reflex-dev/reflex · error · ValueError

Memo name collision for `{key[0]}`: `{existing.fn.__module__

Error message

Memo name collision for `{key[0]}`: `{existing.fn.__module__}.{existing.python_name}` and `{definition.fn.__module__}.{definition.python_name}` both compile to the same memo name in the same module.

What it means

Beyond arity, @rx.dynamic requires the single parameter to carry a type hint resolving to the page's state class. Missing or extra type hints raise DynamicComponentInvalidSignatureError.

Source

Thrown at packages/reflex-base/src/reflex_base/components/memo.py:559

    """Register a memo definition.

    Args:
        definition: The memo definition to register.

    Raises:
        ValueError: If another memo already compiles to the same exported name.
    """
    key = _memo_registry_key(definition)
    if (existing := MEMOS.get(key)) is not None and (
        not _is_memo_reregistration(existing, definition)
    ):
        msg = (
            f"Memo name collision for `{key[0]}`: "
            f"`{existing.fn.__module__}.{existing.python_name}` and "
            f"`{definition.fn.__module__}.{definition.python_name}` both compile "
            "to the same memo name in the same module."
        )
        raise ValueError(msg)

    MEMOS[key] = definition


def _annotation_inner_type(annotation: Any) -> Any:
    """Unwrap a Var-like annotation to its inner type.

    Args:
        annotation: The annotation to unwrap.

    Returns:
        The inner type for the annotation.
    """
    if _is_rest_annotation(annotation):
        return dict[str, Any]

    annotation = _strip_annotated(annotation)
    origin = get_origin(annotation) or annotation

View on GitHub (pinned to 45b8ed5ab7)

Solutions

1. Annotate the parameter with the state class: `def page(state: PostState) -> rx.Component`
2. Ensure PostState subclasses rx.State and is imported at decoration time

Example fix

// before
@rx.dynamic(route="/post/[pid]")
def post(state): ...
// after
@rx.dynamic(route="/post/[pid]")
def post(state: PostState) -> rx.Component: ...

import inspect
sig = inspect.signature(fn)
(p,) = sig.parameters.values()
assert p.annotation is not inspect.Parameter.empty, "annotate the state param"

When it happens

Trigger: `def page(state): ...` (no annotation) under @rx.dynamic; or annotations resolving to zero/multiple entries after signature inspection.

Common situations: Omitting annotations for brevity; hinting with a non-state type; IDE auto-stripping type hints in optimized builds.

Related errors

• No default value or factory provided.
• Route part `{part}` with argument is not valid. Reflex only
• ChildrenTypeError(component=cls.__name__, child=child)
• Do not override _add_style directly. Use add_style instead.
• The component `{comp_name}` cannot have `{child_name}` as a

AI-assisted analysis of reflex-dev/reflex@45b8ed5ab7 (2026-08-28). Data as JSON: /api/errors/35fc16e2fd3f1330. Report an issue: GitHub.