Replenishment object &1 cannot be assigned

What causes this issue?

Object &V1& could not be assigned. The assignments to the next higher
assembly material &V2&, object &V3& could not be found.
This could be caused by a program error or a process that is not
supported.

System Response

Processing continues.

How to fix this error?

In transaction <ZH>PEG05</>, check whether all objects are assigned
correctly. Because of this error, objects are partly assigned to the
WBS element for excess on plant level.
Inform the person responsible for the process of this problem or
contact SAP.

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.