Puppeteer: Session already detached. Most likely the {value} has been closed.

detach is called on a CDP session already detached or whose target closed.

Error message

Session already detached. Most likely the {value} has been closed.

{value} is replaced by the value shown in your error message.

How this error happens

Detaching a session is a one-time cleanup operation. A second detach tries to remove a session that is already gone.

The snippets use an open Puppeteer page named page.

const session = await page.createCDPSession();

await session.detach();
await session.detach();

How to fix

Put session cleanup in one owner and call detach once.

const session = await page.createCDPSession();

try {
    await session.send(
        "Runtime.enable"
    );
} finally {
    await session.detach();
}

Things to keep in mind

If the target closes on its own, cleanup can also encounter a detached session. Treat expected target closure separately from an unexpected command failure.

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