eth_getUncleCountByBlockHash

eth_getUncleCountByBlockHash returns the number of uncle blocks referenced by the block identified by a given hash, as a hex string. On Polygon — the MATIC-powered PoS chain reachable at https://polygon.therpc.io/YOUR_API_KEY (chain ID 137, 0x89) — that count is always "0x0", because the Bor/Heimdall Proof-of-Stake consensus and its L1 checkpoints never produce uncles. The method is retained for Ethereum JSON-RPC compatibility so that wallets, indexers, and libraries expecting the full standard interface continue to function against Polygon.

Use cases

• Cheaply check whether a block references any uncles before spending calls on eth_getUncleByBlockHashAndIndex; on Polygon the count is always "0x0", so that follow-up is never needed.
• Build a historical uncle-rate time series for network-health research. This is meaningful on Proof-of-Work chains; on Polygon PoS the series is flat at zero, which itself documents the absence of forks under its checkpointed consensus.

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_getUncleCountByBlockHash",
7    "params": ["0x0000000000000000000000000000000000000000000000000000000000000000"],
8    "id": 1
9  }'

Try it live in the Polygon playground.

Errors & troubleshooting

Common pitfalls

• On Polygon PoS every block returns "0x0"; the method only carries non-zero values on historical Proof-of-Work data from other chains, so do not build Polygon logic that expects a positive count.
• An unknown or non-existent block hash returns null rather than "0x0" — distinguish "block not found" (null) from "block has zero uncles" ("0x0") when handling the response.

Supported networks

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

See also

• eth_getUncleByBlockHashAndIndex
• eth_getUncleCountByBlockNumber
• 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_getUncleCountByBlockHash","params":["0x0000000000000000000000000000000000000000000000000000000000000000"]}'