> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chainstack.com/llms.txt
> Use this file to discover all available pages before exploring further.

# debug_traceBadBlock | Robinhood

> Robinhood Chain API method that traces all transactions in a block that has been marked as 'bad' by the node. Chainstack Robinhood Chain reference.

Robinhood Chain API method that traces all transactions in a block that has been marked as "bad" by the node. Bad blocks are blocks that failed validation during import. This method works similarly to `debug_traceBlockByHash` but looks up the block from the bad blocks cache instead of the canonical chain. It is primarily used for diagnosing why a block was rejected.

<Note>
  Learn how to [deploy a node](/docs/debug-and-trace-apis#robinhood) with the debug and trace API methods enabled.
</Note>

<Warning>
  This method is available for post-Nitro blocks only (block 22,207,815 and later). For pre-Nitro blocks, use the `arbtrace_*` methods instead.
</Warning>

## Parameters

* `hash` — the hash of the bad block to trace.
* `object` — (optional) an object identifying the type of tracer and its configuration:
  * `tracer` — the name of the tracer to use (`callTracer`, `prestateTracer`, `4byteTracer`, or a custom JS tracer).
  * `timeout` — the timeout for the tracing operation. Defaults to `5s`.
  * `reexec` — the number of blocks to re-execute to reconstruct historical state. Defaults to 128.

## Response

* `result` — an array of trace results, one per transaction in the block:
  * `txHash` — the hash of the transaction.
  * `result` — the trace output for the transaction (format depends on the tracer used).
  * `error` — an error message if the transaction trace failed.

## `debug_traceBadBlock` code examples

<CodeGroup>
  ```javascript ethers.js theme={"system"}
  const { JsonRpcProvider } = require("ethers");

  const provider = new JsonRpcProvider("CHAINSTACK_NODE_URL");

  async function call() {
    const result = await provider.send("debug_traceBadBlock", ["0xf4aab7a559489b816aca197b9a9315b5363a9932c52c3e8bfcf4152588ee096a"]);
    console.log(result);
  }

  call();
  ```

  ```python web3.py theme={"system"}
  from web3 import Web3

  node_url = "CHAINSTACK_NODE_URL"
  web3 = Web3(Web3.HTTPProvider(node_url))

  result = web3.provider.make_request("debug_traceBadBlock", ["0xf4aab7a559489b816aca197b9a9315b5363a9932c52c3e8bfcf4152588ee096a"])
  print(result)
  ```

  ```shell cURL theme={"system"}
  curl -X POST "CHAINSTACK_NODE_URL" \
    -H "Content-Type: application/json" \
    --data '{
      "jsonrpc": "2.0",
      "method": "debug_traceBadBlock",
      "params": ["0xf4aab7a559489b816aca197b9a9315b5363a9932c52c3e8bfcf4152588ee096a"],
      "id": 1
    }'
  ```
</CodeGroup>


## OpenAPI

````yaml openapi/robinhood_node_api/debug_and_trace/debug_traceBadBlock.json POST /
openapi: 3.0.0
info:
  title: Chainstack Node API
  version: 1.0.0
  description: This is an API for interacting with a Chainstack node.
servers:
  - url: >-
      https://robinhood-mainnet.core.chainstack.com/23cf4479b299ab4835d76c05c468ca6e
security: []
paths:
  /:
    post:
      tags:
        - upload
      summary: debug_traceBadBlock
      operationId: debug_traceBadBlock
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                id:
                  type: integer
                  default: 1
                jsonrpc:
                  type: string
                  default: '2.0'
                method:
                  type: string
                  default: debug_traceBadBlock
                params:
                  type: array
                  items:
                    anyOf:
                      - type: string
                        title: Block Hash
                        description: The hash of the bad block to trace.
                      - type: object
                        title: Tracing options
                  default:
                    - >-
                      0xf4aab7a559489b816aca197b9a9315b5363a9932c52c3e8bfcf4152588ee096a
      responses:
        '200':
          description: Returns trace results for each transaction in the bad block.
          content:
            application/json:
              schema:
                type: object
                properties:
                  jsonrpc:
                    type: string
                  id:
                    type: integer
                  result:
                    type: array
                    items:
                      type: object

````