nautechsystems/nautilus_trader · error

query_catalog_leg called with non-catalog-eligible variant {

Error message

query_catalog_leg called with non-catalog-eligible variant {leg:?}

What it means

query_catalog_leg only knows how to query the catalog for catalog-eligible RequestCommand variants; any other variant reaching its catch-all arm is a programming error. The engine treats this as an internal invariant violation rather than a user-facing condition, since dispatch_date_range_request should have routed non-eligible variants elsewhere.

Source

Thrown at crates/data/src/engine/streaming.rs:512

                ))
            }
            RequestCommand::BookDepth(cmd) => {
                let data: Vec<OrderBookDepth10> = catalog.order_book_depth10(
                    Some(vec![cmd.instrument_id.to_string()]),
                    Some(start_ns),
                    Some(end_ns),
                )?;
                Ok(build_book_depth_catalog_response(
                    cmd,
                    data,
                    start_ns,
                    end_ns,
                    used_client_id,
                    ts_init,
                ))
            }
            _ => {
                anyhow::bail!("query_catalog_leg called with non-catalog-eligible variant {leg:?}")
            }
        }
    }

    fn dispatch_instrument_catalog_request(&mut self, req: RequestCommand) -> anyhow::Result<()> {
        match req {
            RequestCommand::Instrument(cmd) => self.dispatch_instrument_request(cmd),
            RequestCommand::Instruments(cmd) => self.dispatch_instruments_request(cmd),
            _ => self.dispatch_request_to_client(req).map(|_| ()),
        }
    }

    fn dispatch_instrument_request(&mut self, cmd: RequestInstrument) -> anyhow::Result<()> {
        let force_instrument_update = cmd
            .params
            .as_ref()
            .and_then(|params| params.get_bool(PARAM_FORCE_INSTRUMENT_UPDATE))
            .unwrap_or(false);

View on GitHub (pinned to 18893faf8b)

Solutions

1. Add a match arm in query_catalog_leg for the new variant that performs its catalog query
2. Ensure non-catalog-eligible variants are filtered before reaching query_catalog_leg (they should dispatch straight to clients)
3. Check request_identifier/dispatch routing so only catalog-eligible variants enter the catalog path

Example fix

// before
_ => anyhow::bail!("query_catalog_leg called with non-catalog-eligible variant {leg:?}")
// after
RequestCommand::MyNewRequest(r) => Ok(self.query_my_new_request_catalog(r, start_ns, end_ns, used_client_id, ts_init)),
_ => anyhow::bail!("query_catalog_leg called with non-catalog-eligible variant {leg:?}")

fn is_catalog_eligible(cmd: &RequestCommand) -> bool {
    matches!(cmd, RequestCommand::QuoteTick(_) | RequestCommand::TradeTick(_) | RequestCommand::Bar(_) | RequestCommand::BookDeltas(_))
}

if !is_catalog_eligible(&req) { return dispatch_to_client_only(req); }

match query_catalog_leg(...) { Err(e) if e.to_string().contains("non-catalog-eligible") => fallback_to_client(req), other => other? }

When it happens

Trigger: A new RequestCommand variant is added and added to dispatch_date_range_request's identifier-based routing (request_identifier returns Some) but no catalog-leg match arm is written for it, so it falls through to the `_ =>` bail.

Common situations: Extending the data engine with a new request type during adapter development; refactoring the RequestCommand enum without updating query_catalog_leg's match; a bug routing an instrument request to the generic date-range path instead of dispatch_instrument_catalog_request.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• Cannot build empty catalog response for non-catalog-eligible
• RequestJoin must be handled by handle_request_join
• Cannot start bar aggregation for {bar_type}
• Account {account_id} not found after cache update
• No client registered with ID {client_id}

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/f82847b9ece00299. Report an issue: GitHub.