reflex-dev/reflex · error · ValueError

The condition must be set

Error message

The condition must be set

What it means

The first argument to `rx.match` must be convertible to a Var. If `LiteralVar.create(cond)` returns None (None condition or an unsupported type), the condition is unusable and match cannot compare against any cases.

Source

Thrown at packages/reflex-components-core/src/reflex_components_core/core/match.py:82

    @classmethod
    def _create_condition_var(cls, cond: Any) -> Var:
        """Convert the condition to a Var.

        Args:
            cond: The condition.

        Returns:
            The condition as a base var

        Raises:
            ValueError: If the condition is not provided.
        """
        match_cond_var = LiteralVar.create(cond)

        if match_cond_var is None:
            msg = "The condition must be set"
            raise ValueError(msg)
        return match_cond_var

    @classmethod
    def _process_cases(
        cls, cases: list
    ) -> tuple[list[tuple], Var | BaseComponent | None]:
        """Process the list of match cases and the catchall default case.

        Args:
            cases: The list of match cases.

        Returns:
            The default case and the list of match case tuples.

        Raises:
            ValueError: If there are multiple default cases.
        """
        if not cases:

View on GitHub (pinned to 45b8ed5ab7)

Solutions

1. Pass a State var or literal: rx.match(State.kind, ...)
2. Guard None first: rx.match(cond or 'default', ...) or wrap with rx.cond(cond is not None, rx.match(cond, ...), fallback)
3. Use values of supported types (str/int/bool/Var/comparisons)

Example fix

# before
rx.match(get_status(), ('ok', 'OK'), 'other')  # may return None
# after
rx.match(State.status or 'unknown', ('ok', 'OK'), 'other')

cond_var = State.kind if State.kind is not None else 'default'
result = rx.match(cond_var, ('a', 1), 0)

def is_matchable(c) -> bool:
    return c is not None and isinstance(c, (str, int, float, bool, Var))

When it happens

Trigger: `rx.match(None, ...)`; passing a raw Python object LiteralVar can't serialize (arbitrary class instance, file handle); a refactor leaves the condition expression blank.

Common situations: Matching on an optional field that may be None without a guard; passing untyped API payloads directly as the match condition.

Related errors

• For cases with return types as Vars, a default case must be
• rx.match should have at least one case.
• rx.match should have tuples of cases and one default case as
• A case tuple should have at least a match case element and a
• Match condition {condition_index} of case {case_index} canno

AI-assisted analysis of reflex-dev/reflex@45b8ed5ab7 (2026-08-28). Data as JSON: /api/errors/ff8dbcb5d7846571. Report an issue: GitHub.