go-ethereum/docs/interacting-with-geth/rpc/ns-debug.md

---
title: debug Namespace
description: methods in the debug namespace
---

The `debug` API gives you access to several non-standard RPC methods, which will allow you to inspect, debug and set certain debugging flags during runtime.

### debug_accountRange

Enumerates all accounts at a given block with paging capability. `maxResults` are returned in the page and the items have keys that come after the `start` key (hashed address).

If `incompletes` is false, then accounts for which the key preimage (i.e: the `address`) doesn't exist in db are skipped. NB: geth by default does not store preimages.

| Client  | Method invocation                                                                                                |
| :------ | ---------------------------------------------------------------------------------------------------------------- |
| Console | `debug.accountRange(blockNrOrHash, start, maxResults, nocode, nostorage, incompletes)`                           |
| RPC     | `{"method": "debug_getHeaderRlp", "params": [blockNrOrHash, start, maxResults, nocode, nostorage, incompletes]}` |

### debug_backtraceAt

Sets the logging backtrace location. When a backtrace location is set and a log message is emitted at that location, the stack of the goroutine executing the log statement will be printed to stderr.

The location is specified as `<filename>:<line>`.

| Client  | Method invocation                                     |
| :------ | ----------------------------------------------------- |
| Console | `debug.backtraceAt(string)`                           |
| RPC     | `{"method": "debug_backtraceAt", "params": [string]}` |

Example:

```js
> debug.backtraceAt("server.go:443")
```

### debug_blockProfile

Turns on block profiling for the given duration and writes profile data to disk. It uses a profile rate of 1 for most accurate information. If a different rate is desired, set the rate and write the profile manually using `debug_writeBlockProfile`.

| Client  | Method invocation                                              |
| :------ | -------------------------------------------------------------- |
| Console | `debug.blockProfile(file, seconds)`                            |
| RPC     | `{"method": "debug_blockProfile", "params": [string, number]}` |

### debug_chaindbCompact

Flattens the entire key-value database into a single level, removing all unused slots and merging all keys.

| Client  | Method invocation                                  |
| :------ | -------------------------------------------------- |
| Console | `debug.chaindbCompact()`                           |
| RPC     | `{"method": "debug_chaindbCompact", "params": []}` |

### debug_chaindbProperty

Returns leveldb properties of the key-value database.

| Client  | Method invocation                                           |
| :------ | ----------------------------------------------------------- |
| Console | `debug.chaindbProperty(property string)`                    |
| RPC     | `{"method": "debug_chaindbProperty", "params": [property]}` |

### debug_cpuProfile

Turns on CPU profiling for the given duration and writes profile data to disk.

| Client  | Method invocation                                            |
| :------ | ------------------------------------------------------------ |
| Console | `debug.cpuProfile(file, seconds)`                            |
| RPC     | `{"method": "debug_cpuProfile", "params": [string, number]}` |

### debug_dbAncient

Retrieves an ancient binary blob from the freezer. The freezer is a collection of append-only immutable files. The first argument `kind` specifies which table to look up data from. The list of all table kinds are as follows:

- `headers`: block headers
- `hashes`: canonical hash table (block number -> block hash)
- `bodies`: block bodies
- `receipts`: block receipts
- `diffs`: total difficulty table (block number -> td)

| Client  | Method invocation                                           |
| :------ | ----------------------------------------------------------- |
| Console | `debug.dbAncient(kind string, number uint64)`               |
| RPC     | `{"method": "debug_dbAncient", "params": [string, number]}` |

### debug_dbAncients

Returns the number of ancient items in the ancient store.

| Client  | Method invocation                |
| :------ | -------------------------------- |
| Console | `debug.dbAncients()`             |
| RPC     | `{"method": "debug_dbAncients"}` |

### debug_dbGet

Returns the raw value of a key stored in the database.

| Client  | Method invocation                            |
| :------ | -------------------------------------------- |
| Console | `debug.dbGet(key string)`                    |
| RPC     | `{"method": "debug_dbGet", "params": [key]}` |

### debug_dumpBlock

Retrieves the state that corresponds to the block number and returns a list of accounts (including storage and code).

| Client  | Method invocation                                     |
| :------ | ----------------------------------------------------- |
| Go      | `debug.DumpBlock(number uint64) (state.World, error)` |
| Console | `debug.traceBlockByHash(number, [options])`           |
| RPC     | `{"method": "debug_dumpBlock", "params": [number]}`   |

