nautechsystems/nautilus_trader · error

RPC parsing of initialize event is not defined in this dex

Error message

RPC parsing of initialize event is not defined in this dex: {}:{}

What it means

This error is raised by `DexExtended::parse_initialize_event_rpc` when the DEX instance has no RPC-based initialize-event parser registered (`parse_initialize_event_rpc_fn` is `None`). Each DEX adapter opts in to which events it can parse from raw RPC logs; this DEX simply does not implement an initialize-event RPC parser. The message includes the chain and DEX name so you know which adapter lacks the capability.

Solutions

  1. Register the initialize RPC parser on the DEX before use: supply `parse_initialize_event_rpc_fn: Some(<dex-specific parse fn>)` wherever the `DexExtended` is constructed.
  2. Check whether the DEX supports RPC initialize parsing before calling (inspect `parse_initialize_event_rpc_fn.is_some()` or an equivalent capability helper) and skip/log otherwise.
  3. If the initialize event is not needed for this DEX, stop routing Initialize logs to this parser and filter them at the log-dispatch layer.
  4. If you believe the DEX should support it, verify you are using the correct adapter module for that DEX (e.g. a full Uniswap-V3-compatible adapter) rather than a minimal one.

Example fix

// before
let dex = DexExtended::new(chain, name, address, ...); // parser fns default to None
let ev = dex.parse_initialize_event_rpc(&log)?; // bails
// after
let dex = DexExtended::new(chain, name, address, ...)
    .with_parse_initialize_event_rpc_fn(parsing::uniswap_v3::parse_initialize_event_rpc);
let ev = dex.parse_initialize_event_rpc(&log)?;
Defensive patterns

Strategy: fallback

Validate before calling

// check capability before calling
if dex.parse_initialize_event_rpc_fn.is_none() {
    // skip or use the non-RCP (hypersync) path
    tracing::debug!("initialize rpc parsing unsupported");
}

Type guard

fn supports_initialize_rpc(dex: &DexExtended) -> bool {
    dex.parse_initialize_event_rpc_fn.is_some()
}

Try / catch

match dex.parse_initialize_event_rpc(&log) {
    Ok(ev) => handle_initialize(ev),
    Err(e) if e.to_string().contains("not defined in this dex") => {
        tracing::debug!("no initialize rpc parser; skipping");
    }
    Err(e) => return Err(e),
}

Prevention

When it happens

Trigger: Calling `dex.parse_initialize_event_rpc(&log)` on a `DexExtended` that was constructed without setting `parse_initialize_event_rpc_fn` (e.g. a DEX whose parser registry only covers swap/mint/burn events, or one built via a generic constructor that leaves the optional fn unset).

Common situations: Indexing a new chain/DEX where the adapter wiring only registered stream/Hypersync parsers but not RPC parsers; a DEX built through a builder or config path that omits the initialize RPC parser; calling the RPC parse API on a DEX that only supports a subset of Uniswap-V3-style events.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/b54965fb38db75dd. Report an issue: GitHub.

Appendix: source

Thrown at crates/adapters/blockchain/src/exchanges/extended.rs:509

        } else {
            anyhow::bail!(
                "RPC parsing of burn event is not defined in this dex: {}:{}",
                self.dex.chain,
                self.dex.name
            )
        }
    }

    /// Parses an initialize event from an RPC log.
    ///
    /// # Errors
    ///
    /// Returns an error if the DEX does not have an RPC initialize event parser defined or if parsing fails.
    pub fn parse_initialize_event_rpc(&self, log: &RpcLog) -> anyhow::Result<InitializeEvent> {
        if let Some(parse_fn) = &self.parse_initialize_event_rpc_fn {
            parse_fn(self.dex.clone(), log)
        } else {
            anyhow::bail!(
                "RPC parsing of initialize event is not defined in this dex: {}:{}",
                self.dex.chain,
                self.dex.name
            )
        }
    }

    /// Parses a collect event from an RPC log.
    ///
    /// # Errors
    ///
    /// Returns an error if the DEX does not have an RPC collect event parser defined or if parsing fails.
    pub fn parse_collect_event_rpc(&self, log: &RpcLog) -> anyhow::Result<CollectEvent> {
        if let Some(parse_fn) = &self.parse_collect_event_rpc_fn {
            parse_fn(self.dex.clone(), log)
        } else {
            anyhow::bail!(
                "RPC parsing of collect event is not defined in this dex: {}:{}",

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