Invalid factory address for DEX {name} on chain {chain} for

Error message

Invalid factory address for DEX {name} on chain {chain} for factory address {factory}: {e}

What it means

AmmsDex/DEX constructor validates the factory contract address with validate_address() and panics if the hex string is not a valid address. The panic includes the DEX name, chain, offending address, and the underlying validation error so the misconfiguration is immediately obvious.

Source

Thrown at crates/model/src/defi/dex.rs:204

        name: DexType,
        factory: &str,
        factory_creation_block: u64,
        amm_type: AmmType,
        pool_created_event: &str,
        swap_event: &str,
        mint_event: &str,
        burn_event: &str,
        collect_event: &str,
    ) -> Self {
        let encoded_pool_created_event =
            hex::encode_prefixed(keccak256(pool_created_event.as_bytes()));
        let encoded_swap_event = hex::encode_prefixed(keccak256(swap_event.as_bytes()));
        let encoded_mint_event = hex::encode_prefixed(keccak256(mint_event.as_bytes()));
        let encoded_burn_event = hex::encode_prefixed(keccak256(burn_event.as_bytes()));
        let encoded_collect_event = hex::encode_prefixed(keccak256(collect_event.as_bytes()));
        let factory_address = match validate_address(factory) {
            Ok(address) => address,
            Err(e) => panic!(
                "Invalid factory address for DEX {name} on chain {chain} for factory address {factory}: {e}"
            ),
        };
        Self {
            chain,
            name,
            factory: factory_address,
            factory_creation_block,
            pool_created_event: encoded_pool_created_event.into(),
            initialize_event: None,
            swap_created_event: encoded_swap_event.into(),
            mint_created_event: encoded_mint_event.into(),
            burn_created_event: encoded_burn_event.into(),
            collect_created_event: encoded_collect_event.into(),
            flash_created_event: None,
            fee_protocol_update_event: None,
            fee_protocol_collect_event: None,
            amm_type,

View on GitHub (pinned to 18893faf8b)

Solutions

Fix the factory address in your configuration to a full 0x-prefixed 40-hex-character address
Run validate_address(factory) yourself before constructing the DEX to fail early with a clean message
Verify the address is the correct contract for the specified chain (e.g. via an explorer)

Example fix

// before
let dex = AmmDex::new(chain, "UniswapV3", "0x1f9843..."); // truncated -> panic
// after
let factory = "0x1F98431c8aD98523631AE4a59f267346ea31F984";
validate_address(factory).expect("valid factory address");
let dex = AmmDex::new(chain, "UniswapV3", factory);

Defensive patterns

Strategy: validation

Validate before calling

// Validate before constructing the DEX
fn valid_factory(factory: &str) -> bool {
    factory.len() == 42 && factory.starts_with("0x") && factory[2..].chars().all(|c| c.is_ascii_hexdigit())
}

Type guard

fn is_hex_address(s: &str) -> bool {
    s.len() == 42 && s.starts_with("0x") && s[2..].chars().all(|c| c.is_ascii_hexdigit())
}

Try / catch

assert!(is_hex_address(factory), "bad factory address: {factory}");
let dex = AmmDex::new(chain, name, factory);

Prevention

Store factory addresses as validated constants, not free-form config strings
Cross-check addresses against a block explorer for the target chain
Run validate_address on all addresses at config load time

When it happens

Trigger: Constructing a DEX (AmmDex::new) with a factory address that is not a valid 20-byte hex address (wrong length, missing 0x, non-hex characters, or a checksum/shape error from validate_address).

Common situations: Hardcoded config files with a truncated or malformed address; copying a factory address from docs of a different network; placeholder addresses left in a config; config values typed as ENS names instead of hex addresses.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/a3439adf98f3c4d8. Report an issue: GitHub.