'Session ID unknown' after deploying to test environment with node.

[Xiaotou-Sophia]

Description：
It seems works fine in local development environment, and I got the right response. So I deploy all my client-end and server -end to test environment, but I got a 400 response with 'Session ID unknown'. BTW, there is only one node instance in the test environment, and I haven't used redis or other database in my socket related business yet.

Dev Environment:

• Client:

  • node : v14.0.0
  • "socket.io-client": "^4.5.1"
  • usage: socket.current = io(${window.location.origin});

• Server:

  • node: v14.0.0
  • "socket.io": "^4.5.1"
  • "express": "^4.17.1"
  • usage:

  const socket = require('socket.io');
  const io = socket(server);
  

Nginx config:

proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "Upgrade";

proxy_set_header Host $http_host;
proxy_set_header X-Client-Proto $scheme;
proxy_set_header X-Client-Proto-Ver $server_protocol;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

• Tried solution but did not solve my question:
  After checked many issues and responses , I tried add transports config like transports:[ 'websocket', 'polling'], in both my client-end and server-end , all of sudden, it doesn't work in my Dev environment, and it only work with transports:[ 'polling'],. But still , didn't work for my test environment.

[Xiaotou-Sophia]

issue like this:
{"code":1,"message":"Session ID unknown"}

[darrachequesne]

Hi! That's weird, I think the only way to get a session ID is unknown error is when you use several server instances: https://github.com/socketio/engine.io/blob/917d1d29e13f2e8f523c3738f6413f67b587aebe/lib/server.ts#L225-L229

Are you able to reliably reproduce?

Also, could you please try with transports: ['websocket'] on the client side?

[Xiaotou-Sophia]

Hi Damien, I'm glad to hear from you and now it works in my test environment. But it so tricky that after I added transports: ['websocket'] , my local dev environment got nothing from network and of course no socket response. So I added a logical judgment to distinguish the environment in the client side. But still, I wonder what's going on ? Why is such a difference.