psf/requests · error · KeyError

name= , domain= , path=

Error message

name={name!r}, domain={domain!r}, path={path!r}

What it means

Raised by RequestsCookieJar.__getitem__ (via the cookie-lookup loop) when no cookie matches the requested name, and optionally the domain and path filters. The KeyError's string contains the exact name/domain/path triple queried so you can see which key was missing. It is the standard 'cookie not found' signal for jar lookups.

Solutions

1. Use session.cookies.get(name, default) or the get(name, domain=, path=) method instead of subscript access to avoid the KeyError.
2. Verify the cookie exists with name in jar or by iterating the jar before accessing.
3. Confirm domain/path filters match the server's Set-Cookie attributes exactly (including leading dot).

Example fix

// before
value = session.cookies['sid']

// after
value = session.cookies.get('sid')
if value is None:
    # handle missing cookie
    ...

from requests.cookies import RequestsCookieJar

def get_cookie_or_none(jar: RequestsCookieJar, name, domain=None, path=None):
    # Use .get() instead of [] to avoid KeyError
    return jar.get(name, domain=domain, path=path)

from requests.cookies import RequestsCookieJar

def cookie_exists(jar: RequestsCookieJar, name, domain=None, path=None) -> bool:
    for c in jar:
        if c.name == name and (domain is None or c.domain == domain) and (path is None or c.path == path):
            return True
    return False

from requests.cookies import RequestsCookieJar

try:
    value = session.cookies['sid']
except KeyError as e:
    # e.args[0] contains 'name=..., domain=..., path=...'
    value = None

When it happens

Trigger: Indexing a session.cookies jar with a cookie name that was never set (session.cookies['sid']) or was deleted/expired; passing domain= or path= kwargs to jar['name'] that do not match any stored cookie; looking up a cookie whose domain attribute differs (e.g. '.example.com' vs 'example.com').

Common situations: Trying to read a session cookie before the server has set it; cookie scoping differences (the jar stores domain/path-qualified entries, so the same name can exist under multiple scopes); relying on a cookie set on a subdomain but querying with the apex domain.

Related errors

• Cookie headers should be added with…
• There are multiple cookies with name
• You can only merge into CookieJar
• Auth hooks must be callable.
• create_cookie() got unexpected keyword arguments

AI-assisted analysis of psf/requests@8068356288 (2026-08-11). Data as JSON: /api/errors/2db9511a196b24c2. Report an issue: GitHub.

Appendix: source

Thrown at src/requests/cookies.py:421

    ) -> str | None:
        """Requests uses this method internally to get cookie values.

        If there are conflicting cookies, _find arbitrarily chooses one.
        See _find_no_duplicates if you want an exception thrown if there are
        conflicting cookies.

        :param name: a string containing name of cookie
        :param domain: (optional) string containing domain of cookie
        :param path: (optional) string containing path of cookie
        :return: cookie.value
        """
        for cookie in iter(self):
            if cookie.name == name:
                if domain is None or cookie.domain == domain:
                    if path is None or cookie.path == path:
                        return cookie.value

        raise KeyError(f"name={name!r}, domain={domain!r}, path={path!r}")

    def _find_no_duplicates(
        self, name: str, domain: str | None = None, path: str | None = None
    ) -> str:
        """Both ``__get_item__`` and ``get`` call this function: it's never
        used elsewhere in Requests.

        :param name: a string containing name of cookie
        :param domain: (optional) string containing domain of cookie
        :param path: (optional) string containing path of cookie
        :raises KeyError: if cookie is not found
        :raises CookieConflictError: if there are multiple cookies
            that match name and optionally domain and path
        :return: cookie.value
        """
        toReturn = None
        for cookie in iter(self):
            if cookie.name == name:

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