Puppeteer: Unexpected string partition key

Cookie filtering received a string partition key where its filtering path expected a composite object.

Error message

Unexpected string partition key

How this error happens

The shared cookie-filtering path expects a composite partition-key object when applying a partition filter. A browser path that returns a string key can violate that assumption.

The snippets use a BrowserContext named context containing a preference cookie with a string partition key.

await context.deleteMatchingCookies({
    name: "preference",
    partitionKey: "https://example.com",
});

How to fix

Read cookies, match the returned key shape explicitly, then delete the exact returned cookies through the public API.

const cookies = await context.cookies();

const matching = cookies.filter((cookie) => {
    if (cookie.name !== "preference") {
        return false;
    }

    const partitionKey = typeof cookie.partitionKey === "string"
        ? cookie.partitionKey
        : cookie.partitionKey?.sourceOrigin;

    return partitionKey === "https://example.com";
});

await context.deleteCookie(
    ...matching
);

Things to keep in mind

This keeps each selected cookie’s domain, path and partition key. The first call only fails when a matching cookie has the unexpected string-shaped key. Do not remove the partition filter and delete every same-named cookie.

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