{"record":{"id":"41332e37132cb735","repo":"nautechsystems/nautilus_trader","slug":"failed-to-parse-eth-getstorageat-response","errorCode":null,"errorMessage":"Failed to parse eth_getStorageAt response","messagePattern":"Failed to parse eth_getStorageAt response","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"crates/adapters/blockchain/src/rpc/http.rs","lineNumber":405,"sourceCode":"    #[allow(\n        dead_code,\n        reason = \"Used by the independent verification read inventory\"\n    )]\n    pub(crate) async fn get_storage_at(\n        &self,\n        address: &Address,\n        slot: &B256,\n        block: u64,\n    ) -> anyhow::Result<B256> {\n        let result: Option<String> = self\n            .execute_execution_rpc_call(\n                \"eth_getStorageAt\",\n                serde_json::json!([address, slot, block_parameter(Some(block))]),\n            )\n            .await?;\n        let value = result.ok_or_else(|| anyhow::anyhow!(\"eth_getStorageAt returned no result\"))?;\n        B256::from_str(&value)\n            .map_err(|_| anyhow::anyhow!(\"Failed to parse eth_getStorageAt response\"))\n    }\n\n    async fn get_code_with_block(\n        &self,\n        address: &Address,\n        block: Option<u64>,\n    ) -> anyhow::Result<Bytes> {\n        let result: Option<String> = self\n            .execute_execution_rpc_call(\n                \"eth_getCode\",\n                serde_json::json!([address, block_parameter(block)]),\n            )\n            .await?;\n        let hex_string = result.ok_or_else(|| anyhow::anyhow!(\"eth_getCode returned no result\"))?;\n        let stripped = hex_string.strip_prefix(\"0x\").unwrap_or(&hex_string);\n        let bytes = hex::decode(stripped)\n            .map_err(|e| anyhow::anyhow!(\"Failed to decode eth_getCode result: {e}\"))?;\n        Ok(Bytes::from(bytes))","sourceCodeStart":387,"sourceCodeEnd":423,"githubUrl":"https://github.com/nautechsystems/nautilus_trader/blob/18893faf8b356be3320add8de2f861b0b647cf06/crates/adapters/blockchain/src/rpc/http.rs#L387-L423","documentation":"After a successful `eth_getStorageAt` call, the returned string is parsed into a `B256` (32-byte fixed hash). If the string is not valid hex of appropriate length, this error is raised (note: the original parse error is discarded, only a static message is returned).","triggerScenarios":"Node returns a storage value that is not a 32-byte hex string — e.g. a short hex value without padding (some chains return 0x + fewer bytes), decimal output, or a value with unexpected formatting.","commonSituations":"Non-standard or modified node implementations (some L2s or private chains) returning unpadded or differently-encoded storage values.","solutions":["Verify the node returns a full 32-byte 0x-prefixed hex string for eth_getStorageAt","Use a compliant node (geth/erigon standard behavior) or update node version","If values are unpadded, left-pad them to 64 hex chars before parsing","Log the raw value to confirm its actual format"],"exampleFix":"// before: node returns unpadded value -> B256::from_str fails\nlet value = client.get_storage_at(&addr, slot, Some(block)).await?;\n// after: left-pad to 32 bytes when necessary\nlet raw = format!(\"0x{:0>64}\", raw_hex.trim_start_matches(\"0x\"));","handlingStrategy":"validation","validationCode":"fn is_b256_hex(s: &str) -> bool {\n    let body = s.strip_prefix(\"0x\").unwrap_or(s);\n    body.len() == 64 && body.chars().all(|c| c.is_ascii_hexdigit())\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Use standard node implementations that return 32-byte padded hex","Sanitize/left-pad storage values when integrating non-standard chains","Snapshot the raw response when first integrating a new chain","Keep node software up to date"],"tags":["rpc","hex-parsing","storage","response-parsing"],"backgroundTag":"invalid-argument-format","analyzedSha":"18893faf8b356be3320add8de2f861b0b647cf06","analyzedAt":"2026-09-08T20:49:34.690Z","contentChangedAt":"2026-09-08T20:49:34.690Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}