nautechsystems/nautilus_trader · error · anyhow::Error

Pool state at block {profiler_block} is ahead of the latest

Error message

Pool state at block {profiler_block} is ahead of the latest block {latest_block}; the execution RPC endpoint lags the data feed

What it means

validate_quote_age checks that the block at which pool state was read (from the profiler/data feed) is not newer than the latest block reported by the execution RPC endpoint. If the pool state block is ahead, the execution endpoint is lagging the data feed, and quote age cannot be computed correctly, so the library throws.

Source

Thrown at crates/adapters/blockchain/src/execution/client.rs:4270

    [
        Some(pool.dex.swap_created_event.as_ref()),
        Some(pool.dex.mint_created_event.as_ref()),
        Some(pool.dex.burn_created_event.as_ref()),
        Some(pool.dex.collect_created_event.as_ref()),
        pool.dex.flash_created_event.as_deref(),
        pool.dex.fee_protocol_update_event.as_deref(),
        pool.dex.fee_protocol_collect_event.as_deref(),
    ]
    .into_iter()
    .flatten()
}

fn validate_quote_age(
    profiler_block: u64,
    latest_block: u64,
    max_age_blocks: u64,
) -> anyhow::Result<()> {
    anyhow::ensure!(
        profiler_block <= latest_block,
        "Pool state at block {profiler_block} is ahead of the latest block {latest_block}; the execution RPC endpoint lags the data feed"
    );
    let quote_age = latest_block - profiler_block;
    anyhow::ensure!(
        quote_age <= max_age_blocks,
        "Stale quote: pool state at block {profiler_block}, latest block {latest_block}, exceeds `max_quote_age_blocks` {max_age_blocks}"
    );
    Ok(())
}

fn validate_rpc_transaction_matches_payload(
    transaction: &RpcTransaction,
    raw_transaction: &[u8],
) -> anyhow::Result<()> {
    let signed = decode_signed_transaction(raw_transaction)?;
    anyhow::ensure!(
        transaction.hash == signed.hash

View on GitHub (pinned to 18893faf8b)

Solutions

1. Point the execution RPC at a faster/fuller node (same provider tier as the data feed).
2. Refresh the latest block from the execution endpoint and retry; if persistent, the node is stuck — restart or replace it.
3. Unify providers: use one provider for both data feed and execution, or add cross-provider block-height monitoring.
4. Check node sync status (eth_syncing) and wait for catch-up before quoting.

Example fix

// before: execution endpoint lagging the feed
let exec_rpc = Provider::new(lagging_url);

// after: use a synced endpoint consistent with the feed
let exec_rpc = Provider::new(primary_feed_url);

let latest_block = exec_rpc.get_block_number().await?;
if profiler_block > latest_block {
    // execution endpoint lags; refresh or wait before quoting
    return Err("execution RPC behind data feed".into());
}

match client.get_pool_quote(pool).await {
    Ok(q) => q,
    Err(e) if e.to_string().contains("ahead of the latest block") => refresh_endpoint_and_retry(e).await,
    Err(e) => return Err(e),
}

When it happens

Trigger: Calling validate_quote_age with profiler_block > latest_block — i.e., the execution RPC's latest block number is behind the block height of the cached pool state/quote.

Common situations: Execution RPC on a lagging or rate-limited node while the data feed runs ahead; split providers (fast data-feed provider, slow execution provider); a node stuck syncing or on a different fork; clock-free block-height mismatch after a data-feed provider upgrade.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Failed to sync pool events: {e}
• Finalized block {} does not contain transaction {}
• Finalized execution transaction {tx_hash} no longer has a re
• Canonical head changed during signer-nonce replacement scan
• Finalized block {} changed from {} to {} before intent valid

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/a21bd644d4324df2. Report an issue: GitHub.