What causes "Failed to register Betfair cricket fatal task: {e}" in nautechsystems/nautilus_trader?

Inspect the inner `{e}` for the registration failure cause

Failed to register Betfair cricket fatal task: {e}

Error message

Failed to register Betfair cricket fatal task: {e}

What it means

Registering the cricket stream's fatal-error monitoring task failed; the underlying error `{e}` is re-wrapped. This watcher task detects fatal cricket-stream conditions and triggers reconnection/shutdown; connect aborts when it cannot be registered.

Source

Thrown at crates/adapters/betfair/src/data.rs:968

                        let cricket_socket_control =
                            self.cricket_socket_control.as_ref().map(Arc::clone);

                        self.session_tasks
                        .spawn(async move {
                            if cricket_fatal_rx.recv().await.is_some() {
                                log::error!(
                                    "Betfair cricket stream permanently disabled due to fatal error"
                                );
                                cricket_client.close().await;

                                if let Some(control) = cricket_socket_control {
                                    control.deregister();
                                }
                            }
                        })
                        .map_err(|e| {
                            anyhow::anyhow!("Failed to register Betfair cricket fatal task: {e}")
                        })?;

                        log::debug!("Betfair cricket stream connected");
                    }
                    Err(e) => {
                        log::warn!("Betfair cricket stream connect failed: {e}");

                        if let Some(control) = &self.cricket_socket_control {
                            control.deregister();
                        }
                        self.cricket_stream_client = None;
                    }
                }
            }

            let keep_alive_client = Arc::clone(&self.http_client);
            let keep_alive_stream = Arc::clone(self.stream_client.as_ref().unwrap());
            let keep_alive_race_stream = self.race_stream_client.as_ref().map(Arc::clone);

View on GitHub (pinned to 18893faf8b)

Solutions

Inspect the inner `{e}` for the registration failure cause
Avoid overlapping connect and disconnect calls on the same client
Retry connect so the cricket stream and fatal watcher register within the same task-group generation
If the cricket stream endpoint itself failed (logged as a warning), the fatal task registration should not be attempted — verify ordering

Defensive patterns

Strategy: try-catch

Validate before calling

// ensure no shutdown in progress before connect
if client.is_shutting_down() { return Err(anyhow::anyhow!("connect during shutdown")); }

Try / catch

match client.connect().await {
    Err(e) if e.to_string().contains("Failed to register Betfair cricket fatal task") => {
        log::error!("cricket fatal watcher not registered: {e:#}");
        // retry connect; ensure disconnect() isn't running concurrently
    }
    other => other,
}

Prevention

Avoid concurrent connect/disconnect on the same client
Finish prior teardowns before reconnecting
Retry connect to register the watcher within a single task-group generation
Monitor cricket-stream connect warnings independently of registration errors

When it happens

Trigger: connect() -> after spawning the cricket stream task, the registration's map_err wraps a spawn/registration failure. Usually because the TaskGroup or shutdown registry is closed/not open due to a concurrent shutdown, or the group generation ended before registration completed.

Common situations: Connect racing disconnect; reconnect loop registering tasks into an already-advancing generation; internal spawn failure in the task group.

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/4acb8e1c555e9fd6. Report an issue: GitHub.