trace_replayTransaction

The trace_replayTransaction method allows you to replay a transaction and retrieve a variety of trace information including execution trace, VM trace, and state changes. This method provides more detailed information than trace_transaction by showing how the transaction changed the state.

Use Cases

• Debugging complex transactions with state changes
• Analyzing gas consumption for optimization
• Tracing internal calls between contracts
• Understanding how storage was modified by a transaction
• Verifying the execution of complex logic flows
• Security auditing with full state transition detail
• Analyzing revert reasons with detailed context
• Investigating memory and storage access patterns
• Validating contract behavior as part of audit reviews
• Optimizing contract code based on execution patterns

Method Details

This method replays a transaction and returns detailed trace information including VM trace and state differences.

Response Example

{
	"jsonrpc": "2.0",
	"id": 1,
	"result": {
		"output": "0x0000000000000000000000000000000000000000000000000000000000000001",
		"stateDiff": {
			"0x1234567890123456789012345678901234567890": {
				"balance": {
					"*": {
						"from": "0x100",
						"to": "0x110"
					}
				},
				"code": "=",
				"nonce": {
					"*": {
						"from": "0x10",
						"to": "0x11"
					}
				},
				"storage": {
					"0x0000000000000000000000000000000000000000000000000000000000000001": {
						"*": {
							"from": "0x0000000000000000000000000000000000000000000000000000000000000000",
							"to": "0x0000000000000000000000000000000000000000000000000000000000000001"
						}
					}
				}
			}
		},
		"trace": [
			{
				"action": {
					"callType": "call",
					"from": "0x83806d539d4ea1c140489a06660319c9a303f874",
					"gas": "0x1a1f8",
					"input": "0x",
					"to": "0x1c39ba39e4735cb65978d4db400ddd70a72dc750",
					"value": "0x7a16c911b4d00000"
				},
				"result": {
					"gasUsed": "0x2982",
					"output": "0x"
				},
				"subtraces": 2,
				"traceAddress": [],
				"type": "call"
			}
		],
		"vmTrace": {
			"code": "0x606060...",
			"ops": [
				{
					"cost": 3,
					"ex": {
						"mem": null,
						"push": ["0x60"],
						"store": null,
						"used": 16723979
					},
					"pc": 0,
					"sub": null
				}
			]
		}
	}
}

Trace Types

The traceTypes parameter accepts an array of the following values:

• trace: The basic trace of transaction execution
• vmTrace: A detailed trace of the EVM execution
• stateDiff: State changes resulting from the transaction

You can request any combination of these trace types.

State Diff Format

The state diff format uses the following symbols:

• "=": No change in the value
• "+": The value was created
• "-": The value was deleted
• "*": The value was modified, with "from" and "to" values

Important Notes

• This method requires trace APIs to be enabled on the Ethereum node
• Not all Ethereum clients support this method (primarily OpenEthereum/Nethermind)
• The response can be very large, especially with vmTrace enabled
• For simple trace information without state changes, use trace_transaction instead
• The method is computationally intensive and may take time to complete
• Historical transactions can only be traced if the node maintains archive data
• Different traceTypes significantly affect response size and computation time
• For debugging simpler transactions, trace_transaction may be sufficient
• State diffs are particularly valuable for understanding storage changes
• Transactions that revert will show state changes up to the revert point

See also

• trace_transaction - Retrieve basic traces for a transaction
• trace_replayBlockTransactions - Replay and trace all transactions in a block
• trace_call - Execute and trace a call without creating a transaction
• debug_traceTransaction - Alternative detailed transaction tracing