nautechsystems/nautilus_trader · error

Missing log index in the log

Error message

Missing log index in the log

What it means

extract_log_index reads a Hypersync log's optional log_index and converts it to u32. The error fires when the log_index field is None; without it the event's position within the block's logs is unknown.

Source

Thrown at crates/adapters/blockchain/src/hypersync/log.rs:73

///
/// 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
///
/// Returns an error if the block number is not present in the log.
pub fn extract_block_number(log: &HypersyncLog) -> anyhow::Result<u64> {
    log.block_number
        .as_ref()
        .map(|number| **number)
        .ok_or_else(|| anyhow::anyhow!("Missing block number in the log"))
}

/// Extracts the event signature from a log entry and returns it as a hex string
///
/// # Errors
///

View on GitHub (pinned to 18893faf8b)

Solutions

1. Include log_index in the HyperSync query field selection
2. Skip or re-fetch logs that lack log_index
3. Verify the hypersync-client version populates log_index correctly

Example fix

// before
let log_idx = extract_log_index(&log)?;
// after
if log.log_index.is_none() {
    tracing::warn!("log missing log_index; skipping");
    return Ok(None);
}
let log_idx = extract_log_index(&log)?;

fn has_log_index(log: &HypersyncLog) -> bool {
    log.log_index.is_some()
}
// only call extract_log_index when this returns true

fn log_has_log_index(log: &HypersyncLog) -> bool {
    log.log_index.is_some()
}

let log_idx = match extract_log_index(&log) {
    Ok(i) => i,
    Err(e) => { tracing::warn!("log lacks log_index: {e}"); return Ok(None); }
};

When it happens

Trigger: Calling extract_log_index with a HypersyncLog whose log_index is None, typically from incomplete HyperSync log payloads.

Common situations: HyperSync queries not selecting log_index in the field selection; partial responses from the API; fixtures/tests constructing minimal logs.

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 transaction 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/bbd15e40212581fc. Report an issue: GitHub.