"code": "CannotModifyLockedTransaction",
	"target": "Unknown",
	"details": [
			"code": "CannotModifyLockedTransaction",
			"number": 1100,
			"message": "Modifying a locked document is not allowed.",
			"description": "Document -0- is locked. Modification is not allowed.",
			"faultCode": "Client",
			"helpLink": "",
			"severity": "Error"

A transaction that is Locked has been reported to a tax authority. Transactions that have been reported to a tax authority are maintained indefinitely for audit purposes and cannot be changed.

If a locked transaction needs to be adjusted, you must add a second journal entry reflecting the difference between the original transaction as reported and the corrected transaction. You can use the RefundTransaction API to create a reverse-charge journal entry.