Transaction {} (intent {}, {}, nonce {}) is still awaiting f

Error message

Transaction {} (intent {}, {}, nonce {}) is still awaiting finality; at most one transaction can be in flight

What it means

Raised when the in-flight slot holds a transaction that has been broadcast but is still awaiting finality (confirmation on chain). The client blocks any new transaction until the pending one reaches finality; the message identifies the tx hash, intent, purpose, and nonce.

Source

Thrown at crates/adapters/blockchain/src/execution/client.rs:1861

        router: Address,
        amount: U256,
    },
}

/// The single-in-flight limit error naming the transaction currently occupying the slot.
fn in_flight_limit_error(slot: &InFlightSlot) -> anyhow::Error {
    match slot {
        InFlightSlot::Preparing(purpose) => anyhow::anyhow!(
            "A {} transaction is being prepared; at most one transaction can be in flight",
            purpose.as_str()
        ),
        InFlightSlot::Recovering(recovery) => anyhow::anyhow!(
            "Execution intent {} ({}, nonce {}) retains signer ownership pending recovery; at most one transaction can be in flight",
            recovery.intent_id,
            recovery.purpose.as_str(),
            recovery.nonce
        ),
        InFlightSlot::AwaitingFinality(in_flight) => anyhow::anyhow!(
            "Transaction {} (intent {}, {}, nonce {}) is still awaiting finality; at most one transaction can be in flight",
            in_flight.tx_hash,
            in_flight.intent_id,
            in_flight.purpose.as_str(),
            in_flight.nonce
        ),
    }
}

/// Releases a pre-signature slot claim when the slot is still in the preparing state.
///
/// Aborted or failed preparation can leave a claim behind; because no signed transaction
/// exists for a preparing slot, releasing it cannot strand a broadcastable signature.
fn release_preparing_slot(in_flight: &Mutex<Option<InFlightSlot>>) {
    let mut slot = in_flight.lock();
    if matches!(*slot, Some(InFlightSlot::Preparing(_))) {
        *slot = None;
    }

View on GitHub (pinned to 18893faf8b)

Solutions

Wait for the pending transaction to finalize; poll its receipt or await the finality future before submitting again.
Speed up the stuck tx via a replacement with higher gas (same nonce) if miners are slow.
Increase submission interval or implement an outbound order queue in the strategy.
Verify RPC connectivity — a lagging node may delay finality detection.

Example fix

// before: submit during pending finality
client.submit_order(order_b)?; // tx 0xdef... still awaiting finality
// after: wait for finality
client.await_transaction_finality("0xdef...").await?;
client.submit_order(order_b)?;

Defensive patterns

Strategy: retry

Validate before calling

if let Some(tx) = client.pending_in_flight() { client.await_transaction_finality(tx.tx_hash).await?; }

Type guard

fn is_awaiting_finality(slot: &InFlightSlot) -> bool { matches!(slot, InFlightSlot::AwaitingFinality(_)) }

Try / catch

match client.submit_order(order) { Err(e) if e.to_string().contains("awaiting finality") => { wait_with_backoff().await; retry(order); } Ok(r) => r }

Prevention

Queue outbound orders until the previous tx finalizes
Use replacement transactions (same nonce, higher gas) for stuck txs
Monitor finality latency and alert on slow confirmations

When it happens

Trigger: Submitting a new transaction while a previously sent transaction (given by tx_hash) has not yet reached the configured finality depth/confirmations.

Common situations: Slow block times or low gas price making confirmation take longer than the strategy's submission cadence; high-frequency strategy loop outpacing chain finality; RPC lag reporting stale receipt status.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/5f15acdfa357c518. Report an issue: GitHub.