Puppeteer: At least one query method must be implemented.

A custom query handler registration has neither queryOne nor queryAll.

Error message

At least one query method must be implemented.

How this error happens

registerCustomQueryHandler needs queryOne or queryAll. An empty object provides no way to find an element.

The snippets use the imported Puppeteer class for its static query-handler methods. The fix uses the same import.

import {
    Puppeteer,
} from "puppeteer";

Puppeteer.registerCustomQueryHandler(
    "custom",
    {}
);

How to fix

Implement at least one query method. Puppeteer can derive the other method from it.

Puppeteer.registerCustomQueryHandler(
    "custom",
    {
        queryOne: (root, selector) => {
            return root.querySelector(selector);
        },
    }
);

Things to keep in mind

Query functions run in the browser. They cannot read variables from your Node.js closure.

All Puppeteer errors