Invalid config type for BlockchainExecutionClientFactory. Ex

Error message

Invalid config type for BlockchainExecutionClientFactory. Expected `BlockchainExecutionClientConfig`, was {config:?}

What it means

BlockchainExecutionClientFactory.create downcasts the passed config to BlockchainExecutionClientConfig. This error fires when the supplied config object is a different type, so the downcast fails and the factory cannot build the execution client.

Source

Thrown at crates/adapters/blockchain/src/factories.rs:139

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

impl ExecutionClientFactory for BlockchainExecutionClientFactory {
    fn create(
        &self,
        trader_id: TraderId,
        name: &str,
        config: &dyn ClientConfig,
        cache: CacheView,
    ) -> anyhow::Result<Box<dyn ExecutionClient>> {
        let blockchain_execution_config = config
            .as_any()
            .downcast_ref::<BlockchainExecutionClientConfig>()
            .ok_or_else(|| {
                anyhow::anyhow!(
                    "Invalid config type for BlockchainExecutionClientFactory. Expected `BlockchainExecutionClientConfig`, was {config:?}"
                )
            })?;

        let core_execution_client = ExecutionClientCore::new(
            trader_id,
            ClientId::from(name),
            *BLOCKCHAIN_VENUE,
            OmsType::Netting,
            blockchain_execution_config.client_id,
            AccountType::Wallet,
            None,
            cache,
        );

        let client = BlockchainExecutionClient::new(
            core_execution_client,
            blockchain_execution_config.clone(),

View on GitHub (pinned to 18893faf8b)

Solutions

Pass a BlockchainExecutionClientConfig to the execution client factory
Verify the factory-to-config pairing in the node registration code (data vs execution not swapped)
Inspect the config's concrete type via its Debug output and correct it

Example fix

// before
let cfg = BlockchainDataClientConfig { .. };
execution_factory.create(trader_id, &cfg, ...)
// after
let cfg = BlockchainExecutionClientConfig { .. };
execution_factory.create(trader_id, &cfg, ...)

Defensive patterns

Strategy: type-guard

Validate before calling

if config.as_any().downcast_ref::<BlockchainExecutionClientConfig>().is_none() {
    panic!("execution client factory requires BlockchainExecutionClientConfig, got {:?}", config);
}

Type guard

fn is_execution_client_config(config: &dyn ClientConfig) -> bool {
    config.as_any().downcast_ref::<BlockchainExecutionClientConfig>().is_some()
}

Try / catch

let client = execution_factory.create(trader_id, &config, ...)
    .map_err(|e| anyhow::anyhow!("execution client factory rejected config: {e:#}"))?;

Prevention

Do not share one config struct between data and execution factories
Verify factory/config pairing whenever wiring a new node configuration
Use distinct config type names to avoid copy-paste confusion

When it happens

Trigger: Calling BlockchainExecutionClientFactory.create with a config that is not BlockchainExecutionClientConfig (e.g. a BlockchainDataClientConfig or another adapter's config).

Common situations: Mismatched factory/config pairing in node setup; swapped factories (data factory given the execution config or vice versa); config deserialized into the wrong concrete struct.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/947964bd2b0b3ee6. Report an issue: GitHub.