Puppeteer: Session {value} was not created.

A target-attached event references a session absent from the connection registry.

Error message

Session {value} was not created.

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

How this error happens

A target-attached event named a CDP session absent from Puppeteer’s registry. This can accompany session teardown or inconsistent browser/protocol event ordering.

The snippets use an open CDP-capable page named page. The first sequence illustrates a session lifecycle problem, not a guaranteed reproduction of an internal map failure.

const session = await page.createCDPSession();

await page.close();

await session.send(
    "Runtime.evaluate",
    {
        expression: "1 + 1",
    }
);

How to fix

Keep the page alive while using its session and clean up in order. Run the correction on a new open page.

const session = await page.createCDPSession();

try {
    const result = await session.send(
        "Runtime.evaluate",
        {
            expression: "1 + 1",
        }
    );

    console.log(result.result.value);
} finally {
    await session.detach();
    await page.close();
}

Things to keep in mind

The closure example can produce a session-closed error before reaching this particular registry check. If the exact error occurs without teardown, isolate custom transports, plugins and manual target-attachment commands. Do not supply guessed session IDs.

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