#### Example

```js
> debug.dumpBlock(10)
{
    fff7ac99c8e4feb60c9750054bdc14ce1857f181: {
      balance: "49358640978154672",
      code: "",
      codeHash: "c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470",
      nonce: 2,
      root: "56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
      storage: {}
    },
    fffbca3a38c3c5fcb3adbb8e63c04c3e629aafce: {
      balance: "3460945928",
      code: "",
      codeHash: "c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470",
      nonce: 657,
      root: "56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
      storage: {}
    }
  },
  root: "19f4ed94e188dd9c7eb04226bd240fa6b449401a6c656d6d2816a87ccaf206f1"
}
```

### debug_freeOSMemory

Forces garbage collection

| Client  | Method invocation                                |
| :------ | ------------------------------------------------ |
| Go      | `debug.FreeOSMemory()`                           |
| Console | `debug.freeOSMemory()`                           |
| RPC     | `{"method": "debug_freeOSMemory", "params": []}` |

### debug_freezeClient

Forces a temporary client freeze, normally when the server is overloaded. Available as part of LES light server.

| Client  | Method invocation                                    |
| :------ | ---------------------------------------------------- |
| Console | `debug.freezeClient(node string)`                    |
| RPC     | `{"method": "debug_freezeClient", "params": [node]}` |

### debug_gcStats

Returns garbage collection statistics.

See https://golang.org/pkg/runtime/debug/#GCStats for information about the fields of the returned object.

| Client  | Method invocation                           |
| :------ | ------------------------------------------- |
| Console | `debug.gcStats()`                           |
| RPC     | `{"method": "debug_gcStats", "params": []}` |

### debug_getAccessibleState

Returns the first number where the node has accessible state on disk. This is the post-state of that block and the pre-state of the next
block. The (from, to) parameters are the sequence of blocks to search, which can go either forwards or backwards.

Note: to get the last state pass in the range of blocks in reverse, i.e. (last, first).

| Client  | Method invocation                                              |
| :------ | -------------------------------------------------------------- |
| Console | `debug.getAccessibleState(from, to rpc.BlockNumber)`           |
| RPC     | `{"method": "debug_getAccessibleState", "params": [from, to]}` |

### debug_getBadBlocks

Returns a list of the last 'bad blocks' that the client has seen on the network and returns them as a JSON list of block-hashes.

| Client  | Method invocation                                |
| :------ | ------------------------------------------------ |
| Console | `debug.getBadBlocks()`                           |
| RPC     | `{"method": "debug_getBadBlocks", "params": []}` |

### debug_getBlockRlp

Retrieves and returns the RLP encoded block by number.

| Client  | Method invocation                                     |
| :------ | ----------------------------------------------------- |
| Go      | `debug.GetBlockRlp(number uint64) (string, error)`    |
| Console | `debug.getBlockRlp(number, [options])`                |
| RPC     | `{"method": "debug_getBlockRlp", "params": [number]}` |

References: [RLP](https://ethereum.org/en/developers/docs/data-structures-and-encoding/rlp/)

### debug_getHeaderRlp

Returns an RLP-encoded header.

| Client  | Method invocation                                   |
| :------ | --------------------------------------------------- |
| Console | `debug.getHeaderRlp(blockNum)`                      |
| RPC     | `{"method": "debug_getHeaderRlp", "params": [num]}` |

### debug_getModifiedAccountsByHash

Returns all accounts that have changed between the two blocks specified. A change is defined as a difference in nonce, balance, code hash, or storage hash. With one parameter, returns the list of accounts modified in the specified block.

| Client  | Method invocation                                                               |
| :------ | ------------------------------------------------------------------------------- |
| Console | `debug.getModifiedAccountsByHash(startHash, endHash)`                           |
| RPC     | `{"method": "debug_getModifiedAccountsByHash", "params": [startHash, endHash]}` |

### debug_getModifiedAccountsByNumber

Returns all accounts that have changed between the two blocks specified. A change is defined as a difference in nonce, balance, code hash or
storage hash.

| Client  | Method invocation                                                               |
| :------ | ------------------------------------------------------------------------------- |
| Console | `debug.getModifiedAccountsByNumber(startNum uint64, endNum uint64)`             |
| RPC     | `{"method": "debug_getModifiedAccountsByNumber", "params": [startNum, endNum]}` |

