Subobjects of object &1 have no customizing delivery class

What causes this issue?

The object &V1& of type '&V2&' ('V' = view or 'S' = table with text
table) contains at least one subobject (table), which has an
inapproprate delivery class for customizing data, or is flagged as
system object.
Tables/views which are used in the object &V1&, and are
customizing-relevant, must not be system objects (e.g. table T000,
TADIR, CVERS, ...), and must have one of the following delivery classes
(transaction SE11):
'C': customizing table, maintained by customers, not an SAP import
'G': customizing table, protected against SAP UPD, only INS allowed
'E': control table, SAP and customers have their own key areas
SPACE: is also accepted as a customizing delivery class
<ZK>System objects: </>System objects are tables which are either in the
ABAP Dictionary, or are used as internal tables by the SAP system. They
cannot be transported, so they cannot be used in BC Sets.

System Response

Table/view &V1& is forbidden in the customizing environment (and thus
also in BC Sets), because not all subobjects have a customizing delivery
class, or some of them are system objects.
Object &V1& may already have been put in BC Sets, because of a missing
check in the BC Set maintenance transaction. In this case, the object
can be activated, if there is no other reason why not, but the
subobjects (tables) are not interpreted as "Customizing" when they are
put in a transport request (BC Set activation), which may cause problems
in subsequent systems. System objects cannot be put in transport
requests.

System Response

The table/view &V1& is forbidden in BC Sets, because not all subobjects
have a customizing delivery class.

How to fix this error?

Check the delivery class of all tables/views in the object &V1&. You can
see the tables in views and tables with text tables (S tables) directly
in the DDIC transaction SE11.
You must change the delivery class of the subobjects, to be able to use
the object for customizing data. Contact the SAP developer responsible.
If all subobjects have a customizing delivery class and this message
still appears,at least one table is a system object. In this case,
object &V1& cannot be pit in the BC Set.

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.