debug_traceBlock

debug_traceBlock is the raw-bytes variant of block tracing on Ethereum mainnet (chain ID 1, native coin ETH). Instead of naming a block by hash or number, you hand the node the block itself as RLP-encoded bytes; it decodes them, re-runs every transaction against the parent state, and returns an opcode-level trace for each one in block order. This is the method to reach for when you already hold the serialized block — say, captured off the devp2p wire — rather than asking the node to look one up. Requests go to https://ethereum.therpc.io/YOUR_API_KEY. Like its siblings, it replays the whole block through the EVM, so a debug-enabled archive node is needed for the parent state of older blocks.

Use cases

• Trace a hand-built or modified block that has not been imported yet — useful in a simulation or fork-testing setup where you assemble candidate blocks and want to see how the EVM would execute them.
• Reproduce a block's execution straight from RLP bytes you already have, such as a frame captured from a devp2p session or pulled out of a client's database, without round-tripping through a hash lookup.

Parameters

Response

Example request

1curl https://ethereum.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 Ethereum playground.

Errors & troubleshooting

Common pitfalls

• Producing a valid RLP block is the hard part. Most workflows fetch the block via eth_getBlockByHash with full transactions, then re-encode header and body to RLP — get a single field wrong and the node throws -32602.
• The parent state still has to exist on the node. For a historical block that means archive state; without it you get block not found even though your RLP decodes fine.
• Performance matches debug_traceBlockByHash exactly — both replay every transaction in the block, so a busy mainnet block is just as heavy whichever entry point you use.

Supported networks

• Mainnet — Chain ID: 1
• Sepolia — Chain ID: 11155111

See also

• debug_traceBlockByNumber
• debug_traceBlockByHash
• debug_traceTransaction

1curl https://ethereum.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":["",{}]}'