The requested module 'socket.io' does not provide an export named 'default' after upgrade to 3.0

Note: for support questions, please use one of these channels: stackoverflow or slack

For bug reports and feature requests for the Swift client, please open an issue there.

For bug reports and feature requests for the Java client, please open an issue there.

You want to:

• report a bug
• request a feature

Current behaviour

What is actually happening?

import SocketIO from "socket.io";
export const io = SocketIO(server, {
    pingInterval: 10000,
    pingTimeout: 5000,
});

Then i get an error in console:

import SocketIO from "socket.io";
       ^^^^^^^^
SyntaxError: The requested module 'socket.io' does not provide an export named 'default'

Steps to reproduce (if the current behaviour is a bug)

1. Install socket.io 3.0 and node 15.0.1
2. Enable type: “module” and --es-module-specifier-resolution=node
3. Get error

Note: the best way (and by that we mean the only way) to get a quick answer is to provide a failing test case by forking the following fiddle.

Expected behaviour

Importing and running like before

What is expected?

Setup

• OS: Mac os Catalina
• browser: no browser
• socket.io version: 3.0

Other information (e.g. stacktraces, related issues, suggestions how to fix)

[darrachequesne]

You’re right, this part was missing from the migration guide, sorry for that.

Server:

import { Server } from "socket.io";

const io = new Server(httpServer);

Client:

import io from "socket.io-client";

const socket = io();

// or, more explicit version
import { Manager } from "socket.io-client";

const manager = new Manager("https://example.com");
const socket = manager.socket("/");

[Sjonnie2nd]

I got it working with

import {Server, Socket} from 'socket.io'; const io = new Server(server);

But after it: be aware to update the client-side to 3.0.0 too! https://github.com/socketio/socket.io-client