Uniqueness mandatory as long as there are HU-managed storage locations

What causes this issue?

The uniqueness of the number assignment cannot be revoked as long as
there are storage locations in the system that are flagged as
<LS>HU-managed storage locations</>. Handling units can only function
if HU number assignment is unique.

System Response

Uniqueness cannot be revoked.

How to fix this error?

If having the packing function for outbound deliveries is sufficient
for you, delete the HU management in the storage locations. However, if
you want to work with non-assigned handling units, use a number range
interval or an SSCC18 to guarantee unique number assignment of handling
unit IDs.

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.