nautechsystems/nautilus_trader · error · anyhow::Error

Binance instrument filter

Error message

Binance instrument filter {name:?} must be a non-empty string or array of strings

What it means

Each Binance instrument provider filter value must be either a non-empty string or a non-empty array of non-empty strings. validate_filter_strings() rejects values of any other JSON type (number, bool, object, null) or empty/whitespace-only strings. This ensures filter values serialize into valid REST query parameters.

Solutions

Provide a non-empty string value for the filter, e.g. symbols="BTCUSDT".
Provide a non-empty array of non-empty strings, e.g. symbols=["BTCUSDT","ETHUSDT"] with all entries trimmed non-empty.
Remove the filter entirely if you do not intend to filter.
Trim and check user-supplied filter values before constructing the config.

Example fix

// before
filters.insert("symbols", json!([]));
// after
filters.insert("symbols", json!(["BTCUSDT", "ETHUSDT"]));

Defensive patterns

Strategy: validation

Validate before calling

fn filter_value_ok(v: &serde_json::Value) -> bool {
    match v {
        serde_json::Value::String(s) => !s.trim().is_empty(),
        serde_json::Value::Array(a) => {
            !a.is_empty()
                && a.iter().all(|x| x.as_str().is_some_and(|s| !s.trim().is_empty()))
        }
        _ => false,
    }
}

Prevention

Never insert empty strings or empty arrays as filter values; omit the filter instead.
Normalize/trim values loaded from env vars before building filters.
Store symbol lists as Vec<String> in your own config and serialize only when non-empty.

When it happens

Trigger: Setting an instrument filter value to an empty string (""), an empty array ([]), a non-string type (number/bool/object), or an array containing empty strings, then calling validate().

Common situations: Environment-variable-driven config where an optional filter resolves to an empty string; deserialized JSON where the filter value was a number; building filters programmatically with an uninitialized empty list.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/df1a7898f2bb7e63. Report an issue: GitHub.

Appendix: source

Thrown at crates/adapters/binance/src/config.rs:138

        }

        Ok(())
    }
}

fn validate_filter_strings(name: &str, value: &serde_json::Value) -> anyhow::Result<()> {
    let valid = match value {
        serde_json::Value::String(value) => !value.trim().is_empty(),
        serde_json::Value::Array(values) => {
            !values.is_empty()
                && values
                    .iter()
                    .all(|value| value.as_str().is_some_and(|value| !value.trim().is_empty()))
        }
        _ => false,
    };

    anyhow::ensure!(
        valid,
        "Binance instrument filter {name:?} must be a non-empty string or array of strings"
    );
    Ok(())
}

/// Spot market-data transport mode.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(
    feature = "python",
    pyo3::pyclass(module = "nautilus_trader.adapters.binance", eq, from_py_object)
)]
#[cfg_attr(
    feature = "python",
    pyo3_stub_gen::derive::gen_stub_pyclass_enum(module = "nautilus_trader.adapters.binance")
)]
pub enum BinanceSpotMarketDataMode {
    #[default]

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