nautechsystems/nautilus_trader · error

Missing `exchange` for record: {e}

Error message

Missing `exchange` for record: {e}

What it means

For GLBX.MDP3 publisher records when `use_exchange_as_venue` is enabled, the loader calls `rec.exchange()` to derive the venue from the record's exchange code. If the record carries no exchange field the map_err wraps the failure as this error.

Source

Thrown at crates/adapters/databento/src/loader.rs:282

                let result: anyhow::Result<Option<InstrumentAny>> = (|| {
                    let record = dbn::RecordRef::from(rec);
                    let msg = record
                        .get::<InstrumentDefMsg>()
                        .ok_or_else(|| anyhow::anyhow!("Failed to decode InstrumentDefMsg"))?;

                    let raw_symbol = rec
                        .raw_symbol()
                        .map_err(|e| anyhow::anyhow!("Error decoding `raw_symbol`: {e}"))?;
                    let symbol = Symbol::from(raw_symbol);

                    let publisher = rec
                        .hd
                        .publisher()
                        .map_err(|e| anyhow::anyhow!("Invalid `publisher` for record: {e}"))?;
                    let venue = match publisher {
                        Publisher::GlbxMdp3Glbx if use_exchange_as_venue => {
                            let exchange = rec.exchange().map_err(|e| {
                                anyhow::anyhow!("Missing `exchange` for record: {e}")
                            })?;
                            let venue = Venue::from_code(exchange).map_err(|e| {
                                anyhow::anyhow!("Venue not found for exchange {exchange}: {e}")
                            })?;
                            self.symbol_venue_map.insert(symbol, venue);
                            venue
                        }
                        _ => *self
                            .publisher_venue_map
                            .get(&msg.hd.publisher_id)
                            .ok_or_else(|| {
                                anyhow::anyhow!(
                                    "Venue not found for publisher_id {}",
                                    msg.hd.publisher_id
                                )
                            })?,
                    };
                    let instrument_id = InstrumentId::new(symbol, venue);

View on GitHub (pinned to 18893faf8b)

Solutions

1. Set `use_exchange_as_venue = false` so the venue comes from the publisher map instead of the exchange field
2. Verify the dataset/record type actually carries an exchange field (check schema version)
3. Update the `dbn` crate and re-export the data, since newer schemas populate exchange consistently
4. Filter out records with empty exchange before feeding the loader

Example fix

// before
let loader = DatabentoInstrumentLoader::new(publisher_venue_map, true);
// after
let loader = DatabentoInstrumentLoader::new(publisher_venue_map, false); // fall back to publisher_id venue mapping

// only use exchange-as-venue for GLBX data whose records carry exchange codes
let use_exchange_as_venue = dataset == "GLBX.L3" && schema_supports_exchange(schema);

match loader.load_instruments(file) {
    Ok(i) => i,
    Err(e) if e.to_string().contains("Missing `exchange`") => {
        // retry with publisher-based venue mapping
        DatabentoInstrumentLoader::new(publisher_venue_map, false).load_instruments(file)
    }
    Err(e) => return Err(e),
}

When it happens

Trigger: Reading definition records with `use_exchange_as_venue = true` where a GLBX.MDP3 record lacks the exchange field (e.g. certain instrument definition schemas or record types that omit exchange).

Common situations: Loading older GLBX definition datasets where exchange was not populated, or feeding non-GLBX records mislabeled with the GlbxMdp3Glbx publisher.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• Missing exchange in record: {e}
• Invalid `publisher` for record: {e}
• AX whoami account {} supplied no fee rates
• DEX {} does not have initialize event set.
• Missing fee in topic3 when parsing pool created event

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/3e201e208babdedc. Report an issue: GitHub.