nautechsystems/nautilus_trader · error · anyhow::Error

Failed to start Bybit session generation: {e}

Error message

Failed to start Bybit session generation: {e}

What it means

connect() similarly restarts session task generation (WebSocket session workers). A failure starting that generation is wrapped with this message and aborts connect after pending tasks already succeeded.

Source

Thrown at crates/adapters/bybit/src/execution.rs:745

            return Ok(());
        }

        if !self.pending_tasks.is_open() || !self.session_tasks.is_open() {
            self.teardown_partial_connect().await?;
        }

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

        if !self.session_tasks.is_open() {
            self.await_session_tasks().await?;
            self.session_tasks
                .start_generation()
                .map_err(|e| anyhow::anyhow!("Failed to start Bybit session generation: {e}"))?;
        }
        let http_client = self.http_client.clone();
        let ws_private = self.ws_private.clone();
        let ws_trade = self.ws_trade.clone();
        let setup_guard =
            TaskGroupGuard::new(&[&self.session_tasks, &self.pending_tasks], move || {
                http_client.cancel_all_requests();
                ws_private.begin_shutdown();
                ws_trade.begin_shutdown();
            });

        let connect_result: anyhow::Result<()> = async {
            // Reset after a prior disconnect so REST calls are not short-circuited
            self.http_client.reset_cancellation_token();

            let product_types = self.product_types();

            if !self.core.instruments_initialized() {

View on GitHub (pinned to 18893faf8b)

Solutions

  1. Read the wrapped inner error for the root cause
  2. Instantiate a new execution client rather than reconnecting a dead one
  3. Keep connect/disconnect on the same runtime that created the tasks
  4. Verify WebSocket endpoints/credentials if the session setup itself fails
Defensive patterns

Strategy: try-catch

Try / catch

match client.connect().await {
    Ok(()) => {}
    Err(e) if e.to_string().contains("session generation") => {
        tracing::error!("session generation failed: {e}; recreating client");
        client = BybitExecutionClient::new(/* fresh deps */).await?;
        client.connect().await?;
    }
    Err(e) => return Err(e),
}

Prevention

When it happens

Trigger: Calling connect when session_tasks generation is closed and start_generation() errors, e.g. after runtime shutdown or corrupted task-group state.

Common situations: Reconnect flows after abrupt network loss or prior disconnect; reusing a client across different tokio runtimes.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/85ab0bfd9fef583f. Report an issue: GitHub.