How to safely detach CDP sessions before calling `page.close()` in Puppeteer?

General Discussions
1

I’m using Puppeteer and creating a CDP (Chrome DevTools Protocol) session with page.target().createCDPSession() to simulate user gestures.

let browser = await puppeteer.launch(options);
const page = await browser.newPage();
const session = await page.target().createCDPSession();

await session.send('Input.synthesizeScrollGesture', { 
  x: 100,
  y: 200,
  yDistance: -150
});

The issue: if I call page.close() while the scroll gesture or any CDP command is still running, Puppeteer crashes with errors like:

TargetCloseError: Protocol error (Input.synthesizeScrollGesture): Target closed

I’m looking for a safe way to detach or clean up CDP sessions before closing the page to prevent these errors. Has anyone figured out a reliable method or sequence to gracefully end CDP sessions before calling page.close() when using puppeteer.createCDPSession?

2

I ran into the same crash while automating scroll gestures. What helped me was explicitly detaching the CDP session before closing the page.

You can call:

await session.detach();
await page.close();

This ensures the CDP connection is released first. Also, make sure no pending commands are running - for example, wait for the scroll gesture to complete or wrap it with a small delay using await new Promise(r => setTimeout(r, 200)); before closing.

In short:

  1. Send your CDP commands

  2. Wait for them to finish

  3. Then call session.detach()

  4. Finally close the page

That sequence completely stopped the TargetCloseError in my scripts.

3

This happens because the page is closed while the DevTools session is still processing commands.

Puppeteer doesn’t auto-detach CDP sessions, so it’s up to you to clean up.

What I do is wrap my CDP actions in a try…finally block:

const session = await page.target().createCDPSession();
try {
  await session.send('Input.synthesizeScrollGesture', { x: 100, y: 200, yDistance: -150 });
} finally {
  await session.detach();
  await page.close();
}

That way, even if something fails mid-command, you still detach cleanly before the page closes.

4

When I first saw the TargetCloseError, I thought it was a timing issue - and it was. The trick was to avoid closing the page while CDP was still active.

My final working flow:

  1. Wait for the command to finish

  2. Detach the session

  3. Close the page

Something like this works smoothly:

await session.send('Input.synthesizeScrollGesture', { x: 100, y: 200, yDistance: -150 });
await session.detach();
await page.close();

If you have multiple sessions, detach them all before calling page.close(). After that, Puppeteer stops throwing the error.