Failed to send query index_order_clients to database message

Error message

Failed to send query index_order_clients to database message handler: {e}

What it means

index_order_clients batches (ClientOrderId, ClientId) claims into DatabaseQuery::IndexOrderClients and sends them over self.tx to the database message handler; a send failure is wrapped in this error. An empty claims slice returns Ok early, so the only failure is a closed channel — the handler task has been dropped. The mapping is never persisted when this fires.

Source

Thrown at crates/infrastructure/src/sql/cache.rs:1243

        client_order_id: ClientOrderId,
        position_id: PositionId,
    ) -> anyhow::Result<()> {
        let query = DatabaseQuery::IndexOrderPosition(client_order_id, position_id);
        self.tx.send(query).map_err(|e| {
            anyhow::anyhow!(
                "Failed to send query index_order_position to database message handler: {e}"
            )
        })
    }

    fn index_order_clients(&self, claims: &[(ClientOrderId, ClientId)]) -> anyhow::Result<()> {
        if claims.is_empty() {
            return Ok(());
        }

        let query = DatabaseQuery::IndexOrderClients(claims.to_vec());
        self.tx.send(query).map_err(|e| {
            anyhow::anyhow!(
                "Failed to send query index_order_clients to database message handler: {e}"
            )
        })
    }

    fn update_actor(
        &self,
        actor_id: &ActorId,
        _state: &AHashMap<String, Bytes>,
    ) -> anyhow::Result<()> {
        anyhow::bail!("update_actor not implemented for PostgreSQL cache adapter: {actor_id}")
    }

    fn update_strategy(
        &self,
        strategy_id: &StrategyId,
        _state: &AHashMap<String, Bytes>,
    ) -> anyhow::Result<()> {

View on GitHub (pinned to 18893faf8b)

Solutions

Confirm the cache handler task is alive before index updates
Rebuild the adapter if it was shut down; do not reuse closed instances
Fix the handler's original failure from logs
Treat this as critical in live trading: order→client mappings lost here affect later lookups

Defensive patterns

Strategy: try-catch

Try / catch

if let Err(e) = cache.index_order_clients(&claims) {
    tracing::error!("order-client indexing failed: {e:#}");
    return Err(e.into());
}

Prevention

Never reuse a cache adapter after its handler task has been dropped
Check handler liveness before batch index updates
Investigate any prior handler panic — it closes the channel for all later calls
Order shutdown: engine stops indexing, then adapter drops

When it happens

Trigger: Calling index_order_clients with a non-empty claims slice after the handler task exited (shutdown, abort, or handler init failure).

Common situations: Adapter shutdown racing with execution engine index updates; handler crash from a prior failed query; stale adapter references after reconnect.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/191b9ea2cbe09805. Report an issue: GitHub.