nautechsystems/nautilus_trader · error

default `StrategyConfig` should be valid

Error message

default `StrategyConfig` should be valid

What it means

`Default for StrategyConfig` is implemented by building the config through `StrategyConfig::builder().build()` and `.expect`ing validity. The builder validates all constraints, so if the defaults ever become invalid the Default impl panics instead of returning an invalid config. This is an internal invariant: the library authors promise the default set of fields always passes validation.

Source

Thrown at crates/trading/src/strategy/config.rs:233

)]
#[cfg_attr(
    feature = "python",
    pyo3_stub_gen::derive::gen_stub_pyclass(module = "nautilus_trader.trading")
)]
pub struct ImportableStrategyConfig {
    /// The fully qualified name of the Strategy class.
    pub strategy_path: String,
    /// The fully qualified name of the Strategy config class.
    pub config_path: String,
    /// The strategy configuration as a dictionary.
    pub config: HashMap<String, serde_json::Value>,
}

impl Default for StrategyConfig {
    fn default() -> Self {
        Self::builder()
            .build()
            .expect("default `StrategyConfig` should be valid")
    }
}

#[cfg(test)]
mod tests {
    use rstest::rstest;
    use strum::IntoEnumIterator;

    use super::*;

    #[rstest]
    fn test_default_config_is_valid() {
        assert!(StrategyConfig::builder().build().is_ok());
    }

    #[rstest]
    fn test_zero_market_exit_interval_rejected() {
        let result = StrategyConfig::builder().market_exit_interval_ms(0).build();

View on GitHub (pinned to 18893faf8b)

Solutions

1. If you hit this in a released build, report it as a bug — the shipped defaults must validate
2. If you modified defaults or validation in a fork, align the default field values with the builder's validation constraints
3. Bypass `Default` and construct via `StrategyConfig::builder()` with explicit valid values

Example fix

// before
let config = StrategyConfig::default();
// after: explicit validated construction
let config = StrategyConfig::builder()
    .some_field(valid_value)
    .build()
    .expect("explicit StrategyConfig should be valid");

// Verify the default config validates without panicking (compile-time habit / test)
let cfg = StrategyConfig::builder().build();
assert!(cfg.is_ok(), "default StrategyConfig must validate");

// Avoid .default() in contexts where a panic is unacceptable; build explicitly
let config = StrategyConfig::builder().build()
    .map_err(|e| MyError::Config(e.to_string()))?;

When it happens

Trigger: Calling `StrategyConfig::default()` (directly or via `Default::default()`) when the crate's default field values violate a builder validation rule — normally only after a code change makes defaults inconsistent with validation.

Common situations: Users should essentially never hit this; it surfaces during crate development/downstream forks after editing default values or validation rules so they disagree.

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

• Close command should not be drained
• Flush command should not be drained
• Invalid factory address for DEX {name} on chain {chain} for
• Order invariant violated: first event must be OrderInitializ
• API key is valid UTF-8

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/f9ebe38627c188fc. Report an issue: GitHub.