Puppeteer: Unknown selector type: {value}

A Puppeteer extended selector references an unregistered selector engine.

Error message

Unknown selector type: {value}

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

How this error happens

An extended selector names a query engine that Puppeteer has not registered. A made-up pseudo-element is not a CSS selector.

The snippets use an open Puppeteer page named page.

await page.$(
    "::-p-madeup(Save)"
);

How to fix

Use an existing engine such as text, or register the custom handler before using its name.

await page.setContent(
    '<button>Save</button>'
);

const save = await page.$(
    "::-p-text(Save)"
);

await save.click();

Things to keep in mind

Custom handler registration belongs to the Puppeteer instance performing the query, not another process.

All Puppeteer errors