debug_traceBlock

debug_traceBlock takes a full block as RLP-encoded bytes, re-executes every transaction in it against the parent state, and returns an opcode-level trace for each. Unlike the by-hash and by-number variants, you hand the OP Mainnet node the raw block itself rather than pointing at one already in its database — useful when you hold the encoded bytes but not a canonical reference. OP Mainnet is the OP Stack rollup that settles to Ethereum L1 and meters gas in ETH; send the request to https://optimism.therpc.io/YOUR_API_KEY (chain ID 10, 0xa) with the 0x-prefixed RLP block and an optional tracer config.

Use cases

• Trace a custom or modified block that is not yet on the OP Mainnet canonical chain — for example one built in a local simulation environment.
• Reproduce a block's execution when you already hold its RLP bytes, such as bytes captured from the Superchain p2p layer.

Parameters

Response

Example request

1curl https://optimism.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "debug_traceBlock",
7    "params": [
8        "0xf9...",
9        {}
10      ],
11    "id": 1
12  }'

Try it live in the Optimism playground.

Errors & troubleshooting

Common pitfalls

• Producing a correctly RLP-encoded OP Mainnet block is fiddly; most callers fetch it via eth_getBlockByHash with full transactions and re-encode, which is error-prone.
• The node needs the parent state to replay against, so historical blocks require an archive OP Mainnet node.
• Performance matches debug_traceBlockByHash — it is a full block replay, so a dense block is just as heavy here.

Supported networks

• Mainnet — Chain ID: 10
• Sepolia — Chain ID: 11155420

See also

• debug_traceBlockByNumber
• debug_traceBlockByHash
• debug_traceTransaction

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