nautechsystems/nautilus_trader · error

Failed to parse {method} response

Error message

Failed to parse {method} response

What it means

Raised when the raw HTTP body of an execution RPC response cannot be deserialized into the expected `RpcNodeHttpResponse<T>` envelope. The library requires a JSON body matching the JSON-RPC response shape; anything else (HTML, empty body, truncated JSON) fails parsing.

Source

Thrown at crates/adapters/blockchain/src/rpc/http.rs:337

            "id": 1,
            "method": method,
            "params": params,
        });

        let bytes = self
            .send_rpc_request(request, Some(EXECUTION_RPC_TIMEOUT_SECS))
            .await
            .map_err(|e| match e {
                BlockchainRpcClientError::ClientError(message)
                    if message.contains("redirect response rejected") =>
                {
                    anyhow::anyhow!("{method} redirect rejected")
                }
                _ => anyhow::anyhow!("{method} request failed"),
            })?;

        let parsed = serde_json::from_slice::<RpcNodeHttpResponse<T>>(bytes.as_ref())
            .map_err(|_| anyhow::anyhow!("Failed to parse {method} response"))?;

        if parsed.jsonrpc.is_none()
            && let (Some(code), Some(_message)) = (parsed.code, parsed.message)
        {
            anyhow::bail!("{method} RPC error {code}");
        }

        if let Some(error) = parsed.error {
            anyhow::bail!("{method} RPC error {}", error.code);
        }

        Ok(parsed.result)
    }

    /// Returns the chain ID reported by the RPC node via `eth_chainId`.
    ///
    /// # Errors
    ///

View on GitHub (pinned to 18893faf8b)

Solutions

1. Inspect the raw response body (curl the endpoint with the same method) to see what is returned
2. Point the client at the correct JSON-RPC path rather than a web/REST endpoint
3. Disable/adjust proxy error-interception pages for the RPC route
4. Check provider rate limits and authentication headers

Example fix

// before: hitting wrong path
let url = "https://provider.example.com/v1/mainnet";
// after: correct JSON-RPC endpoint
let url = "https://provider.example.com/v1/mainnet/rpc";

// ensure endpoint returns JSON-RPC envelope before use:
// curl -s -X POST $URL -d '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}' \
//   | python -c 'import json,sys; json.load(sys.stdin)'

match client.chain_id().await {
    Err(e) if e.to_string().contains("Failed to parse") => {
        // endpoint returned non-JSON; switch URL or inspect raw body
    }
    other => other,
}

When it happens

Trigger: The node or an intermediary returns a non-JSON body for chain_id, get_storage_at, get_code, or get_transaction_count calls — e.g. an HTML error page from a gateway, an empty 200 response, or malformed JSON.

Common situations: Reverse proxy (nginx/Cloudflare) intercepting errors, hitting a REST endpoint instead of the JSON-RPC endpoint, or rate-limit pages from public RPC providers.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• from_json not implemented for {}
• Failed to parse eth call response: {e} Raw response: {previe
• Failed to parse balance hex string '{hex_string}': {e}
• Failed to parse eth_getStorageAt response
• Failed to parse eth_call response

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/93646cfa3bf63bbd. Report an issue: GitHub.