eth_getUncleByBlockNumberAndIndex

eth_getUncleByBlockNumberAndIndex returns the uncle block (also called an ommer) at a given position within a parent block. The parent block is identified by a 0x-prefixed hex block number or a named block tag, and the uncle is selected by its zero-based index in that block's uncle list. The returned value is a block header object — uncle headers are stored without their own transaction bodies, so the transactions and uncles arrays of the returned object are always empty.

Uncles are a proof-of-work artifact. They only ever appeared on pre-Merge Ethereum (blocks mined before the September 2022 transition to proof-of-stake). Since the Merge, no new uncles are produced, so for any post-Merge block this method always returns null. It remains useful for reading historical pre-Merge blocks that did include uncles.

If the parent block does not exist, or the uncle index is out of range for that block, the result is null rather than an error. Always handle the null case before reading fields off the result. To find how many uncles a block has before indexing into them, call eth_getUncleCountByBlockNumber.

Pass a two-element positional array.

A pre-Merge block that has an uncle at the requested index returns the uncle's header object:

For any post-Merge block, or when the block or index does not exist, the response is:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": null
}

See errors.md for the full error envelope and handling guidance.

JavaScript (fetch)

const res = await fetch("https://api.triport.io/v1/ethereum", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.TRIPORT_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    jsonrpc: "2.0",
    id: 1,
    method: "eth_getUncleByBlockNumberAndIndex",
    params: ["0xf4240", "0x0"],
  }),
});


const { result } = await res.json();
if (result === null) {
  console.log("no uncle at that index (or post-Merge block)");
} else {
  console.log("uncle", result.hash, "mined by", result.miner);
}

TypeScript SDK (@triport/sdk)

import { Triport } from "@triport/sdk";


const client = new Triport({ apiKey: process.env.TRIPORT_API_KEY! });


type UncleHeader = { number: string; hash: string; miner: string };


const uncle = await client.ethereum.request<UncleHeader | null>(
  "eth_getUncleByBlockNumberAndIndex",
  ["0xf4240", "0x0"],
);


console.log(uncle ? uncle.hash : "no uncle at that index");

Python (triport-sdk)

import os
from triport import Triport


client = Triport(api_key=os.environ["TRIPORT_API_KEY"])


uncle = client.ethereum.request(
    "eth_getUncleByBlockNumberAndIndex",
    ["0xf4240", "0x0"],
)


print(uncle["hash"] if uncle else "no uncle at that index")

• Post-Merge blocks always return null. Uncles are a proof-of-work concept; no uncles have been produced since the Merge. Use this method only against historical pre-Merge blocks.
• The returned object is a block header, not a full block: its transactions and uncles arrays are always empty.
• The uncle index is zero-based: 0x0 is the first uncle. Both the block parameter and the index are 0x-prefixed hex strings.
• An out-of-range index or a non-existent block returns result: null, not an error — check for null before reading fields.
• Numeric fields (number, difficulty, timestamp, …) are hex strings; convert with base 16 before arithmetic.
• eth_getUncleByBlockNumberAndIndex is available on the free tier (eth_read_rpc category). Rate limiting is RPS-per-tier with burst; there is no daily quota. A -32003 rate_limited error means you should back off and retry shortly.
• To count a block's uncles first, use eth_getUncleCountByBlockNumber. To select the parent block by hash instead of number, use eth_getUncleByBlockHashAndIndex.