nautechsystems/nautilus_trader · error

Ask required

Error message

Ask required

What it means

Same quote-dependency as the 'Bid required' error: for `TriggerType::Default`, `BidAsk`, or `LastOrBidAsk` the trailing basis is the ask (for Buy side) or bid (for Sell side), and both quotes must be supplied. Here `ask: Option<Price>` was `None`, so the calculation cannot proceed and returns this anyhow error.

Source

Thrown at crates/execution/src/trailing.rs:137

    match trigger_type {
        TriggerType::LastPrice | TriggerType::MarkPrice => {
            let last = last.ok_or(OrderError::InvalidStateTransition)?;
            let cand_trigger = compute(trailing_offset, last)?;
            new_trigger_price = maybe_move(&mut trigger_price, cand_trigger, better_trigger);

            if order_type == OrderType::TrailingStopLimit {
                let limit_offset = order.limit_offset().ok_or_else(|| {
                    anyhow::anyhow!("Missing `limit_offset` for trailing stop limit calculation")
                })?;
                let cand_limit = compute(limit_offset, last)?;
                new_limit_price = maybe_move(&mut limit_price, cand_limit, better_limit);
            }
        }
        TriggerType::Default | TriggerType::BidAsk | TriggerType::LastOrBidAsk => {
            let (bid, ask) = (
                bid.ok_or_else(|| anyhow::anyhow!("Bid required"))?,
                ask.ok_or_else(|| anyhow::anyhow!("Ask required"))?,
            );
            let basis = match order_side {
                OrderSide::Buy => ask,
                OrderSide::Sell => bid,
            };
            let cand_trigger = compute(trailing_offset, basis)?;
            new_trigger_price = maybe_move(&mut trigger_price, cand_trigger, better_trigger);

            if order_type == OrderType::TrailingStopLimit {
                let limit_offset = order.limit_offset().ok_or_else(|| {
                    anyhow::anyhow!("Missing `limit_offset` for trailing stop limit calculation")
                })?;
                let cand_limit = compute(limit_offset, basis)?;
                new_limit_price = maybe_move(&mut limit_price, cand_limit, better_limit);
            }

            if trigger_type == TriggerType::LastOrBidAsk {
                let last = last.ok_or_else(|| anyhow::anyhow!("Last required"))?;

View on GitHub (pinned to 18893faf8b)

Solutions

1. Pass the current `ask` (and `bid`) from the quote cache when invoking the calculator.
2. Defer the update until both bid and ask are present: check `ask.is_some() && bid.is_some()` before calling.
3. Use a `LastPrice`/`MarkPrice` trigger type instead if only last-trade data is reliably available.
4. Verify the market-data subscription is configured for quotes on the instrument.

Example fix

// before
let result = trailing_stop_calculate(increment, None, &order, bid, None, last)?;
// after
if let (Some(bid), Some(ask)) = (bid, ask) {
    let result = trailing_stop_calculate(increment, None, &order, Some(bid), Some(ask), last)?;
} else {
    // defer update until quotes available
}

fn ask_available(ask: Option<Price>, trigger_type: TriggerType) -> Result<(), String> {
    if matches!(trigger_type, TriggerType::Default | TriggerType::BidAsk | TriggerType::LastOrBidAsk)
        && ask.is_none()
    {
        return Err("ask quote not yet available; defer trailing update".into());
    }
    Ok(())
}

if let Err(e) = update_trailing_stop_order(&mut order, bid, ask, last) {
    if e.to_string().contains("Ask required") {
        // retry on next quote tick
        return Ok(());
    }
    return Err(e.into());
}

When it happens

Trigger: Calling `trailing_stop_calculate`/`update_trailing_stop_order` with `trigger_type` in {Default, BidAsk, LastOrBidAsk} and `ask: None` — typical when only the bid side of the book is populated or no ask quote has been received yet.

Common situations: Fresh instrument subscription where the ask hasn't arrived; one-sided/illiquid book; feed disruption dropping ask updates; strategy passing only trade data while the order expects quotes.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• Bid required
• callbackRate {rate}% out of Binance range [{min_rate}, {max_
• BitMEX only supports PRICE trailing offset type, was {offset
• Unknown IB historical tick type: {value}
• Subscription error: {e:?}

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/7dcd513d126ecfc2. Report an issue: GitHub.