HU &1: Status prohibits HU change

What causes this issue?

You are attempting to change a blocked handling unit (HU).

System Response

Repacking and other movements into or out of a handling unit are not
allowed. The system issues an error message. The HU has one of the
following status:
Goods Issue Posted
Loaded
Content Changes Blocked
Customs Block
Lock for Delivery

How to fix this error?

If the HU has the status <ZK>Loaded </>and the handling unit was loaded
without a warehouse task, first cancel the loading of the handling unit.
If the HU has the status <ZK>Loaded</> and the handling unit was loaded
with a warehouse task, unload the handling unit.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.