Invalid config type for DeribitDataClientFactory. Expected D

Error message

Invalid config type for DeribitDataClientFactory. Expected DeribitDataClientConfig, was {config:?}

What it means

DeribitDataClientFactory::create requires the passed config object to be a DeribitDataClientConfig. The factory performs a downcast_ref::<DeribitDataClientConfig>() on the type-erased ClientConfig; when the downcast returns None, it raises this anyhow error including the debug representation of the config actually received. This guards against wiring a config of the wrong client type into the factory.

Source

Thrown at crates/adapters/deribit/src/factories.rs:83

impl Default for DeribitDataClientFactory {
    fn default() -> Self {
        Self::new()
    }
}

impl DataClientFactory for DeribitDataClientFactory {
    fn create(
        &self,
        name: &str,
        config: &dyn ClientConfig,
        _cache: CacheView,
        _clock: Rc<RefCell<dyn Clock>>,
    ) -> anyhow::Result<Box<dyn DataClient>> {
        let deribit_config = config
            .as_any()
            .downcast_ref::<DeribitDataClientConfig>()
            .ok_or_else(|| {
                anyhow::anyhow!(
                    "Invalid config type for DeribitDataClientFactory. Expected DeribitDataClientConfig, was {config:?}",
                )
            })?
            .clone();

        let client_id = ClientId::from(name);
        let client = DeribitDataClient::new(client_id, deribit_config)?;
        Ok(Box::new(client))
    }

    fn name(&self) -> &'static str {
        DERIBIT
    }

    fn config_type(&self) -> &'static str {
        "DeribitDataClientConfig"
    }
}

View on GitHub (pinned to 18893faf8b)

Solutions

Construct a DeribitDataClientConfig (with correct instrument, testnet flag, credentials) and pass that to the factory instead of the current config.
Check the config value printed in the message: its Debug type name tells you exactly which struct was passed; swap it for DeribitDataClientConfig.
If iterating a mixed config collection, match on config type and dispatch each config to its matching factory before calling create().

Example fix

// before
let config = DeribitExecutionClientConfig::new();
let client = DeribitDataClientFactory.create(name, Rc::new(config), cache, clock)?;
// after
let config = DeribitDataClientConfig::new(instrument_provider_config);
let client = DeribitDataClientFactory.create(name, Rc::new(config), cache, clock)?;

Defensive patterns

Strategy: type-guard

Validate before calling

let Some(cfg) = config.as_any().downcast_ref::<DeribitDataClientConfig>() else {
    return Err(anyhow::anyhow!("expected DeribitDataClientConfig, got {config:?}"));
};

Type guard

fn is_deribit_data_config(config: &dyn ClientConfig) -> bool {
    config.as_any().is::<DeribitDataClientConfig>()
}

Try / catch

match factory.create(name, config, cache, clock) {
    Ok(client) => client,
    Err(e) => { eprintln!("deribit data client init failed: {e:#}"); return Err(e); }
}

Prevention

Keep each config struct next to its factory call in the bootstrap code so the pairing is obvious.
In loops over configs, match on the concrete config type and route to the matching factory.
Unit-test the happy-path wiring of each client at startup (fail fast before live trading).

When it happens

Trigger: Calling DeribitDataClientFactory::create(name, config, ...) with a config whose concrete type is not DeribitDataClientConfig — e.g. a DeribitExecutionClientConfig, a config for another venue adapter, or any other object implementing the ClientConfig trait.

Common situations: Copying factory setup code from another exchange adapter and forgetting to swap the config type; constructing clients from a generic config registry/loop that iterates mixed configs; a refactor that renamed or split the config type so the old struct is still constructed.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/1c1a4791200365d9. Report an issue: GitHub.