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

#	Name	Type	Required	Description
1	`rlpBlock`	string	Yes	RLP-encoded block data. The block must be a valid, known block; the node re-executes it against the parent state.
2	`options`	object	No	Same tracer configuration object as debug_traceTransaction.

Response

Type	Description
array	Array of per-transaction trace results in block order, identical in shape to debug_traceBlockByHash output.

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

Code	Message	Cause
`-32601`	`Method not found`	debug namespace not enabled on the node.
`-32602`	`Invalid params`	RLP data is malformed, empty, or does not decode to a valid block structure.
`-32000`	`block not found`	Parent state for the provided block is not available (archive state missing).

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