nautechsystems/nautilus_trader · error

Missing transaction index in the log

Error message

Missing transaction index in the log

What it means

extract_transaction_index reads a Hypersync log's optional transaction_index and converts it to u32. The error fires when the field is absent, since ordering of events within a transaction cannot be determined without it.

Source

Thrown at crates/adapters/blockchain/src/hypersync/log.rs:61

///
/// Returns an error if the transaction hash is not present in the log.
pub fn extract_transaction_hash(log: &HypersyncLog) -> anyhow::Result<String> {
    log.transaction_hash
        .as_ref()
        .map(ToString::to_string)
        .ok_or_else(|| anyhow::anyhow!("Missing transaction hash in log"))
}

/// Extracts the transaction index from a log entry
///
/// # Errors
///
/// Returns an error if the transaction index is not present in the log.
pub fn extract_transaction_index(log: &HypersyncLog) -> anyhow::Result<u32> {
    log.transaction_index
        .as_ref()
        .map(|index| **index as u32)
        .ok_or_else(|| anyhow::anyhow!("Missing transaction index in the log"))
}

/// Extracts the log index from a log entry
///
/// # Errors
///
/// Returns an error if the log index is not present in the log.
pub fn extract_log_index(log: &HypersyncLog) -> anyhow::Result<u32> {
    log.log_index
        .as_ref()
        .map(|index| **index as u32)
        .ok_or_else(|| anyhow::anyhow!("Missing log index in the log"))
}

/// Extracts the block number from a log entry
///
/// # Errors
///

View on GitHub (pinned to 18893faf8b)

Solutions

1. Ensure the HyperSync query/request includes transaction_index in the selected fields
2. Skip or re-fetch logs lacking transaction_index
3. Update hypersync-client if a version regression drops the field

Example fix

// before
let idx = extract_transaction_index(&log)?;
// after
let Some(idx) = log.transaction_index.as_ref().map(|i| **i as u32) else {
    tracing::warn!("log missing transaction_index; skipping");
    return Ok(None);
};

fn has_tx_index(log: &HypersyncLog) -> bool {
    log.transaction_index.is_some()
}
// only call extract_transaction_index when this returns true

fn log_has_tx_index(log: &HypersyncLog) -> bool {
    log.transaction_index.is_some()
}

let idx = match extract_transaction_index(&log) {
    Ok(i) => i,
    Err(e) => { tracing::warn!("log lacks tx index: {e}"); return Ok(None); }
};

When it happens

Trigger: Calling extract_transaction_index with a HypersyncLog whose transaction_index is None (partial/underspecified log from a HyperSync response).

Common situations: HyperSync responses with missing index fields due to schema drift or partial decoding; custom log pipelines constructing logs without the index; tests using minimal log fixtures.

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

• Missing transaction hash in log
• Missing log index in the log
• Missing block number in the log
• Profiler log has no block hash
• Profiler watermark log has no event signature

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/091425cfff8bc5ba. Report an issue: GitHub.