reflex-dev/reflex · critical · ChildrenTypeError

ChildrenTypeError(component=cls.__name__, child=child)

Error message

ChildrenTypeError(component=cls.__name__, child=child)

What it means

After fetching state from redis, Reflex type-checks the result: the deserialized object must be an instance of the requested state class, otherwise StateMismatchError. This catches schema/full-name collisions where stored state maps to a different class.

Source

Thrown at packages/reflex-base/src/reflex_base/components/component.py:1291

    def _get_components_in_props(self) -> Sequence[BaseComponent]:
        """Get the components in the props.

        Returns:
            The components in the props
        """
        return self._get_component_prop_property

    @classmethod
    def _validate_children(cls, children: tuple | list):
        from reflex_base.utils.exceptions import ChildrenTypeError

        for child in children:
            if isinstance(child, (tuple, list)):
                cls._validate_children(child)

            # Make sure the child is a valid type.
            if isinstance(child, dict) or not isinstance(child, ComponentChildTypes):
                raise ChildrenTypeError(component=cls.__name__, child=child)

    @classmethod
    def create(cls: type[T], *children, **props) -> T:
        """Create the component.

        Args:
            *children: The children of the component.
            **props: The props of the component.

        Returns:
            The component.
        """
        # Import here to avoid circular imports.
        from reflex_components_core.base.bare import Bare
        from reflex_components_core.base.fragment import Fragment

        # Filter out None props
        props = {key: value for key, value in props.items() if value is not None}

View on GitHub (pinned to 45b8ed5ab7)

Solutions

1. Flush the stale redis keys / use a distinct redis_db or key prefix per app
2. Ensure state class names and hierarchy are unique and stable across deployments
3. Use a proper redis_url per environment so apps don't share tokens

try:
    st = await self.get_state(OtherState)
except StateMismatchError:
    # stale/corrupt redis entry for this token
    await invalidate_token()

When it happens

Trigger: Redis returns an object whose class differs from state_cls — e.g. two state classes with the same full name across app versions, or corrupted/mismatched pickle data under a token.

Common situations: Deploying a renamed/restructured state while old tokens still exist in redis; multiple apps sharing one redis DB with colliding state names.

Related errors

• Undefined library for NoSSRComponent
• Do not override _add_style directly. Use add_style instead.
• The component `{comp_name}` only allows the components: {val
• Component must have a library to bundle.
• {self._prefixes[0]}REDIS_URL is required when using the redi

AI-assisted analysis of reflex-dev/reflex@45b8ed5ab7 (2026-08-28). Data as JSON: /api/errors/3c8b29be71942de1. Report an issue: GitHub.