What causes "`handle_quote_tick` {IMPL_ERR} `{}`" in nautechsystems/nautilus_trader?

Implement handle_quote in your indicator type to extract the configured price from QuoteTick.

`handle_quote_tick` {IMPL_ERR} `{}`

Error message

`handle_quote_tick` {IMPL_ERR} `{}`

What it means

The default Indicator trait implementation of handle_quote bails immediately: it is a placeholder signaling that the concrete indicator must override handle_quote to process QuoteTicks. Hitting it means the indicator type was used polymorphically without providing its own quote-tick handler.

Source

Thrown at crates/indicators/src/indicator.rs:57

    fn handle_deltas(&mut self, deltas: &OrderBookDeltas) {
        panic!("`handle_deltas` {IMPL_ERR} `{}`", self.name());
    }

    fn handle_depth(&mut self, depth: &OrderBookDepth10) {
        panic!("`handle_depth` {IMPL_ERR} `{}`", self.name());
    }

    fn handle_book(&mut self, book: &OrderBook) {
        panic!("`handle_book_mbo` {IMPL_ERR} `{}`", self.name());
    }

    /// Updates the indicator with the given quote tick.
    ///
    /// # Errors
    ///
    /// Returns an error if the configured price type cannot be extracted from the quote.
    fn handle_quote(&mut self, quote: &QuoteTick) -> anyhow::Result<()> {
        anyhow::bail!("`handle_quote_tick` {IMPL_ERR} `{}`", self.name());
    }

    fn handle_trade(&mut self, trade: &TradeTick) {
        panic!("`handle_trade_tick` {IMPL_ERR} `{}`", self.name());
    }

    fn handle_bar(&mut self, bar: &Bar) {
        panic!("`handle_bar` {IMPL_ERR} `{}`", self.name());
    }

    fn reset(&mut self);
}

pub trait MovingAverage: Indicator {
    fn value(&self) -> f64;
    fn count(&self) -> usize;
    fn update_raw(&mut self, value: f64);
}

View on GitHub (pinned to 18893faf8b)

Solutions

Implement handle_quote in your indicator type to extract the configured price from QuoteTick.
If the indicator only supports bars/trades, stop feeding quote ticks to it and feed the supported update type.
Wrap registration in a check that the indicator declares quote-tick support before subscribing it to quote streams.

Example fix

// before
impl Indicator for MyIndicator { fn handle_bar(&mut self, bar: &Bar) { ... } }
// after
impl Indicator for MyIndicator {
    fn handle_quote(&mut self, quote: &QuoteTick) -> anyhow::Result<()> {
        self.update(quote.price_of(self.price_type));
        Ok(())
    }
}

Defensive patterns

Strategy: type-guard

Type guard

fn supports_quotes<I: Indicator>(ind: &I) -> bool {
    // Prefer an explicit capability flag on your indicator type
    ind.supports_quote_ticks()
}

Try / catch

// Rust: match on the error from handle_quote
match indicator.handle_quote(&quote) {
    Ok(()) => {}
    Err(e) if e.to_string().contains("IMPL_ERR") => {
        log::error!("indicator {} does not implement handle_quote", indicator.name());
    }
    Err(e) => return Err(e),
}

Prevention

Always override handle_quote when implementing the Indicator trait for quote-driven indicators.
Use a trait with default-panicking methods sparingly; document required overrides.
Test custom indicators with a QuoteTick before live deployment.

When it happens

Trigger: Calling handle_quote on an indicator struct that inherits the default trait impl instead of overriding it, i.e. feeding a quote tick into an indicator that only implemented handle_bar or left handle_quote unimplemented.

Common situations: Writing a custom indicator and forgetting to implement handle_quote; registering a partially implemented indicator in an indicator bundle driven by quote ticks; trait-object dispatch where the concrete type never overrode the method.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/4396032ad7cbe68c. Report an issue: GitHub.