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Connection shutdown throwing Uncaught TypeError: Cannot read property 'sid' of undefined

See original GitHub issue

[x] report a bug [ ] request a feature

Current behaviour

When initiating a connection, if there’s a rejection (I.E.: WebSocket is closed before the connection is established), the connection is shut down and the following error message is shown:

Uncaught TypeError: Cannot read property 'sid' of undefined
 at Socket.onpacket (socket.js:189)
    at Manager.<anonymous> (index.js:21)
    at Manager.Emitter.emit (index.js:145)
    at Manager.ondecoded (manager.js:209)
    at Decoder.<anonymous> (index.js:21)
    at Decoder.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.Emitter.emit (index.js:145)

Steps to reproduce

I have simply instantiated a new connection with a WebSocket server with default settings passing a custom namespace.

Expected behaviour

I expected this variable to have some check to see if it’s undefined to prevent this error.

Setup

OS: Linux Mint 19
browser: Tested in Google Chrome Version 87.0.4280.66 (Official Build) (64-bit)
socket.io version: 3.0.3

Other information

To fix, change the following code on socket.ts file on line 227, adding the optional chaining operator to validate the object:

// socket.ts - line 227

 case PacketType.CONNECT:
        const id = packet?.data?.sid;
        this.onconnect(id);
        break;

Issue Analytics

State:
Created 3 years ago
Reactions:1
Comments:5 (2 by maintainers)

Top GitHub Comments

2reactions

darrachequesnecommented, Dec 3, 2020

Hi, it seems you are trying to reach a Socket.IO server in v2 with a client in v3, but they are not compatible.

We will add a check for this, as this is a common question: https://github.com/socketio/socket.io-client/commit/dddd63a48f52d558a96accfc7025e9a25b2bfc6a

0reactions

darrachequesnecommented, Dec 7, 2020

An error will now be emitted when reaching a v2.x server: https://github.com/socketio/socket.io-client/commit/ec1f8c3474b54600420487a0554cb195cc78f2bc (included in socket.io-client@3.0.4).

I think this issue can now be closed.

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