UnknownFactoryKwargError

Symptom

Raised at Factory(...) declaration time, listing the kwargs key(s) that don't match the creator's signature, the known parameter names, and a "did you mean" suggestion when a close match exists.

Cause

A key in kwargs={...} doesn't correspond to any parameter of the creator — usually a typo, or a key left over after the creator's signature was renamed/refactored. The creator has no **kwargs catch-all, so modern-di can validate the keys eagerly at declaration time rather than only failing at call time.

Fix

Match the kwargs keys to the creator's actual parameter names:

def create_service(connection_string: str) -> Service: ...


class Dependencies(Group):
    # Wrong: typo — raises UnknownFactoryKwargError, suggests "connection_string"
    service = providers.Factory(
        create_service, scope=Scope.APP, kwargs={"conection_string": "..."}
    )

    # Right
    service = providers.Factory(
        create_service, scope=Scope.APP, kwargs={"connection_string": "..."}
    )

If the creator genuinely accepts arbitrary keyword arguments (**kwargs in its signature), this check is skipped automatically — no escape hatch needed.

See also

• Factories: kwargs.