<Note> Geth only keeps recent trie nodes and preimages of keys in memory - for older blocks this information is deleted by Geth's garbage collection. This means that calls to `debug_GetModifiedAccountsByNumber` on blocks that are old enough to be eligible for garbage collection will return an error due to the trie nodes and preimages being unavailable. To fix this, run Geth with `--cache.preimages=true` to prevent the relevant data being lost to the garbage collector </Note>

### debug_getRawReceipts

Returns the consensus-encoding of all receipts in a single block.

| Client  | Method invocation                                               |
| :------ | --------------------------------------------------------------- |
| Console | `debug.getRawReceipts(blockNrOrHash)`                           |
| RPC     | `{"method": "debug_getRawReceipts", "params": [blockNrOrHash]}` |

### debug_goTrace

Turns on Go runtime tracing for the given duration and writes trace data to disk.

| Client  | Method invocation                                         |
| :------ | --------------------------------------------------------- |
| Console | `debug.goTrace(file, seconds)`                            |
| RPC     | `{"method": "debug_goTrace", "params": [string, number]}` |

### debug_intermediateRoots

Executes a block (bad- or canon- or side-), and returns a list of intermediate roots: the stateroot after each transaction.

| Client  | Method invocation                                                  |
| :------ | ------------------------------------------------------------------ |
| Console | `debug.intermediateRoots(blockHash, [options])`                    |
| RPC     | `{"method": "debug_intermediateRoots", "params": [blockHash, {}]}` |

### debug_memStats

Returns detailed runtime memory statistics.

See https://golang.org/pkg/runtime/#MemStats for information about the fields of the returned object.

| Client  | Method invocation                            |
| :------ | -------------------------------------------- |
| Console | `debug.memStats()`                           |
| RPC     | `{"method": "debug_memStats", "params": []}` |

### debug_mutexProfile

Turns on mutex profiling for nsec seconds and writes profile data to file. It uses a profile rate of 1 for most accurate information. If a different rate is desired, set the rate and write the profile manually.

| Client  | Method invocation                                          |
| :------ | ---------------------------------------------------------- |
| Console | `debug.mutexProfile(file, nsec)`                           |
| RPC     | `{"method": "debug_mutexProfile", "params": [file, nsec]}` |

### debug_preimage

Returns the preimage for a sha3 hash, if known.

| Client  | Method invocation                                |
| :------ | ------------------------------------------------ |
| Console | `debug.preimage(hash)`                           |
| RPC     | `{"method": "debug_preimage", "params": [hash]}` |

### debug_printBlock

Retrieves a block and returns its pretty printed form.

| Client  | Method invocation                                    |
| :------ | ---------------------------------------------------- |
| Console | `debug.printBlock(number uint64)`                    |
| RPC     | `{"method": "debug_printBlock", "params": [number]}` |

### debug_seedHash

Fetches and retrieves the seed hash of the block by number

| Client  | Method invocation                                  |
| :------ | -------------------------------------------------- |
| Go      | `debug.SeedHash(number uint64) (string, error)`    |
| Console | `debug.seedHash(number, [options])`                |
| RPC     | `{"method": "debug_seedHash", "params": [number]}` |

### debug_setBlockProfileRate

Sets the rate (in samples/sec) of goroutine block profile data collection. A non-zero rate enables block profiling, setting it to zero stops the profile. Collected profile data can be written using `debug_writeBlockProfile`.

| Client  | Method invocation                                             |
| :------ | ------------------------------------------------------------- |
| Console | `debug.setBlockProfileRate(rate)`                             |
| RPC     | `{"method": "debug_setBlockProfileRate", "params": [number]}` |

### debug_setGCPercent

Sets the garbage collection target percentage. A negative value disables garbage collection.

| Client  | Method invocation                                 |
| :------ | ------------------------------------------------- |
| Go      | `debug.SetGCPercent(v int)`                       |
| Console | `debug.setGCPercent(v)`                           |
| RPC     | `{"method": "debug_setGCPercent", "params": [v]}` |

### debug_setHead

Sets the current head of the local chain by block number. **Note**, this is a destructive action and may severely damage your chain. Use with _extreme_ caution.

