nautechsystems/nautilus_trader · error · anyhow::Error

Execution client {client_id} disappeared during startup reco

Error message

Execution client {client_id} disappeared during startup reconciliation

What it means

After reconciling an execution client's mass status, the node re-checks that the client is still registered in the exec engine (anyhow::ensure! with get_client(&client_id).is_some()). If it vanished — for example a disconnect or adapter failure occurred while reconciliation was awaited — startup aborts with this error. This is a defensive invariant: reconciliation results must still map to a live registered client.

Source

Thrown at crates/live/src/node/mod.rs:908

                )
            })?;

            match mass_status_result {
                Ok(Some(mass_status)) => {
                    log_info!(
                        "Reconciling ExecutionMassStatus for {}",
                        client_id,
                        color = LogColor::Blue
                    );

                    let exec_engine_rc = self.kernel.exec_engine.clone();

                    let result = self
                        .exec_manager
                        .reconcile_execution_mass_status(mass_status, exec_engine_rc)
                        .await;

                    anyhow::ensure!(
                        self.kernel
                            .exec_engine
                            .borrow()
                            .get_client(&client_id)
                            .is_some(),
                        "Execution client {client_id} disappeared during startup reconciliation",
                    );

                    if result.events.is_empty() {
                        log_info!(
                            "Reconciliation for {} succeeded",
                            client_id,
                            color = LogColor::Blue
                        );
                    } else {
                        log::info!(
                            color = LogColor::Blue as u8;
                            "Reconciliation for {} processed {} events",

View on GitHub (pinned to 18893faf8b)

Solutions

Investigate adapter/venue logs to find why the client disconnected during reconciliation (session expiry, network drop) and fix the root cause.
Retry startup once connections are stable; the client should remain registered throughout reconciliation.
Update adapter credentials/session handling (auto-reconnect, keepalive) so clients are not deregistered mid-startup.
Check adapter version for known disconnect/deregistration bugs and upgrade.

Defensive patterns

Strategy: validation

Validate before calling

// Before reconciliation, confirm client is registered and connection is healthy
let engine = node.kernel().exec_engine.borrow();
assert!(engine.get_client(&client_id).is_some(), "client {client_id} must be registered before reconciliation");
assert!(engine.get_client(&client_id).unwrap().is_connected(), "client {client_id} not connected");

Try / catch

match node.start().await {
    Err(e) if e.to_string().contains("disappeared during startup reconciliation") => {
        // reconnect/inspect adapter stability, then retry startup
    }
    other => other?,
}

Prevention

Enable adapter auto-reconnect and session keepalive
Ensure credentials/session TTL outlasts startup reconciliation
Run nodes on stable network links; avoid VPN drops mid-startup
Check adapter changelogs for disconnect-during-report bugs

When it happens

Trigger: In perform_startup_reconciliation, after reconcile_execution_mass_status completes, self.kernel.exec_engine.borrow().get_client(&client_id) returns None (mod.rs:908-915), i.e. the client was removed between mass-status generation and post-reconcile validation.

Common situations: Broker WebSocket disconnects mid-reconciliation and the adapter deregisters the client; venue session expires during long mass-status generation; flaky network drops the client while its report is being processed.

Understand the failure class

Background: "Not found" and "does not exist" errors: why "Task not found", "No such folder", and "Can't find" fire when a lookup comes back empty — this error's family across 14 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/622038cf7531aac9. Report an issue: GitHub.