nautechsystems/nautilus_trader · error

Cannot extract market ID from

Error message

Cannot extract market ID from {instrument_id}

What it means

extract_market_id parses a Betfair instrument ID whose symbol is expected in the form <marketId>-<selectionId>[-<handicap>]. If the symbol cannot be split into at least two '-'-separated parts, no market ID can be extracted and this error is raised.

Solutions

1. Build the instrument ID as '<marketId>-<selectionId>' (optionally '-<handicap>') per Betfair conventions
2. Validate the symbol format with extract_market_id/extract_selection_id before use
3. Regenerate the instrument ID from the Betfair catalog rather than constructing it manually

Example fix

// before
let instrument_id = InstrumentId::from("BETFAIR.WIN");
// after
let instrument_id = InstrumentId::from("BETFAIR.1.23456789-12345");

fn valid_betfair_symbol(symbol: &str) -> bool {
    let mut it = symbol.splitn(2, '-');
    it.next().map_or(false, |m| !m.is_empty()) && it.next().map_or(false, |s| s.parse::<u64>().is_ok())
}

fn as_betfair_instrument_id(id: &InstrumentId) -> Option<String> {
    extract_market_id(id).ok()
}

match extract_market_id(&instrument_id) {
    Ok(market_id) => subscribe(market_id).await,
    Err(e) => { log::error!("bad Betfair instrument id: {e}"); Err(e) }
}

When it happens

Trigger: Calling extract_market_id (directly or via subscribe_book_deltas, submit_order, cancel_order, modify_order) with an InstrumentId whose symbol contains no '-' separator, e.g. 'BETFAIR' instead of '1.23456789-12345'.

Common situations: Hand-constructing instrument IDs without the market-selection format; using instrument IDs from another adapter; stripping the suffix when normalizing symbols.

Understand the failure class

Background: "invalid id" errors: invalid identifier format — why libraries reject IDs before lookup, and how to fix them — this error's family across 37 libraries.

Related errors

• Cannot extract selection ID from
• cannot derive currency from
• Cannot expand parent subscription for
• {FAILED}: {e}
• Failed to parse instrument ID from key

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/29985f6e2062b358. Report an issue: GitHub.

Appendix: source

Thrown at crates/adapters/betfair/src/common/parse.rs:493

    )
    .with_info(info))
}

/// Extracts the Betfair market ID from a Nautilus instrument ID.
///
/// Instrument IDs follow the format `{market_id}-{selection_id}.BETFAIR`
/// or `{market_id}-{selection_id}-{handicap}.BETFAIR`.
///
/// # Errors
///
/// Returns an error if the symbol does not contain a hyphen separator.
pub fn extract_market_id(instrument_id: &InstrumentId) -> anyhow::Result<String> {
    let symbol = instrument_id.symbol.as_str();
    let parts: Vec<&str> = symbol.splitn(3, '-').collect();
    if parts.len() >= 2 {
        Ok(parts[0].to_string())
    } else {
        anyhow::bail!("Cannot extract market ID from {instrument_id}")
    }
}

/// Extracts the selection ID and handicap from a Nautilus instrument ID.
///
/// # Errors
///
/// Returns an error if the symbol cannot be parsed into the expected format.
pub fn extract_selection_id(
    instrument_id: &InstrumentId,
) -> anyhow::Result<(SelectionId, Decimal)> {
    let symbol = instrument_id.symbol.as_str();
    let parts: Vec<&str> = symbol.splitn(3, '-').collect();
    if parts.len() < 2 {
        anyhow::bail!("Cannot extract selection ID from {instrument_id}");
    }

    let selection_id: SelectionId = parts[1]

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