| Client  | Method invocation                                 |
| :------ | ------------------------------------------------- |
| Go      | `debug.SetHead(number uint64)`                    |
| Console | `debug.setHead(number)`                           |
| RPC     | `{"method": "debug_setHead", "params": [number]}` |

References:
[Ethash](https://ethereum.org/en/developers/docs/consensus-mechanisms/pow/mining-algorithms/ethash/)

### debug_setMutexProfileFraction

Sets the rate of mutex profiling.

| Client  | Method invocation                                               |
| :------ | --------------------------------------------------------------- |
| Console | `debug.setMutexProfileFraction(rate int)`                       |
| RPC     | `{"method": "debug_setMutexProfileFraction", "params": [rate]}` |

### debug_stacks

Returns a printed representation of the stacks of all goroutines. Note that the web3 wrapper for this method takes care of the printing and does not return the string.

| Client  | Method invocation                          |
| :------ | ------------------------------------------ |
| Console | `debug.stacks()`                           |
| RPC     | `{"method": "debug_stacks", "params": []}` |

### debug_standardTraceBlockToFile

When JS-based tracing (see below) was first implemented, the intended usecase was to enable long-running tracers that could stream results back via a subscription channel. This method works a bit differently. (For full details, see [PR](https://github.com/ethereum/go-ethereum/pull/17914))

- It streams output to disk during the execution, to not blow up the memory usage on the node
- It uses `jsonl` as output format (to allow streaming)
- Uses a cross-client standardized output, so called 'standard json'
  - Uses `op` for string-representation of opcode, instead of `op`/`opName` for numeric/string, and other simlar small differences.
  - has `refund`
  - Represents memory as a contiguous chunk of data, as opposed to a list of `32`-byte segments like `debug_traceTransaction`

This means that this method is only 'useful' for callers who control the node -- at least sufficiently to be able to read the artefacts from the filesystem after the fact.

The method can be used to dump a certain transaction out of a given block:

```js
> debug.standardTraceBlockToFile("0x0bbe9f1484668a2bf159c63f0cf556ed8c8282f99e3ffdb03ad2175a863bca63", {txHash:"0x4049f61ffbb0747bb88dc1c85dd6686ebf225a3c10c282c45a8e0c644739f7e9", disableMemory:true})
["/tmp/block_0x0bbe9f14-14-0x4049f61f-099048234"]
```

Or all txs from a block:

```js
> debug.standardTraceBlockToFile("0x0bbe9f1484668a2bf159c63f0cf556ed8c8282f99e3ffdb03ad2175a863bca63", {disableMemory:true})
["/tmp/block_0x0bbe9f14-0-0xb4502ea7-409046657", "/tmp/block_0x0bbe9f14-1-0xe839be8f-954614764", "/tmp/block_0x0bbe9f14-2-0xc6e2052f-542255195", "/tmp/block_0x0bbe9f14-3-0x01b7f3fe-209673214", "/tmp/block_0x0bbe9f14-4-0x0f290422-320999749", "/tmp/block_0x0bbe9f14-5-0x2dc0fb80-844117472", "/tmp/block_0x0bbe9f14-6-0x35542da1-256306111", "/tmp/block_0x0bbe9f14-7-0x3e199a08-086370834", "/tmp/block_0x0bbe9f14-8-0x87778b88-194603593", "/tmp/block_0x0bbe9f14-9-0xbcb081ba-629580052", "/tmp/block_0x0bbe9f14-10-0xc254381a-578605923", "/tmp/block_0x0bbe9f14-11-0xcc434d58-405931366", "/tmp/block_0x0bbe9f14-12-0xce61967d-874423181", "/tmp/block_0x0bbe9f14-13-0x05a20b35-267153288", "/tmp/block_0x0bbe9f14-14-0x4049f61f-606653767", "/tmp/block_0x0bbe9f14-15-0x46d473d2-614457338", "/tmp/block_0x0bbe9f14-16-0x35cf5500-411906321", "/tmp/block_0x0bbe9f14-17-0x79222961-278569788", "/tmp/block_0x0bbe9f14-18-0xad84e7b1-095032683", "/tmp/block_0x0bbe9f14-19-0x4bd48260-019097038", "/tmp/block_0x0bbe9f14-20-0x1517411d-292624085", "/tmp/block_0x0bbe9f14-21-0x6857e350-971385904", "/tmp/block_0x0bbe9f14-22-0xbe3ae2ca-236639695"]

```

Files are created in a temp-location, with the naming standard `block_<blockhash:4>-<txindex>-<txhash:4>-<random suffix>`. Each opcode immediately streams to file, with no in-geth buffering aside from whatever buffering the os normally does.

