nautechsystems/nautilus_trader · error

Wrong template ID: expected {balance_update_event_codec::SBE

Error message

Wrong template ID: expected {balance_update_event_codec::SBE_TEMPLATE_ID}, received {template_id}

What it means

After parsing the SBE header, decode_balance_update validates the template ID field against balance_update_event_codec::SBE_TEMPLATE_ID. The template ID identifies which SBE message the payload encodes; a mismatch means the bytes are a different SBE message than a balance update. The library bails rather than misinterpreting another message type.

Source

Thrown at crates/adapters/binance/src/spot/websocket/trading/decode_sbe.rs:343

///
/// Returns error if the buffer is too short, the template ID is wrong,
/// or the schema ID does not match.
pub fn decode_balance_update(data: &[u8]) -> anyhow::Result<BinanceSpotBalanceUpdateMsg> {
    if data.len() < HEADER_LEN {
        anyhow::bail!(
            "Buffer too short for SBE header: expected {HEADER_LEN}, was {}",
            data.len()
        );
    }

    let buf = ReadBuf::new(data);
    let block_length = buf.get_u16_at(0);
    let template_id = buf.get_u16_at(2);
    let schema_id = buf.get_u16_at(4);
    let version = buf.get_u16_at(6);

    if template_id != balance_update_event_codec::SBE_TEMPLATE_ID {
        anyhow::bail!(
            "Wrong template ID: expected {}, received {template_id}",
            balance_update_event_codec::SBE_TEMPLATE_ID
        );
    }

    if schema_id != crate::spot::sbe::spot::SBE_SCHEMA_ID {
        anyhow::bail!(
            "Wrong schema ID: expected {}, received {schema_id}",
            crate::spot::sbe::spot::SBE_SCHEMA_ID
        );
    }

    let min_len = HEADER_LEN + block_length as usize;
    if data.len() < min_len {
        anyhow::bail!(
            "Buffer too short for fixed block: expected {min_len}, was {}",
            data.len()
        );

View on GitHub (pinned to 18893faf8b)

Solutions

  1. Verify the dispatch/multiplexing logic routes only balance-update events to this decoder
  2. Log the received template_id and compare against balance_update_event_codec::SBE_TEMPLATE_ID
  3. Regenerate/check the SBE codecs if Binance schema versions changed
  4. Decode with a generic SBE header read first to identify the message type, then dispatch

Example fix

// before
let msg = decode_balance_update(&payload)?;
// after
let template_id = u16::from_be_bytes([payload[2], payload[3]]);
if template_id != balance_update_event_codec::SBE_TEMPLATE_ID {
    tracing::debug!(template_id, "not a balance update");
    return Ok(None);
}
let msg = decode_balance_update(&payload)?;
Defensive patterns

Strategy: validation

Validate before calling

let is_balance_update = payload.len() >= 4
    && u16::from_be_bytes([payload[2], payload[3]]) == balance_update_event_codec::SBE_TEMPLATE_ID;

Type guard

fn is_balance_update_frame(data: &[u8]) -> bool {
    data.len() >= 4
        && u16::from_be_bytes([data[2], data[3]]) == balance_update_event_codec::SBE_TEMPLATE_ID
}

Try / catch

match decode_balance_update(&payload) {
    Ok(msg) => handle_balance(msg),
    Err(e) if e.to_string().starts_with("Wrong template ID") => {
        log::debug!("wrong template, dispatching to other decoder");
    }
    Err(e) => return Err(e),
}

Prevention

When it happens

Trigger: Passing an SBE payload whose template ID differs from the balance-update template, e.g. an execution report, order update, or other event routed to decode_balance_update by mistake.

Common situations: A websocket message-dispatch switch that routes by stream name but receives a different message on that stream; Binance changing template IDs in a schema update; feeding one decoder the output intended for another event type.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/d4a7e7d43a005b06. Report an issue: GitHub.