your socket

text

//in node.js
var app = require('express')();
var io = require('socket.io');
var server = require('http').createServer(app);
var allowedOrigins = "http://localhost:* http://127.0.0.1:*";
var path ='/stomp'; // you need this if you want to connect to something other than the default socket.io path

var sio_server = io(server, {
    origins: allowedOrigins,
    path : path
});
```

On the client side

```
var clientSocket = io({path:'/stomp'});

Validation

Resolved in socketio/socket.io GitHub issue #2294. Community reactions: 3 upvotes.

Verification Summary

Worked: 3

Partial: 1

Last verified Mar 14, 2026

Environment

Submitted by

Alex Chen

2450 rep