On the server side, it also adds some more info when regenerating historical state, namely, the reexec-number if `required historical state is not avaiable` is encountered, so a user can experiment with increasing that setting. It also prints out the remaining block until it reaches target:

```terminal
INFO [10-15|13:48:25.263] Regenerating historical state            block=2385959 target=2386012 remaining=53   elapsed=3m30.990537767s
INFO [10-15|13:48:33.342] Regenerating historical state            block=2386012 target=2386012 remaining=0    elapsed=3m39.070073163s
INFO [10-15|13:48:33.343] Historical state regenerated             block=2386012 elapsed=3m39.070454362s nodes=10.03mB preimages=652.08kB
INFO [10-15|13:48:33.352] Wrote trace                              file=/tmp/block_0x14490c57-0-0xfbbd6d91-715824834
INFO [10-15|13:48:33.352] Wrote trace                              file=/tmp/block_0x14490c57-1-0x71076194-187462969
INFO [10-15|13:48:34.421] Wrote trace file=/tmp/block_0x14490c57-2-0x3f4263fe-056924484
```

The `options` is as follows:

```js
type StdTraceConfig struct {
  *vm.LogConfig
  Reexec *uint64
  TxHash *common.Hash
}
```

### debug_standardTraceBadBlockToFile

This method is similar to `debug_standardTraceBlockToFile`, but can be used to obtain info about a block which has been _rejected_ as invalid (for some reason).

### debug_startCPUProfile

Turns on CPU profiling indefinitely, writing to the given file.

| Client  | Method invocation                                         |
| :------ | --------------------------------------------------------- |
| Console | `debug.startCPUProfile(file)`                             |
| RPC     | `{"method": "debug_startCPUProfile", "params": [string]}` |

### debug_startGoTrace

Starts writing a Go runtime trace to the given file.

| Client  | Method invocation                                      |
| :------ | ------------------------------------------------------ |
| Console | `debug.startGoTrace(file)`                             |
| RPC     | `{"method": "debug_startGoTrace", "params": [string]}` |

### debug_stopCPUProfile

Stops an ongoing CPU profile.

| Client  | Method invocation                                  |
| :------ | -------------------------------------------------- |
| Console | `debug.stopCPUProfile()`                           |
| RPC     | `{"method": "debug_stopCPUProfile", "params": []}` |

### debug_stopGoTrace

Stops writing the Go runtime trace.

| Client  | Method invocation                               |
| :------ | ----------------------------------------------- |
| Console | `debug.startGoTrace(file)`                      |
| RPC     | `{"method": "debug_stopGoTrace", "params": []}` |

### debug_storageRangeAt

Returns the storage at the given block height and transaction index. The result can be paged by providing a `maxResult` to cap the number of storage slots returned as well as specifying the offset via `keyStart` (hash of storage key).

| Client  | Method invocation                                                                                        |
| :------ | -------------------------------------------------------------------------------------------------------- |
| Console | `debug.storageRangeAt(blockHash, txIdx, contractAddress, keyStart, maxResult)`                           |
| RPC     | `{"method": "debug_storageRangeAt", "params": [blockHash, txIdx, contractAddress, keyStart, maxResult]}` |

### debug_traceBadBlock

Returns the structured logs created during the execution of EVM against a block pulled from the pool of bad ones and returns them as a JSON object.
For the second parameter see [TraceConfig](#traceconfig) reference.

| Client  | Method invocation                                              |
| :------ | -------------------------------------------------------------- |
| Console | `debug.traceBadBlock(blockHash, [options])`                    |
| RPC     | `{"method": "debug_traceBadBlock", "params": [blockHash, {}]}` |

### debug_traceBlock

The `traceBlock` method will return a full stack trace of all invoked opcodes of all transaction that were included in this block. **Note**, the parent of this block must be present or it will fail. For the second parameter see [TraceConfig](#traceconfig) reference.

