nautechsystems/nautilus_trader · error

Failed to deserialize instrument payload

Error message

Failed to deserialize instrument payload

What it means

OKX WebSocket message parsing failed to deserialize an instrument payload received on an instruments/status channel. The library bails with anyhow when serde cannot turn the raw `data` JSON into the expected instrument type, aborting processing of that message.

Source

Thrown at crates/adapters/okx/src/websocket/parse.rs:2410

                    maker_fee,
                    taker_fee,
                    ts_init,
                ) {
                    Ok(Some(inst_any)) => Ok(Some(NautilusWsMessage::Instrument(
                        Box::new(inst_any),
                        Some(status),
                    ))),
                    Ok(None) => {
                        log::warn!("Empty instrument payload: {msg:?}");
                        Ok(Some(NautilusWsMessage::InstrumentStatus(status)))
                    }
                    Err(e) => {
                        log::warn!("Failed to parse instrument {inst_key}: {e}");
                        Ok(Some(NautilusWsMessage::InstrumentStatus(status)))
                    }
                }
            } else {
                anyhow::bail!("Failed to deserialize instrument payload")
            }
        }
        OKXWsChannel::BboTbt => {
            let data_vec = parse_quote_msg_vec(
                data,
                instrument_id,
                price_precision,
                size_precision,
                ts_init,
            )?;
            Ok(Some(NautilusWsMessage::Data(data_vec)))
        }
        OKXWsChannel::Tickers => {
            let data_vec = parse_ticker_msg_vec(
                data,
                instrument_id,
                price_precision,
                size_precision,

View on GitHub (pinned to 18893faf8b)

Solutions

1. Log the raw message payload and compare it against the current OKX instruments channel schema in parse.rs
2. Update the deserialization structs/serde attributes in the OKX adapter to match the new OKX schema
3. Upgrade the nautilus_adapters/nautilus_trader package to a version with updated OKX parsing
4. Verify the message is actually routed to the correct channel parser (instruments vs event contracts)

Example fix

// before
anyhow::bail!("Failed to deserialize instrument payload")
// after
anyhow::bail!("Failed to deserialize instrument payload: {data:?}") // include payload for diagnosis; fix serde struct to match OKX schema

fn is_instrument_payload(msg: &serde_json::Value) -> bool {
    msg.get("data")
        .and_then(|d| d.as_array())
        .map(|a| a.iter().all(|o| o.get("instId").is_some()))
        .unwrap_or(false)
}

match parse_ws_message_data(msg) {
    Ok(Some(m)) => handle(m),
    Ok(None) => {},
    Err(e) => log::warn!("skip malformed OKX msg: {e}"),
}

When it happens

Trigger: An OKX WebSocket message on a channel mapping to OKXWsChannel::Instruments arrives whose `data` field cannot be deserialized into the expected instrument struct (e.g. OKX changed/added fields with incompatible types, message arrives with unexpected shape, or the wrong parser is used for the channel).

Common situations: OKX API schema updates introducing new field types; test fixtures or mocked payloads with malformed JSON; forwarding raw messages from endpoints (like event contract markets) that do not match the instrument schema.

Understand the failure class

Background: "failed to unmarshal" / json.Unmarshal errors: why parsing a response into a Go struct fails and how to fix it — this error's family across 23 libraries.

Related errors

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• Timeout waiting for account {account_id} to be registered af
• `api_key`, `api_secret`, `api_passphrase` credentials must b

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/b1dea3b43c1e8df7. Report an issue: GitHub.