nautechsystems/nautilus_trader · error

Failed to start Coinbase session generation: {e}

Error message

Failed to start Coinbase session generation: {e}

What it means

Raised in CoinbaseExecutionClient::connect when TaskGroup::start_generation() fails while re-establishing the user WebSocket session after closing a stale one. It wraps the underlying task-group error (e.g. a generation is already running or the group was shut down) into an anyhow error that aborts the connect flow.

Source

Thrown at crates/adapters/coinbase/src/execution.rs:388

        }

        if !self.pending_tasks.is_open() {
            self.await_pending_tasks().await?;
            self.pending_tasks
                .start_generation()
                .map_err(|e| anyhow::anyhow!("Failed to start Coinbase task generation: {e}"))?;
        }

        if !self.session_tasks.is_open() || !self.session_tasks.is_empty() {
            self.abort_session_tasks();
            self.ws_user
                .disconnect()
                .await
                .context("failed to close stale Coinbase user WebSocket")?;
            self.await_session_tasks().await?;
            self.session_tasks
                .start_generation()
                .map_err(|e| anyhow::anyhow!("Failed to start Coinbase session generation: {e}"))?;
        }
        let ws_user = self.ws_user.clone();
        let setup_guard =
            TaskGroupGuard::new(&[&self.session_tasks, &self.pending_tasks], move || {
                ws_user.begin_shutdown();
            });

        // If the underlying WS is still alive from a prior stop() that did not
        // explicitly disconnect, tear it down before reconnecting. The
        // in-handler signal path can race with the Disconnect command, leaving
        // the inner connection_mode stale even after disconnect().await, so
        // we rebuild the client outright to guarantee clean cmd_tx/out_rx
        // pairs and a fresh signal.
        if self.ws_user.is_active() || self.ws_user.is_reconnecting() {
            log::debug!("Tearing down stale user WS before reconnect");
            self.ws_user
                .disconnect()
                .await

View on GitHub (pinned to 18893faf8b)

Solutions

1. Ensure disconnect() is fully awaited before calling connect() again so the previous session generation ends.
2. Check the wrapped {e} source for 'already started' style TaskGroup errors and serialize your connect calls.
3. Await await_session_tasks()/join on prior session tasks before reconnecting.
4. If the client is permanently stopped, create a fresh client instance instead of reconnecting.

Example fix

// before
client.connect().await?;
// after (serialize reconnects)
if client.is_connected() { client.disconnect().await?; }
client.connect().await?;

if client_is_connected() { tokio::time::timeout(Duration::from_secs(10), client.disconnect()).await.expect("disconnect timed out"); }

fn can_start_generation(joined: bool, stopped: bool) -> bool { !joined && !stopped }

match client.connect().await {
    Ok(_) => {},
    Err(e) if e.to_string().contains("session generation") => { /* serialize reconnect: wait for prior tasks, then retry once */ }
    Err(e) => return Err(e),
}

When it happens

Trigger: Calling connect() on a Coinbase execution client whose session_tasks TaskGroup is already in a running generation, or in a state (stopping/stopped) that refuses a new generation start.

Common situations: Double-connecting the same client (e.g. reconnect logic racing with an existing connection), restarting a live node without awaiting the prior disconnect, or framework lifecycle code calling connect twice.

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

• Failed to terminate Hyperliquid execution session tasks: {e}
• subscription state lock poisoned
• InstrumentState channel requires kind and currency parameter
• std::mem::take(&mut self.shutdown_errors).join("; ")
• noid '{}' does not match new order oid '{}'

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/1674ef2f8752da62. Report an issue: GitHub.