| Client  | Method invocation                                                         |
| :------ | ------------------------------------------------------------------------- |
| Go      | `debug.TraceBlock(blockRlp []byte, config *TraceConfig) BlockTraceResult` |
| Console | `debug.traceBlock(tblockRlp, [options])`                                  |
| RPC     | `{"method": "debug_traceBlock", "params": [blockRlp, {}]}`                |

References:
[RLP](https://ethereum.org/en/developers/docs/data-structures-and-encoding/rlp/)

#### Example

```js
> debug.traceBlock("0xblock_rlp")
{
  gas: 85301,
  returnValue: "",
  structLogs: [{
      depth: 1,
      error: "",
      gas: 162106,
      gasCost: 3,
      memory: null,
      op: "PUSH1",
      pc: 0,
      stack: [],
      storage: {}
  },
    /* snip */
  {
      depth: 1,
      error: "",
      gas: 100000,
      gasCost: 0,
      memory: ["0000000000000000000000000000000000000000000000000000000000000006", "0000000000000000000000000000000000000000000000000000000000000000", "0000000000000000000000000000000000000000000000000000000000000060"],
      op: "STOP",
      pc: 120,
      stack: ["00000000000000000000000000000000000000000000000000000000d67cbec9"],
      storage: {
        0000000000000000000000000000000000000000000000000000000000000004: "8241fa522772837f0d05511f20caa6da1d5a3209000000000000000400000001",
        0000000000000000000000000000000000000000000000000000000000000006: "0000000000000000000000000000000000000000000000000000000000000001",
        f652222313e28459528d920b65115c16c04f3efc82aaedc97be59f3f377c0d3f: "00000000000000000000000002e816afc1b5c0f39852131959d946eb3b07b5ad"
      }
  }]
```

### debug_traceBlockByNumber

Similar to [debug_traceBlock](#debug_traceblock), `traceBlockByNumber` accepts a block number and will replay the block that is already present in the database. For the second parameter see [TraceConfig](#traceconfig) reference.

| Client  | Method invocation                                                               |
| :------ | ------------------------------------------------------------------------------- |
| Go      | `debug.TraceBlockByNumber(number uint64, config *TraceConfig) BlockTraceResult` |
| Console | `debug.traceBlockByNumber(number, [options])`                                   |
| RPC     | `{"method": "debug_traceBlockByNumber", "params": [number, {}]}`                |

References:
[RLP](https://ethereum.org/en/developers/docs/data-structures-and-encoding/rlp/)

### debug_traceBlockByHash

Similar to [debug_traceBlock](#debug_traceblock), `traceBlockByHash` accepts a block hash and will replay the block that is already present in the database. For the second parameter see [TraceConfig](#traceconfig) reference.

| Client  | Method invocation                                                                |
| :------ | -------------------------------------------------------------------------------- |
| Go      | `debug.TraceBlockByHash(hash common.Hash, config *TraceConfig) BlockTraceResult` |
| Console | `debug.traceBlockByHash(hash, [options])`                                        |
| RPC     | `{"method": "debug_traceBlockByHash", "params": [hash {}]}`                      |

References:
[RLP](https://ethereum.org/en/developers/docs/data-structures-and-encoding/rlp/)

### debug_traceBlockFromFile

Similar to [debug_traceBlock](#debug_traceblock), `traceBlockFromFile` accepts a file containing the RLP of the block. For the second parameter see [TraceConfig](#traceconfig) reference.

| Client  | Method invocation                                                                 |
| :------ | --------------------------------------------------------------------------------- |
| Go      | `debug.TraceBlockFromFile(fileName string, config *TraceConfig) BlockTraceResult` |
| Console | `debug.traceBlockFromFile(fileName, [options])`                                   |
| RPC     | `{"method": "debug_traceBlockFromFile", "params": [fileName, {}]}`                |

References:
[RLP](https://ethereum.org/en/developers/docs/data-structures-and-encoding/rlp/)

### debug_traceCall

The `debug_traceCall` method lets you run an `eth_call` within the context of the given block execution using the final state of parent block as the base. The first argument (just as in `eth_call`) is a [transaction object](/docs/interacting-with-geth/rpc/objects#transaction-call-object). The block can be specified either by hash or by number as the second argument. The trace can be configured similar to `debug_traceTransaction`, see [TraceConfig](#traceconfig). The method returns the same output as `debug_traceTransaction`.

