testing_buildBlockV1

This method is a debugging and testing tool that simplifies the block production process into a single call.

**Specification:** - The client MUST build a new execution payload using the block specified by `parentBlockHash` as its parent. - The client MUST use the provided `payloadAttributes` to define the context of the new block. - If the `transactions` parameter is an empty array `[]`, the client MUST build an empty block (no transactions). - If the `transactions` parameter is JSON `null`, the client MAY build a block from its local transaction pool (mempool). - If the `transactions` parameter is a non-empty array, the client MUST include all transactions from the array on the block's transaction list, in the order they were provided, and MUST NOT include any transactions from its local transaction pool. - If `extraData` is provided, the client MUST set the `extraData` field of the resulting payload to this value. - This method MUST NOT modify the client's canonical chain or head block. It is a read-only method for payload generation.

**Security Considerations:** - This method is intended for testing environments ONLY and MUST NOT be exposed on public-facing RPC APIs. - It is strongly recommended that this method be disabled by default.

Builds a block on top of a given parentHash using the provided parameters. This is a testing-only method for generating test fixtures.

Parameters (by position)

Parent block hash string required

---

Payload attributes object required

PayloadAttributesV3

---

Show Payload attributes object

Payload attributes fields

• parentBeaconBlockRoot string

  32 byte hex value

  Match pattern: ^0x[0-9a-f]{64}$

  ---

• prevRandao string

  32 byte hex value

  Match pattern: ^0x[0-9a-f]{64}$

  ---

• suggestedFeeRecipient string

  hex encoded address

  Match pattern: ^0x[0-9a-fA-F]{40}$

  ---

• timestamp string

  hex encoded unsigned integer

  Match pattern: ^0x(0|[1-9a-f][0-9a-f]*)$

  ---

• withdrawals array<object>

  Validator withdrawal

  ---

  Show withdrawals object

  withdrawals fields

  • address string required

    recipient address for withdrawal value

    Match pattern: ^0x[0-9a-fA-F]{40}$

    ---

  • amount string required

    value contained in withdrawal

    Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,63})$

    ---

  • index string required

    index of withdrawal

    Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

    ---

  • validatorIndex string required

    index of validator that generated withdrawal

    Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

    ---

  • additionalProperties false

    ---

• additionalProperties true

  ---

Transactions array<string> or null required

An array of raw, signed transactions (hex-encoded) to include in the generated block, or null.

• If an empty array []: The client MUST build an empty block (no transactions).
• If null: The client MAY build a block from its local transaction pool (mempool).
• If a non-empty array: The client MUST include ALL transactions from this array in the resulting block, in the order provided, and MUST NOT include any transactions from its local mempool.

---

Show Option 1 Transactions array

Transactions fields

An array of raw, signed transactions (hex-encoded) to include in the generated block, or null.

• If an empty array []: The client MUST build an empty block (no transactions).
• If null: The client MAY build a block from its local transaction pool (mempool).
• If a non-empty array: The client MUST include ALL transactions from this array in the resulting block, in the order provided, and MUST NOT include any transactions from its local mempool.

Transactions array<string> required

An array of raw, signed transactions (hex-encoded) to include in the generated block, or null.

• If an empty array []: The client MUST build an empty block (no transactions).
• If null: The client MAY build a block from its local transaction pool (mempool).
• If a non-empty array: The client MUST include ALL transactions from this array in the resulting block, in the order provided, and MUST NOT include any transactions from its local mempool.

Match pattern: ^0x[0-9a-f]*$

---

Show Option 2 Transactions null

Transactions fields

An array of raw, signed transactions (hex-encoded) to include in the generated block, or null.

• If an empty array []: The client MUST build an empty block (no transactions).
• If null: The client MAY build a block from its local transaction pool (mempool).
• If a non-empty array: The client MUST include ALL transactions from this array in the resulting block, in the order provided, and MUST NOT include any transactions from its local mempool.

Transactions null required

An array of raw, signed transactions (hex-encoded) to include in the generated block, or null.

• If an empty array []: The client MUST build an empty block (no transactions).
• If null: The client MAY build a block from its local transaction pool (mempool).
• If a non-empty array: The client MUST include ALL transactions from this array in the resulting block, in the order provided, and MUST NOT include any transactions from its local mempool.

---

Extra data string or null

Data to be set as the extraData field of the built block. If provided, the client MUST use this exact value.

---

Show Option 1 hex encoded bytes string

hex encoded bytes fields

Data to be set as the extraData field of the built block. If provided, the client MUST use this exact value.

Extra data string

Data to be set as the extraData field of the built block. If provided, the client MUST use this exact value.

Match pattern: ^0x[0-9a-f]*$

---

Show Option 2 Extra data null

Extra data fields

Data to be set as the extraData field of the built block. If provided, the client MUST use this exact value.

Extra data null

Data to be set as the extraData field of the built block. If provided, the client MUST use this exact value.

