View/table was added to customizing object manually in SOBJ piece list

What causes this issue?

The table/view was added to the object manually when the BC Set or
request was created. It is not part of the object definition (see
transaction SOBJ).

System Response

The BC Set display/maintenance transactions display the table/view as
part of the customizing object. The activation procedure also regards
the table/view as part of the customizing object, and activates it, such
that table entries are created/updated.

How to fix this error?

Usually SOBJ definition is generated succeeding maintenance view
generation process.
A table/view is usually only added manually to customizing object after
initial generation, if it is missing in the object definition (SOBJ)
piece list. If it shall be part of the maintenance object, the object
must be added in the object piece list in SOBJ.
Compare the SOBJ transaction object piece list with the Data Dictionary
(SE11) piece list, and resolve differences in the object piece list.
Choose the 'Compare with Dictionary' pushbutton in SOBJ. This pushbutton
is only active in change mode.
For cluster objects, you must correct the object lists of the sub
objects first.
If the table/view is independent of maintenance object definition (data
can be populated with application exits, i.e., Maintenance Events or
Custom modules), this is a legitimate way of putting an
object-independent table/view in the BC Set. There is not yet any other
way of putting such a table/view in BC Sets, independently of an object.
In this case, raise an exemption for the ATC, if application exits are
handling the data population explicitly for an added table/view in SOBJ.

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.