| Client  | Method invocation                                                                                                           |
| :-----: | --------------------------------------------------------------------------------------------------------------------------- |
|   Go    | `debug.TraceCall(args ethapi.CallArgs, blockNrOrHash rpc.BlockNumberOrHash, config *TraceConfig) (*ExecutionResult, error)` |
| Console | `debug.traceCall(object, blockNrOrHash, [options])`                                                                         |
|   RPC   | `{"method": "debug_traceCall", "params": [object, blockNrOrHash, {}]}`                                                      |

#### Example

No specific call options:

```js
> debug.traceCall(null, "0x0")
{
  failed: false,
  gas: 53000,
  returnValue: "",
  structLogs: []
}
```

Tracing a call with a destination and specific sender, disabling the storage and memory output (less data returned over RPC)

```js
debug.traceCall(
  {
    from: '0xdeadbeef29292929192939494959594933929292',
    to: '0xde929f939d939d393f939393f93939f393929023',
    gas: '0x7a120',
    data: '0xf00d4b5d00000000000000000000000001291230982139282304923482304912923823920000000000000000000000001293123098123928310239129839291010293810'
  },
  'latest',
  { disableStorage: true, disableMemory: true }
);
```

It is possible to supply 'overrides' for both state-data (accounts/storage) and block data (number, timestamp etc). In the example below, a call which executes `NUMBER` is performed, and the overridden number is placed on the stack:

```js
> debug.traceCall({
	from: eth.accounts[0],
	value:"0x1",
	gasPrice: "0xffffffff",
	gas: "0xffff",
	input: "0x43"},
	"latest",
	{"blockoverrides":
		{"number": "0x50"}
	})
{
  failed: false,
  gas: 53018,
  returnValue: "",
  structLogs: [{
      depth: 1,
      gas: 12519,
      gasCost: 2,
      op: "NUMBER",
      pc: 0,
      stack: []
  }, {
      depth: 1,
      gas: 12517,
      gasCost: 0,
      op: "STOP",
      pc: 1,
      stack: ["0x50"]
  }]
}
```

Curl example:

```sh
> curl -H "Content-Type: application/json" -X POST  localhost:8545 --data '{"jsonrpc":"2.0","method":"debug_traceCall","params":[null, "pending"],"id":1}'
{"jsonrpc":"2.0","id":1,"result":{"gas":53000,"failed":false,"returnValue":"","structLogs":[]}}
```

### debug_traceChain

Returns the structured logs created during the execution of EVM between two blocks (excluding start) as a JSON object. This endpoint must be invoked via `debug_subscribe` as follows:

```js
const res = provider.send('debug_subscribe', ['traceChain', '0x3f3a2a', '0x3f3a2b'])`
```

please refer to the [subscription page](/docs/interacting-with-geth/rpc/pubsub) for more details.

### debug_traceTransaction

**OBS** In most scenarios, `debug.standardTraceBlockToFile` is better suited for tracing!

The `traceTransaction` debugging method will attempt to run the transaction in the exact same manner as it was executed on the network. It will replay any transaction that may have been executed prior to this one before it will finally attempt to execute the transaction that corresponds to the given
hash.

| Client  | Method invocation                                                                           |
| :------ | ------------------------------------------------------------------------------------------- |
| Go      | `debug.TraceTransaction(txHash common.Hash, config *TraceConfig) (*ExecutionResult, error)` |
| Console | `debug.traceTransaction(txHash, [options])`                                                 |
| RPC     | `{"method": "debug_traceTransaction", "params": [txHash, {}]}`                              |

#### TraceConfig

In addition to the hash of the transaction you may give it a secondary _optional_ argument, which specifies the options for this specific call. The possible options are:

- `disableStorage`: `BOOL`. Setting this to true will disable storage capture (default = false).
- `disableStack`: `BOOL`. Setting this to true will disable stack capture (default = false).
- `enableMemory`: `BOOL`. Setting this to true will enable memory capture (default = false).
- `enableReturnData`: `BOOL`. Setting this to true will enable return data capture (default = false).
- `tracer`: `STRING`. Name for built-in tracer or Javascript expression. See below for more details.

If set, the previous four arguments will be ignored.

