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[Error] Cannot read property 'sid' of undefined

See original GitHub issue

Hi! I migrated to the latest version 3.0.3. But on the client-side, I’m getting this error immediately after connecting:

error

socket.js:189 Uncaught TypeError: Cannot read property 'sid' of undefined
    at Socket.onpacket (socket.js:189)
    at Manager.<anonymous> (index.js:21)
    at Manager../node_modules/component-emitter/index.js.Emitter.emit (index.js:145)
    at Manager.ondecoded (manager.js:209)
    at Decoder.<anonymous> (index.js:21)
    at Decoder../node_modules/component-emitter/index.js.Emitter.emit (index.js:145)
    at Decoder.add (index.js:117)
    at Manager.ondata (manager.js:201)
    at Socket.<anonymous> (index.js:21)
    at Socket../node_modules/component-emitter/index.js.Emitter.emit (index.js:145)

client-side

const options = {
 path: '/ws',
 query: { accessToken: 'XXXX', id: 'XXXXXX' },
 transports: ['websocket']
};

const socket = io("http://localhost:3030/my-namespace", options);
socket.on("connection:error", payload => console.log(payload)); // <-- This not listen but received (Network Tab)
socket.on("disconnect", reason => console.log(reason)); // <-- This works

server-side

const options = {
  pingTimeout: 5000,
  pingInterval: 5000,
  path: '/ws/'
};

const server = require('http').createServer();
const io = require('socket.io')(server, options);
server.listen(3000);

What I’m doing wrong? Thanks!

Issue Analytics

State:
Created 3 years ago
Comments:6 (3 by maintainers)

Top GitHub Comments

2reactions

darrachequesnecommented, Dec 2, 2020

It seems you are using a v3 client with a v2 server, which are not compatible. Could you please check?

0reactions

darrachequesnecommented, Dec 17, 2020

For future readers: this issue happened when one tries to reach a v2 Socket.IO server with a v3 client (which is not possible due to incompatible exchange protocols). We have added a check for that case (https://github.com/socketio/socket.io-client/commit/ec1f8c3474b54600420487a0554cb195cc78f2bc), so this issue should be fixed.

In order to upgrade an existing deployment, please see https://socket.io/docs/v3/migrating-from-2-x-to-3-0/#How-to-upgrade-an-existing-production-deployment

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