LiveNodeConfig.controller for importable controller '{}' req

Error message

LiveNodeConfig.controller for importable controller '{}' requires the python feature

What it means

Importable controllers are loaded via Python (Trader::add_controller_from_importable_config), which requires the crate's `python` feature. Building a live node whose config specifies a controller without that feature compiled in cannot load the controller and fails at build time.

Source

Thrown at crates/live/src/node/builder.rs:599

        let runner = AsyncRunner::new();
        runner.bind_senders();

        let socket_registry = SocketReconnectRegistry::default();

        let kernel = NautilusKernel::new_with_dependencies(
            self.name.clone(),
            self.config.clone(),
            NautilusKernelDependencies::default()
                .with_clock_factory(self.clock_factory.take())
                .with_event_store_factory(self.event_store_factory.take()),
        )?;
        #[cfg(feature = "python")]
        if let Some(controller) = self.config.controller.as_ref() {
            Trader::add_controller_from_importable_config(&kernel.trader, controller)?;
        }
        #[cfg(not(feature = "python"))]
        if let Some(controller) = self.config.controller.as_ref() {
            anyhow::bail!(
                "LiveNodeConfig.controller for importable controller '{}' requires the python feature",
                controller.controller_path
            );
        }

        self.install_external_msgbus_factory(&kernel)?;

        if let Some(external_egress) = self.external_msgbus_egress.take() {
            let config = self.config.msgbus.clone().unwrap_or_default();
            nautilus_common::msgbus::get_message_bus()
                .borrow_mut()
                .set_external_egress_config(external_egress, &config)?;
        }

        for (name, factory) in self.data_client_factories {
            if let Some(config) = self.data_client_configs.remove(&name) {
                log::debug!("Creating data client {name}");

View on GitHub (pinned to 18893faf8b)

Solutions

Rebuild with the `python` feature enabled (e.g. cargo build --features python).
Remove the controller entry from LiveNodeConfig if Python support is not needed.
Implement the controller natively in Rust instead of using an importable (Python) controller path.

Example fix

// before (Cargo.toml)
nautilus_live = { version = "..." }
// after
nautilus_live = { version = "...", features = ["python"] }

Defensive patterns

Strategy: validation

Validate before calling

if config.controller.is_some() && !cfg!(feature = "python") { /* controller unsupported in this build */ }

Try / catch

match node_build_result { Err(e) if e.to_string().contains("requires the python feature") => eprintln!("rebuild with --features python"), other => other? }

Prevention

Align build features between environments that share config files.
Add a startup assertion that python-dependent features match the binary's features.
Strip python-specific config entries when deploying Rust-only binaries.

When it happens

Trigger: LiveNodeConfig.controller = Some(...) (with a controller_path) while running a build of nautilus_live compiled without `--features python`, in LiveNodeBuilder::build.

Common situations: Deploying a Rust-only (no-Python) binary with a config copied from a Python setup; Cargo.toml missing the `python` feature; Docker image built without Python support but reusing an existing config file.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/9f05c95e5bfcb90e. Report an issue: GitHub.