- `timeout`: `STRING`. Overrides the default timeout of 5 seconds for JavaScript-based tracing calls.
  Valid values are described [here](https://golang.org/pkg/time/#ParseDuration).
- `tracerConfig`: Config for the specified `tracer`. For example see callTracer's [config](/docs/developers/evm-tracing/built-in-tracers#config).

Geth comes with a bundle of [built-in tracers](/docs/developers/evm-tracing/built-in-tracers), each providing various data about a transaction. This method defaults to the [struct logger](/docs/developers/evm-tracing/built-in-tracers#structopcode-logger). The `tracer` field of the second parameter can be set to use any of the other tracers. Alternatively a [custom tracer](/docs/developers/evm-tracing/custom-tracer) can be implemented in either Go or Javascript.

#### Example

```js
> debug.traceTransaction("0x2059dd53ecac9827faad14d364f9e04b1d5fe5b506e3acc886eff7a6f88a696a")
{
  gas: 85301,
  returnValue: "",
  structLogs: [{
      depth: 1,
      error: "",
      gas: 162106,
      gasCost: 3,
      memory: null,
      op: "PUSH1",
      pc: 0,
      stack: [],
      storage: {}
  },
    /* snip */
  {
      depth: 1,
      error: "",
      gas: 100000,
      gasCost: 0,
      memory: ["0000000000000000000000000000000000000000000000000000000000000006", "0000000000000000000000000000000000000000000000000000000000000000", "0000000000000000000000000000000000000000000000000000000000000060"],
      op: "STOP",
      pc: 120,
      stack: ["00000000000000000000000000000000000000000000000000000000d67cbec9"],
      storage: {
        0000000000000000000000000000000000000000000000000000000000000004: "8241fa522772837f0d05511f20caa6da1d5a3209000000000000000400000001",
        0000000000000000000000000000000000000000000000000000000000000006: "0000000000000000000000000000000000000000000000000000000000000001",
        f652222313e28459528d920b65115c16c04f3efc82aaedc97be59f3f377c0d3f: "00000000000000000000000002e816afc1b5c0f39852131959d946eb3b07b5ad"
      }
  }]
```

### debug_verbosity

Sets the logging verbosity ceiling. Log messages with level up to and including the given level will be printed.

The verbosity of individual packages and source files can be raised using `debug_vmodule`.

| Client  | Method invocation                                 |
| :------ | ------------------------------------------------- |
| Console | `debug.verbosity(level)`                          |
| RPC     | `{"method": "debug_vmodule", "params": [number]}` |

### debug_vmodule

Sets the logging verbosity pattern.

| Client  | Method invocation                                 |
| :------ | ------------------------------------------------- |
| Console | `debug.vmodule(string)`                           |
| RPC     | `{"method": "debug_vmodule", "params": [string]}` |

#### Examples

If you want to see messages from a particular Go package (directory) and all subdirectories, use:

```js
> debug.vmodule("eth/*=6")
```

If you want to restrict messages to a particular package (e.g. p2p) but exclude subdirectories, use:

```js
> debug.vmodule("p2p=6")
```

If you want to see log messages from a particular source file, use

```js
> debug.vmodule("server.go=6")
```

You can compose these basic patterns. If you want to see all output from peer.go in a package below eth (eth/peer.go, eth/downloader/peer.go) as well as output from package p2p at level <= 5, use:

```js
debug.vmodule('eth/*/peer.go=6,p2p=5');
```

### debug_writeBlockProfile

Writes a goroutine blocking profile to the given file.

| Client  | Method invocation                                           |
| :------ | ----------------------------------------------------------- |
| Console | `debug.writeBlockProfile(file)`                             |
| RPC     | `{"method": "debug_writeBlockProfile", "params": [string]}` |

### debug_writeMemProfile

Writes an allocation profile to the given file. Note that the profiling rate cannot be set through the API, it must be set on the command line using the `--pprof.memprofilerate` flag.

| Client  | Method invocation                                           |
| :------ | ----------------------------------------------------------- |
| Console | `debug.writeMemProfile(file string)`                        |
| RPC     | `{"method": "debug_writeBlockProfile", "params": [string]}` |

### debug_writeMutexProfile

Writes a goroutine blocking profile to the given file.

| Client  | Method invocation                                         |
| :------ | --------------------------------------------------------- |
| Console | `debug.writeMutexProfile(file)`                           |
| RPC     | `{"method": "debug_writeMutexProfile", "params": [file]}` |