eth_getUncleCountByBlockNumber

eth_getUncleCountByBlockNumber returns the number of uncle blocks referenced by the block at a given height or block tag (such as "latest" or "finalized"), as a hex string. Base — Coinbase's ETH-gas OP Stack rollup settling to Ethereum L1 — ships this method for full eth-namespace compatibility, but its single sequencer produces one canonical block roughly every 2 seconds with no competing forks, so the count is always 0x0. Query https://base.therpc.io/YOUR_API_KEY (Base mainnet, chain ID 8453 / 0x2105) at any height and the response will be 0x0.

Use cases

• Scan a sequential range of block heights for uncle presence to compute an uncle rate; on Base every height answers 0x0, so the computed rate is flat zero across the whole range.
• Run a quick count before fetching uncle details with eth_getUncleByBlockNumberAndIndex; since Base always reports 0x0, the detail call can be skipped entirely.

Parameters

Response

Example request

1curl https://base.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_getUncleCountByBlockNumber",
7    "params": ["latest"],
8    "id": 1
9  }'

Try it live in the Base playground.

Errors & troubleshooting

Common pitfalls

• On Base the result is always 0x0 regardless of which block or tag you query, because its OP Stack sequencer never produces uncles — do not build logic that expects a non-zero count here.
• The result is a hex string ("0x0"), not a number; parse it with parseInt(value, 16) or your library's hex helper before any numeric comparison.

Supported networks

• Mainnet — Chain ID: 8453
• Sepolia — Chain ID: 84532

See also

• eth_getUncleByBlockNumberAndIndex
• eth_getUncleCountByBlockHash
• eth_getBlockByNumber

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