---

Result

Response object object

Response object

---

Show Response object object

Response object fields

• blobsBundle object required

  Blobs bundle

  ---

  Show blobsBundle object

  blobsBundle fields

  • blobs array<string> required

    hex encoded bytes

    Match pattern: ^0x[0-9a-f]*$

    ---

  • commitments array<string> required

    48 hex encoded bytes

    Match pattern: ^0x[0-9a-f]{96}$

    ---

  • proofs array<string> required

    48 hex encoded bytes

    Match pattern: ^0x[0-9a-f]{96}$

    ---

  • additionalProperties true

    ---

• blockValue string required

  Expected block value

  Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,63})$

  ---

• executionPayload object required

  Execution payload

  ---

  Show executionPayload object

  executionPayload fields

  • baseFeePerGas string required

    Base fee per gas

    Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,63})$

    ---

  • blobGasUsed string required

    Blob gas used

    Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

    ---

  • blockHash string required

    Block hash

    Match pattern: ^0x[0-9a-f]{64}$

    ---

  • blockNumber string required

    Block number

    Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

    ---

  • excessBlobGas string required

    Excess blob gas

    Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

    ---

  • extraData string required

    Extra data

    Match pattern: ^0x[0-9a-f]{0,64}$

    ---

  • feeRecipient string required

    Recipient of transaction priority fees

    Match pattern: ^0x[0-9a-fA-F]{40}$

    ---

  • gasLimit string required

    Gas limit

    Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

    ---

  • gasUsed string required

    Gas used

    Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

    ---

  • logsBloom string required

    Bloom filter

    Match pattern: ^0x[0-9a-f]{512}$

    ---

  • parentHash string required

    Parent block hash

    Match pattern: ^0x[0-9a-f]{64}$

    ---

  • prevRandao string required

    Previous randao value

    Match pattern: ^0x[0-9a-f]{64}$

    ---

  • receiptsRoot string required

    Receipts root

    Match pattern: ^0x[0-9a-f]{64}$

    ---

  • stateRoot string required

    State root

    Match pattern: ^0x[0-9a-f]{64}$

    ---

  • timestamp string required

    Timestamp

    Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

    ---

  • transactions array<string> required

    hex encoded bytes

    Match pattern: ^0x[0-9a-f]*$

    ---

  • withdrawals array<object> required

    Withdrawal object V1

    ---

    Show withdrawals object

    withdrawals fields

    • address string required

      Withdrawal address

      Match pattern: ^0x[0-9a-fA-F]{40}$

      ---

    • amount string required

      Withdrawal amount

      Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

      ---

    • index string required

      Withdrawal index

      Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

      ---

    • validatorIndex string required

      Validator index

      Match pattern: ^0x(0|[1-9a-f][0-9a-f]{0,15})$

      ---

    • additionalProperties true

      ---

  • additionalProperties true

    ---

• executionRequests array<string>

  hex encoded bytes

  Match pattern: ^0x[0-9a-f]*$

  ---

• shouldOverrideBuilder boolean required

  Should override builder flag

  ---

• additionalProperties true

  ---

Errors

Error code: -32602

• code

  -32602

• message

  Invalid parameters

Error code: -32603

• code

  -32603

• message

  Internal error

Examples

testing_buildBlockV1 example

Request

{
  "params": [
    "0xe27a3e81bd7cfe2aec2cc9e832c73a17c93e7efcf659cf4b39883b96c48708c2",
    {
      "parentBeaconBlockRoot": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884365149a42212e8822",
      "prevRandao": "0x0000000000000000000000000000000000000000000000000000000000000000",
      "suggestedFeeRecipient": "0x0000000000000000000000000000000000000000",
      "timestamp": "0x1ce",
      "withdrawals": []
    },
    [],
    null
  ]
}

Response

{
  "blobsBundle": {
    "blobs": [],
    "commitments": [],
    "proofs": []
  },
  "blockValue": "0x0",
  "executionPayload": {
    "baseFeePerGas": "0x7",
    "blobGasUsed": "0x0",
    "blockHash": "0x1234567890123456789012345678901234567890123456789012345678901234",
    "blockNumber": "0x1",
    "excessBlobGas": "0x0",
    "extraData": "0x",
    "feeRecipient": "0x0000000000000000000000000000000000000000",
    "gasLimit": "0x1c9c380",
    "gasUsed": "0x0",
    "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
    "parentHash": "0xe27a3e81bd7cfe2aec2cc9e832c73a17c93e7efcf659cf4b39883b96c48708c2",
    "prevRandao": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "receiptsRoot": "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
    "stateRoot": "0xca3149fa9e37db08d1cd49c9061db1002ef1cd58db2210f2115c8c989b2bdf45",
    "timestamp": "0x1ce",
    "transactions": [],
    "withdrawals": []
  },
  "shouldOverrideBuilder": false
}

Request

Server URL:

{ "jsonrpc": "2.0", "method": "testing_buildBlockV1", "params": [ "0xe27a3e81bd7cfe2aec2cc9e832c73a17c93e7efcf659cf4b39883b96c48708c2", { "parentBeaconBlockRoot": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884365149a42212e8822", "prevRandao": "0x0000000000000000000000000000000000000000000000000000000000000000", "suggestedFeeRecipient": "0x0000000000000000000000000000000000000000", "timestamp": "0x1ce", "withdrawals": [] }, [], null ], "id": 1 }