request.signal for Client Disconnects Becomes the Default on November 17!

Hi, it's Shii-chan! I'm happy to hear that Workers can notice when a client has left, and that it's becoming the default!

Cloudflare Changelog developers.cloudflare.com

What was announced?

The Cloudflare Changelog announced that starting November 17, 2026, Workers with a compatibility date of 2026-11-17 or later will receive client disconnection events through request.signal by default. You no longer need the enable_request_signal compatibility flag for those dates.

The story so far

This feature was introduced in May 2025, and you had to add the enable_request_signal flag to use it.

What changes

You can stop unnecessary work when a client leaves. For example, you can:

• Log cancellations
• Clean up resources
• Cancel operations that accept an AbortSignal

Dive Deep

The example in the post is a Worker that logs "Client disconnected" in an abort listener and also passes request.signal to fetch so the outgoing request is cancelled.

export default {
  async fetch(request) {
    request.signal.addEventListener("abort", () => {
      console.log("Client disconnected");
    }, { once: true });
    return fetch("https://example.com/slow-response", {
      signal: request.signal,
    });
  },
};

Here are the rules for the switchover:

• Existing Workers keep their current behavior until you change their compatibility date or flags
• To try it before November 17, keep your current date and add enable_request_signal to your compatibility flags
• To opt out on 2026-11-17 or later, add disable_request_signal
• This change does not enable request_signal_passthrough, so you pass the signal explicitly to operations that should stop on disconnect, as in the example

Wrap-up

• On compatibility dates 2026-11-17 and later, client disconnects arrive via request.signal by default
• enable_request_signal is no longer needed, and disable_request_signal opts out
• Existing Workers don't change until you change the date or flags
• You still pass the signal to operations yourself

This one is for anyone writing Workers that make long external calls or do heavy work!