debug_traceBlock

debug_traceBlock takes a block you supply as raw RLP-encoded bytes, re-executes it against its parent state on the Avalanche C-Chain, and returns an opcode-level trace for every transaction inside. The C-Chain is Avalanche's EVM chain, where AVAX pays for gas and Snowman consensus settles blocks in roughly one to two seconds. Unlike the by-hash and by-number variants, this method does not look the block up — you hand it the encoded block directly — so the node only needs the parent state to replay it. Send the call to https://avalanche.therpc.io/YOUR_API_KEY (chain ID 43114, hex 0xa86a) and you receive one trace result per transaction in block order.

Use cases

• Trace a custom or modified block that is not yet on the Avalanche C-Chain, for example inside a local simulation of a proposed transaction set.
• Reproduce a C-Chain block's execution when you already hold its RLP bytes, such as from a p2p capture or an exported block dump.

Parameters

Response

Example request

1curl https://avalanche.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 Avalanche playground.

Errors & troubleshooting

Common pitfalls

• Producing a correctly RLP-encoded C-Chain block is fiddly; you typically fetch it via eth_getBlockByHash with full transactions and re-encode it, and any encoding mistake yields an Invalid params error.
• The node needs the parent state to replay the block, so historical Avalanche blocks require an archive node.
• The performance profile matches debug_traceBlockByHash — it is a full block replay, so cost scales with how busy the block was, not with how the block was supplied.

Supported networks

• Mainnet — Chain ID: 43114
• Fuji

See also

• debug_traceBlockByNumber
• debug_traceBlockByHash
• debug_traceTransaction

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