nautechsystems/nautilus_trader · error

Failed to start Tardis task generation: {e}

Error message

Failed to start Tardis task generation: {e}

What it means

Raised in connect when tasks.start_generation() fails while preparing the Tardis client for a new connection. The task supervisor could not open a new task generation, so no WebSocket stream task can be registered.

Source

Thrown at crates/adapters/tardis/src/data.rs:521

    }

    async fn connect(&mut self) -> anyhow::Result<()> {
        if self.is_connected() && self.tasks.is_open() {
            return Ok(());
        }

        if self.config.options.is_empty() && self.config.stream_options.is_empty() {
            anyhow::bail!("Either replay `options` or `stream_options` must be provided");
        }

        if !self.tasks.is_open() {
            self.tasks
                .finish_shutdown(Duration::from_secs(1), Duration::from_secs(2))
                .await
                .map_err(|e| anyhow::anyhow!("Failed to terminate Tardis tasks: {e}"))?;
            self.tasks
                .start_generation()
                .map_err(|e| anyhow::anyhow!("Failed to start Tardis task generation: {e}"))?;
            self.cancellation_token = self.tasks.cancellation_token();
        }

        let is_stream_mode = self.is_stream_mode();
        let book_snapshot_output = self.config.book_snapshot_output.clone();
        let extract_bbo_as_quotes = self.config.extract_bbo_as_quotes;

        let http_client = TardisHttpClient::new(
            self.config
                .api_key
                .as_ref()
                .map(|value| value.expose_secret()),
            None,
            None,
            self.config.normalize_symbols,
            self.config
                .proxy_url
                .as_ref()

View on GitHub (pinned to 18893faf8b)

Solutions

1. Wait for the previous shutdown to fully complete before reconnecting.
2. Verify finish_shutdown succeeded (error 3693 not raised) in the same connect path.
3. Serialize connect/disconnect calls; do not overlap lifecycle transitions.
4. Reconstruct the client if its task set is permanently closed.

if let Err(e) = client.connect().await {
    if e.to_string().contains("Failed to start Tardis task generation") {
        // supervisor is closed: recreate the client rather than retrying
        client = TardisDataClient::new(config)?;
        client.connect().await?;
    } else { return Err(e); }
}

When it happens

Trigger: Calling connect on a task set that is closed or still mid-shutdown, so start_generation is rejected.

Common situations: Rapid disconnect/reconnect cycling; a previously failed finish_shutdown leaving the supervisor in a bad state; calling connect after the client was stopped permanently.

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

• std::mem::take(&mut self.shutdown_errors).join("; ")
• Binance Spot public JSON stream pool is shutting down
• No active WebSocket client
• WebSocket output receiver not available
• {context}: {}

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/88010dff05141b42. Report an issue: GitHub.