nautechsystems/nautilus_trader · error

Failed to serialize json `payload`: {e}

Error message

Failed to serialize json `payload`: {e}

What it means

serialize_payload's JSON branch converts the payload to serde_json::Value (with timestamp conversion) and encodes with serde_json::to_vec. This error wraps serde_json serialization failures — values that cannot be represented in JSON.

Source

Thrown at crates/infrastructure/src/redis/queries.rs:93

    /// # Errors
    ///
    /// Returns an error if serialization to the chosen encoding fails.
    pub fn serialize_payload<T: Serialize>(
        encoding: SerializationEncoding,
        payload: &T,
    ) -> anyhow::Result<Vec<u8>> {
        match encoding {
            SerializationEncoding::MsgPack => {
                let mut value = serde_json::to_value(payload)?;
                convert_timestamps(&mut value);
                rmp_serde::to_vec(&value)
                    .map_err(|e| anyhow::anyhow!("Failed to serialize msgpack `payload`: {e}"))
            }
            SerializationEncoding::Json => {
                let mut value = serde_json::to_value(payload)?;
                convert_timestamps(&mut value);
                serde_json::to_vec(&value)
                    .map_err(|e| anyhow::anyhow!("Failed to serialize json `payload`: {e}"))
            }
            SerializationEncoding::Sbe => {
                anyhow::bail!("SBE encoding is not supported for Redis cache payloads")
            }
            SerializationEncoding::Capnp => {
                anyhow::bail!("Cap'n Proto encoding is not supported for Redis cache payloads")
            }
        }
    }

    /// Deserializes the given byte slice `payload` into type `T` using the specified `encoding`.
    ///
    /// # Errors
    ///
    /// Returns an error if deserialization from the chosen encoding fails or converting to the target type fails.
    pub fn deserialize_payload<T: DeserializeOwned>(
        encoding: SerializationEncoding,
        payload: &[u8],

View on GitHub (pinned to 18893faf8b)

Solutions

  1. Validate/replace NaN and Infinity values in the payload before serialization.
  2. Use string-serializable map keys in the payload type.
  3. Confirm the type's Serialize impl produces JSON-compatible structures.
  4. If SBE/Capnp was intended, note those encodings are explicitly unsupported for Redis cache payloads.

Example fix

// before
let payload = Quote { bid: f64::INFINITY };
serialize_payload(SerializationEncoding::Json, &payload)?;
// after
let bid = if payload.bid.is_finite() { payload.bid } else { 0.0 };
serialize_payload(SerializationEncoding::Json, &Quote { bid })?;
Defensive patterns

Strategy: try-catch

Validate before calling

// ensure JSON compatibility before serializing
fn is_json_safe(v: &serde_json::Value) -> bool {
    match v {
        serde_json::Value::Number(n) => n.as_f64().map(|f| f.is_finite()).unwrap_or(true),
        serde_json::Value::Array(a) => a.iter().all(is_json_safe),
        serde_json::Value::Object(o) => o.values().all(is_json_safe),
        _ => true,
    }
}

Try / catch

match serialize_payload(SerializationEncoding::Json, &payload) {
    Ok(bytes) => write_to_redis(bytes),
    Err(e) if e.to_string().contains("Failed to serialize json") => {
        log::error!("payload not JSON-serializable: {e}");
    }
    Err(e) => return Err(e),
}

Prevention

When it happens

Trigger: Calling serialize_payload(SerializationEncoding::Json, payload) where serde_json::to_value/to_vec fails, e.g. payloads containing NaN/Infinity floats or non-string map keys.

Common situations: Domain values carrying NaN/Inf prices; maps keyed by non-string types; custom Serialize impls emitting JSON-illegal values.

Understand the failure class

Background: "JSON serialization failed", "not JSON serializable", "Failed to serialize": why JSON marshaling errors happen and how to fix them — this error's family across 46 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/0aad8883dd909b5a. Report an issue: GitHub.