eth_getUncleByBlockHashAndIndex

eth_getUncleByBlockHashAndIndex returns the header of an uncle (ommer) block at a given index inside the block identified by a hash. The method is kept for Ethereum JSON-RPC compatibility on Polygon — the PoS chain whose native token is MATIC and whose endpoint is https://polygon.therpc.io/YOUR_API_KEY (chain ID 137, 0x89). It is important to understand that Polygon's Bor/Heimdall Proof-of-Stake design never forks into uncle blocks the way Ethereum's old Proof-of-Work chain did, so on Polygon this call effectively always returns null. It remains available so tooling written against the standard Ethereum interface does not break.

Use cases

• On Proof-of-Work chains this method underpins uncle-reward calculations for historical mining analysis; on Polygon PoS no uncle rewards exist, so it returns null.
• Elsewhere it is used to measure historical uncle rates as a proxy for network latency and block-production competition — a metric that simply does not apply to Polygon's checkpointed PoS blocks.
• It can retrieve uncle header fields for blockchain research, but on Polygon the productive equivalent is reading the canonical header with eth_getBlockByHash instead.

Parameters

Response

Example request

1curl https://polygon.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_getUncleByBlockHashAndIndex",
7    "params": [
8        "0x0000000000000000000000000000000000000000000000000000000000000000",
9        "0x0"
10      ],
11    "id": 1
12  }'

Try it live in the Polygon playground.

Errors & troubleshooting

Common pitfalls

• An uncle header carries no transactions, so do not expect a transactions array in the response even on chains that do produce uncles.
• Polygon PoS produces no uncle blocks at all — its Bor/Heimdall consensus and L1 checkpoints mean every query here returns null, for both recent and historical blocks. Treat a null as normal, not an error.
• On Proof-of-Work history a block can reference at most two uncles, so index "0x2" and above always return null; on Polygon even index "0x0" returns null.

Supported networks

• Mainnet — Chain ID: 137
• Amoy — Chain ID: 80002

See also

• eth_getUncleByBlockNumberAndIndex
• eth_getUncleCountByBlockHash
• eth_getBlockByHash

1curl https://polygon.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"eth_getUncleByBlockHashAndIndex","params":["0x0000000000000000000000000000000000000000000000000000000000000000","0x0"]}'