Error with uWebSockets.js: uWS.HttpResponse must not be accessed after uWS.HttpResponse.onAborted callback

[eighthlucky]

Describe the bug
When running socket.io and uNetworking/uWebSockets.js, we sometimes get this error:

Error: uWS.HttpResponse must not be accessed after uWS.HttpResponse.onAborted callback, or after a successful response. See documentation for uWS.HttpResponse and consult the user manual.

It happens rarely (~10 times in last 30 days). We've recently come up with a way to replicate it locally, although I'm not sure if it's the same cause as on production.

To Reproduce

Engine.IO server version: 6.6.0
Engine.IO client version: 6.5.4

import { Server } from 'socket.io';
import { connect } from 'socket.io-client';
import { App as createApp } from 'uWebSockets.js';

const PORT = 3000;
const SERVER_URL = `http://localhost:${PORT}`;

// Initialize socket.io server with uWebSockets app
const server = new Server({ serveClient: false });
const app = createApp();
server.attachApp(app);

// Listen and wait for it to be ready
await new Promise((r) => app.listen(PORT, r));

// Create a new socket.io client and wait for it to connect
const socket = connect(SERVER_URL);
await new Promise((r) => socket.once('connect', r));

// Mimic a new socket.io client connection with an already connected session ID
// Engine.io will close the connection, but will incorrectly attempt to upgrade it afterwards
// See https://github.com/socketio/engine.io/blob/6.6.0/lib/userver.ts#L213
try {
  new WebSocket(
    `ws://localhost:3000/socket.io/?EIO=4&transport=websocket&sid=${socket.io.engine.id}`,
  );
} catch {}

// Exit when there is no error
setTimeout(() => process.exit(0), 2_000);

Note: The above snippet will require Node 22 to run.

Expected behavior
I expect it to exit normally after the 2s timeout.

Actual behavior
It crashes with the error message mentioned above.

Platform:

• Device: MacBook Pro 2019
• OS: Ventura
• Node versions: 20.13.1, 20.15.0, 22.3.0

Additional context

• I have a branch that replicates the issue: https://github.com/eighthlucky/npm-bug-replication/tree/engine.io-uWS.HttpResponse
  • It also has a patch which seems to fix the issue on my end
• We can also replicate this in the browser by trying to open a duplicate WebSocket connection via the console (similar to the above approach)
  • Just copy+paste the WebSocket URL from the browser's network inspector

[darrachequesne]

For future readers:

This should be fixed by d5095fe, included in [email protected] and [email protected].

[eighthlucky]

Thanks!