nautechsystems/nautilus_trader · error

Failed to decode initialize event data: {e}

Error message

Failed to decode initialize event data: {e}

What it means

Thrown by `parse_initialize_event_hypersync` when the ABI decode of the log's data section fails after passing the 160-byte length check. The data should decode into `InitializeEventData` (sqrtPriceX96, tick, protocolFee, lpFee, hooks). A decode error means the bytes don't match the expected ABI layout.

Source

Thrown at crates/adapters/blockchain/src/exchanges/parsing/uniswap_v4/initialize.rs:135

            .ok_or_else(|| anyhow::anyhow!("Missing currency1 topic"))?
            .as_ref()
            .get(12..32)
            .ok_or_else(|| anyhow::anyhow!("Invalid currency1 topic length"))?,
    );

    if let Some(data) = log.data {
        let data_bytes = data.as_ref();

        // Validate minimum data length (5 fields × 32 bytes = 160 bytes)
        if data_bytes.len() < 160 {
            anyhow::bail!(
                "Initialize event data too short: expected at least 160 bytes, was {}",
                data_bytes.len()
            );
        }

        let decoded = <InitializeEventData as SolType>::abi_decode(data_bytes)
            .map_err(|e| anyhow::anyhow!("Failed to decode initialize event data: {e}"))?;

        let mut event = PoolCreatedEvent::new(
            block_number,
            currency0,
            currency1,
            pool_manager_address, // V4 pools are managed by PoolManager
            PoolIdentifier::PoolId(pool_identifier), // Pool ID (bytes32 as hex string)
            Some(decoded.fee.to::<u32>()),
            Some(i32::try_from(decoded.tick_spacing)? as u32),
        );

        event.set_initialize_params(decoded.sqrtPriceX96, i32::try_from(decoded.tick)?);
        event.set_hooks(decoded.hooks);

        Ok(event)
    } else {
        Err(anyhow::anyhow!("Missing data in initialize event log"))
    }

View on GitHub (pinned to 18893faf8b)

Solutions

1. Log the raw `e` from the alloy decode error and hex of `data_bytes` to see which field failed.
2. Confirm the `InitializeEventData` sol! definition matches the deployed Uniswap V4 contract's event (field order/types).
3. Decode manually (offsets of 32 bytes per field) for the specific log to verify the layout.
4. Update the adapter/ABI if the pool manager version on the target chain differs.

Example fix

// before
let decoded = <InitializeEventData as SolType>::abi_decode(data_bytes)
    .map_err(|e| anyhow::anyhow!("Failed to decode initialize event data: {e}"))?;
// after
let decoded = <InitializeEventData as SolType>::abi_decode(data_bytes).with_context(|| {
    format!("decode failed for tx {:?}, data: {}", log.transaction_hash.as_deref().map(hex::encode), hex::encode(data_bytes))
})?;

// precondition check before decode
if log.data.as_ref().map(|d| d.as_ref().len() % 32 != 0 || d.as_ref().len() < 160).unwrap_or(true) {
    return Ok(None);
}

match parse_initialize_event_hypersync(&log) {
    Ok(ev) => store(ev),
    Err(e) if e.to_string().starts_with("Failed to decode initialize event data") => {
        quarantine_log(&log, e); // keep hex for later ABI review
    }
    Err(e) => return Err(e),
}

When it happens

Trigger: Calling `parse_initialize_event_hypersync` with a log whose `data` field passes the 160-byte length check but whose contents do not conform to the `InitializeEventData` ABI layout (e.g. extra/missing words, non-standard encoding from a fork).

Common situations: Parsing logs from a Uniswap V4 fork whose Initialize event has extra/renamed parameters; ABI type drift (uint160 vs uint256, int24 packing) after an alloy sol! definition update; indexer returning corrupted data payloads.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Swap event data is too short
• Failed to decode swap event data: {e}
• Missing tickLower in topic2 when parsing burn event
• Missing poolId topic
• Missing currency0 topic

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/9e5b87871dc09c63. Report an issue: GitHub.