nautechsystems/nautilus_trader · error

Missing data in pair created event log

Error message

Missing data in pair created event log

What it means

parse_pool_created_event_hypersync throws this when the PairCreated log's data field is entirely absent (None), so the pair address and count cannot be extracted. Unlike the too-short variant, no bytes were provided at all, meaning the log record is incomplete.

Source

Thrown at crates/adapters/blockchain/src/exchanges/parsing/uniswap_v2/pool_created.rs:74

            "PairCreated event data too short: expected at least 32 bytes, was {}",
            data_bytes.len()
        );

        // Extract pair address (first 32 bytes, address is right-aligned)
        let pair_address = Address::from_slice(&data_bytes[12..32]);
        let pool_identifier = PoolIdentifier::Address(Ustr::from(&pair_address.to_string()));

        Ok(PoolCreatedEvent::new(
            block_number,
            token0,
            token1,
            pair_address,
            pool_identifier, // For V2/V3, pool_identifier = pool_address
            None,            // V2 has no fee tiers (fixed 0.3%)
            None,            // V2 has no tick spacing (CPAMM)
        ))
    } else {
        Err(anyhow::anyhow!("Missing data in pair created event log"))
    }
}

/// Parses a UniswapV2 PairCreated event from an RPC log.
///
/// # Errors
///
/// Returns an error if the log parsing fails or if the event data is invalid.
pub fn parse_pool_created_event_rpc(log: &RpcLog) -> anyhow::Result<PoolCreatedEvent> {
    rpc_log::validate_event_signature(log, PAIR_CREATED_EVENT_SIGNATURE_HASH, "PairCreatedEvent")?;

    let block_number = rpc_log::extract_block_number(log)?;
    let token0 = rpc_log::extract_address_from_topic(log, 1, "token0")?;
    let token1 = rpc_log::extract_address_from_topic(log, 2, "token1")?;

    // Extract pair address from data
    let data_bytes = rpc_log::extract_data_bytes(log)?;

View on GitHub (pinned to 18893faf8b)

Solutions

1. Re-query with the data column included in the hypersync selection
2. Skip and retry the record — the pair address exists only in the log data
3. Fall back to an RPC eth_getLogs fetch for the same block/tx to recover full log data
4. Validate the ingestion pipeline config includes non-indexed event parameters

Example fix

// before
let parsed = parse_pool_created_event_hypersync(&log)?;
// after
let parsed = match parse_pool_created_event_hypersync(&log) {
    Ok(p) => p,
    Err(e) if e.to_string().contains("Missing data") => fetch_via_rpc(&log.tx_hash)?,
    Err(e) => return Err(e),
};

fn has_data(log: &Log) -> bool { log.data.is_some() }

fn log_data(log: &Log) -> Option<&Bytes> { log.data.as_ref() }

match parse_pool_created_event_hypersync(&log) {
    Ok(p) => use(p),
    Err(e) if e.to_string() == "Missing data in pair created event log" => fetch_via_rpc(&log.tx_hash),
    Err(e) => Err(e),
}

When it happens

Trigger: A hypersync log record for PairCreated arrives with data == None, typically because the ingestion query excluded the data column or the record is corrupt.

Common situations: Data-provider column selection misconfigured; partial ingestion failures; fetching logs from a source that strips non-topic fields.

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 data in swap event log
• PairCreated event data too short: expected at least 32 bytes
• Topic must be at least 32 bytes, was {}
• Invalid event signature for '{event_name}': expected {expect
• Included wrap transaction {tx_hash} has invalid block number

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/bcce08be573e4842. Report an issue: GitHub.