What causes "Index prices not available for Spot instruments" in nautechsystems/nautilus_trader?

Subscribe to index prices only for Linear/Inverse/Option instruments

Index prices not available for Spot instruments

Error message

Index prices not available for Spot instruments

What it means

This error is raised when subscribing to index prices for a Spot instrument on Bybit. Index prices are only defined for derivatives (they track an underlying index), so Bybit does not offer an index-price stream for Spot and the adapter bails out before sending the WebSocket subscription.

Source

Thrown at crates/adapters/bybit/src/data.rs:1205

                async move {
                    ws.subscribe_ticker(instrument_id)
                        .await
                        .context("ticker subscription for mark prices")
                },
                "mark price subscription",
            );
        }
        Ok(())
    }

    fn subscribe_index_prices(&mut self, cmd: SubscribeIndexPrices) -> anyhow::Result<()> {
        let instrument_id = cmd.instrument_id;
        let product_type = self
            .get_product_type_for_instrument(instrument_id)
            .unwrap_or(BybitProductType::Linear);

        if product_type == BybitProductType::Spot {
            anyhow::bail!("Index prices not available for Spot instruments");
        }

        let mut should_subscribe = false;
        self.ticker_subs.rcu(|m| {
            let entry = m.entry(instrument_id).or_default();
            should_subscribe = entry.is_empty();
            entry.insert("index_prices");
        });

        if should_subscribe {
            let ws = self
                .get_ws_client_for_product(product_type)
                .context("no WebSocket client for product type")?
                .clone();

            self.spawn_ws(
                async move {
                    ws.subscribe_ticker(instrument_id)

View on GitHub (pinned to 18893faf8b)

Solutions

Subscribe to index prices only for Linear/Inverse/Option instruments
Use Spot ticker/quote data instead of index prices for Spot pairs
Check the instrument's product type before subscribing and branch accordingly

Example fix

// before
data_engine.subscribe_index_prices(InstrumentId::from("ETHUSDT.SBYBIT")); // Spot -> error
// after
let instrument = cache.instrument(&instrument_id).unwrap();
if instrument.product_type() != ProductType::SPOT { // guard
data_engine.subscribe_index_prices(instrument_id);
}

Defensive patterns

Strategy: validation

Validate before calling

let instrument = cache.instrument(&instrument_id).expect("instrument not found");
if is_spot_product(&instrument) {
    // use last_price/quote for spot instead of index price
    return Ok(());
}
data_engine.subscribe_index_prices(instrument_id)?;

Try / catch

match data_engine.subscribe_index_prices(instrument_id) {
    Err(e) if e.to_string().contains("Index prices not available for Spot") => {
        // fallback: subscribe to quotes for the spot pair
    }
    r => r?,
}

Prevention

Index prices exist only for derivatives; check product type first
Use a helper that routes subscriptions by product type
Avoid blanket 'subscribe to all feeds' loops over mixed instrument sets

When it happens

Trigger: Calling subscribe_index_prices with an instrument_id that resolves to BybitProductType::Spot via get_product_type_for_instrument (or the symbol suffix).

Common situations: Subscribing to index prices for a Spot pair by mistake; generic pricing pipelines that subscribe to every price feed for every instrument regardless of asset class.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/9ab787a816c1088e. Report an issue: GitHub.