nautechsystems/nautilus_trader · error

validated proxy slot

Error message

validated proxy slot

What it means

While verifying a deployment manifest, `verify_deployment_manifest` parses the proxy's `storage_slot` string into a `B256` with `.expect("validated proxy slot")`. The manifest is pre-validated by `validate_config` (verification.rs:1291), which rejects any manifest whose `storage_slot` is not valid hex — so this `expect` is an internal invariant: it should be unreachable if every manifest passed through validation. Hitting it means a `BlockchainDeploymentManifest` reached the verifier without going through `validate_config`.

Source

Thrown at crates/adapters/blockchain/src/rpc/verification.rs:655

                VerificationOutcome::Unavailable(failure) => {
                    return VerificationOutcome::Unavailable(failure);
                }
                VerificationOutcome::Retryable(failure) => {
                    return VerificationOutcome::Retryable(failure);
                }
                VerificationOutcome::LocallyInvalid(failure) => {
                    return VerificationOutcome::LocallyInvalid(failure);
                }
            };

            if code.is_empty() || keccak256(&code) != expected_hash {
                return VerificationOutcome::Disagreement(
                    self.failure(VerificationRead::DeploymentIdentity),
                );
            }

            if let Some(proxy) = &contract.proxy {
                let slot = B256::from_str(&proxy.storage_slot).expect("validated proxy slot");
                let expected =
                    B256::from_str(&proxy.storage_value).expect("validated proxy storage value");
                match self.verify_storage(&address, &slot, block).await {
                    VerificationOutcome::Verified(verified) if verified.value == expected => {}
                    VerificationOutcome::Verified(_) => {
                        return VerificationOutcome::Disagreement(
                            self.failure(VerificationRead::DeploymentIdentity),
                        );
                    }
                    VerificationOutcome::Disagreement(failure) => {
                        return VerificationOutcome::Disagreement(failure);
                    }
                    VerificationOutcome::Unavailable(failure) => {
                        return VerificationOutcome::Unavailable(failure);
                    }
                    VerificationOutcome::Retryable(failure) => {
                        return VerificationOutcome::Retryable(failure);
                    }

View on GitHub (pinned to 18893faf8b)

Solutions

1. Run the manifest through `validate_config` before verification so invalid slots are rejected with a proper error.
2. Fix the `proxy.storage_slot` in the manifest to be a full 32-byte hex string (66 chars including 0x).
3. In your own code, parse the slot with `B256::from_str` first and return an error instead of relying on the panic.
4. Check the manifest source/generator for schema drift producing wrong-length slots.

Example fix

// before
let slot = B256::from_str(&proxy.storage_slot).expect("validated proxy slot");
// after
let slot = B256::from_str(&proxy.storage_slot)
    .map_err(|e| anyhow::anyhow!("invalid proxy storage_slot {:?}: {e}", proxy.storage_slot))?;

fn validate_proxy_slot(proxy: &ProxyInfo) -> Result<B256, String> {
    let s = proxy.storage_slot.trim();
    let hex = s.strip_prefix("0x").unwrap_or(s);
    if hex.len() != 64 || !hex.chars().all(|c| c.is_ascii_hexdigit()) {
        return Err(format!("storage_slot must be 32-byte hex, got {s:?}"));
    }
    B256::from_str(s).map_err(|e| e.to_string())
}

// Always funnel manifests through validate_config before verification
validate_config(&manifest).map_err(|e| anyhow::anyhow!("invalid manifest: {e}"))?;

When it happens

Trigger: Calling `verify_deployment_manifest` with a manifest whose `proxy.storage_slot` is not valid 32-byte hex (wrong length, missing 0x, non-hex characters) and that was never checked by `validate_config` — e.g. deserialized from an untrusted JSON file or built programmatically in tests.

Common situations: Hand-edited deployment manifest JSON with a malformed storage slot; a typo'd slot like a 20-byte address used instead of a 32-byte slot; constructing the manifest in tests bypassing the validation entry point; using a manifest from an older schema version.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• validated proxy storage value
• validated proxy target
• in-flight mutex poisoned
• wallet balance mutex poisoned
• instrument update lock poisoned

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/e10d2a361520af66. Report an issue: GitHub.