eth_getUncleByBlockNumberAndIndex - Arbitrum

Example code for the eth_getUncleByBlockNumberAndIndex JSON RPC method. Сomplete guide on how to use eth_getUncleByBlockNumberAndIndex JSON RPC in GetBlock Web3 documentation.

This method returns information about an uncle block using the parent block hash and the uncle index.

Arbitrum does not produce uncle blocks, so this method always returns null, but it exists for full EVM compatibility.

Parameters

Parameter

Type

Required

Description

block_hash

string

yes

The hash of the block whose uncle is being requested. Must be a 32 byte hex string prefixed with 0x.

uncle_index

string

yes

The index of the uncle in the block. Must be a hex number like "0x0".

Request

curl --location 'https://go.getblock.us/<ACCESS_TOKEN>' \
--header 'Content-Type: application/json' \
--data '{
   "jsonrpc": "2.0",
   "method": "eth_getUncleByBlockHashAndIndex",
  "params": [
    "0x4cc1439cb36e8e984ed8c3562b222db19fac331ab79d9e90dc351325289621ea",
    "0x0"
  ],
    "id": "getblock.io"
}'

import axios from 'axios'
let data = JSON.stringify({
    "jsonrpc": "2.0",
     "method": "eth_getUncleByBlockHashAndIndex",
  "params": [
    "0x4cc1439cb36e8e984ed8c3562b222db19fac331ab79d9e90dc351325289621ea",
    "0x0"
  ],
    "id": "getblock.io"
};

let config = {
  method: "post",
  maxBodyLength: Infinity,
  url: "https://go.getblock.us/<ACCESS_TOKEN>",
  headers: {
    "Content-Type": "application/json",
  },
  data: data,
};

axios
  .request(config)
  .then((response) => {
    console.log(JSON.stringify(response.data));
  })
  .catch((error) => {
    console.log(error);
  });

import requests
import json

url = "https://go.getblock.us/<ACESS_TOKEN>"

payload = json.dumps({
   "jsonrpc": "2.0",
     "method": "eth_getUncleByBlockHashAndIndex",
  "params": [
    "0x4cc1439cb36e8e984ed8c3562b222db19fac331ab79d9e90dc351325289621ea",
    "0x0"
  ],
    "id": "getblock.io"
})
headers = {
  'Content-Type': 'application/json'
}

response = requests.request("POST", url, headers=headers, data=payload)

print(response.text)

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = reqwest::Client::builder()
        .build()?;

    let mut headers = reqwest::header::HeaderMap::new();
    headers.insert("Content-Type", "application/json".parse()?);

    let data = r#"{
   "jsonrpc": "2.0",
    "method": "eth_getUncleByBlockHashAndIndex",
  "params": [
    "0x4cc1439cb36e8e984ed8c3562b222db19fac331ab79d9e90dc351325289621ea",
    "0x0"
  ],
    "id": "getblock.io"
}"#;

    let json: serde_json::Value = serde_json::from_str(&data)?;

    let request = client.request(reqwest::Method::POST, "https://go.getblock.us/<ACCESS_TOKEN>")
        .headers(headers)
        .json(&json);

    let response = request.send().await?;
    let body = response.text().await?;

    println!("{}", body);

    Ok(())
}

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": null
}

Reponse Parameter Definition

Field

Description

number

Block number of the uncle

hash

Hash of the uncle block

parentHash

Parent block hash

miner

Miner address

difficulty

Difficulty of uncle block

gasLimit

Gas limit

gasUsed

Gas used

timestamp

Timestamp

uncles

Always empty

But again, on Arbitrum the value is always null.

Use case

Even though Arbitrum does not have uncle blocks, the method helps developers by:

Maintaining compatibility with Ethereum RPC tooling
Supporting indexers that expect standard EVM methods
Allowing multi-chain dashboards to run a single RPC workflow
Preventing errors in systems that automatically query all uncle endpoints

Error handling

Status Code

Error Message

Cause

403

Forbidden

Missing or invalid ACCESS_TOKEN.

-32602

Invalid argument

Invalid block hash
Invalid index

Integration with Web3

The eth_getUncleByBlockHashAndIndex method helps developers to:

Build tools compatible with Ethereum and Arbitrum
Implement universal RPC logic across multiple chains
Handle uncle queries gracefully even when none exist
Prevent backend crashes due to missing RPC behavior

import { ethers } from "ethers";
const RPC_URL = "https://go.getblock.us/<ACCESS_TOKEN>";
const provider = new ethers.JsonRpcProvider(RPC_URL);
async function Call() {
  try {
     const result = await provider.send("eth_getUncleByBlockHashAndIndex",
  [
    "0x4cc1439cb36e8e984ed8c3562b222db19fac331ab79d9e90dc351325289621ea",
    "0x0"
  ]);    
console.log("The result:", result);
    return result;
  } catch (error) {
    console.error("The error:", error);
    throw error;
  }
}

import { createPublicClient, http } from 'viem';
import { arbitrum } from 'viem/chains';

// Create Viem client with GetBlock
const client = createPublicClient({
  chain: arbitrum,
  transport: http('https://go.getblock.us/<ACCESS_TOKEN>'),
});

// Using the method through Viem
async function Call() {
    try {
        // Method-specific Viem implementation
        const result = await client.request({
         method: "eth_getUncleByBlockHashAndIndex",
         params: [
    "0x4cc1439cb36e8e984ed8c3562b222db19fac331ab79d9e90dc351325289621ea",
    "0x0"
  ]});
        console.log('Result:', result);
        return result;
    } catch (error) {
        console.error('Viem Error:', error);
        throw error;
    }
}

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