How To Fix ARS_CMP_ATC021 - Object was changed incompatibly regarding its system-internal use (C1).

SAP Error Message - Details

• Message type: E = Error

• Message class: ARS_CMP_ATC - API Release: Compatibility Checks – ATC Messages

• Message number: 021

• Message text: Object was changed incompatibly regarding its system-internal use (C1).

What causes this issue?

Incompatible changes were detected in a development object which was
released as API for system-internal use (compatibility contract C1).

System Response

Each released API is checked for incompatible changes between releases
depending on the assigned compatibility contract. Those checks comprise
of <ZK>basic checks </>(e.g. detection of deleted elements) and
<ZK>domain-specific checks </>(e.g. detection of annotation changes in
CDS views) by different application components.

How to fix this error?

Each check message describes an incompatible change in a development
object which was released as API.
<ZH>Note</>: If the checked development object is a package, the check
messages refer to objects which were formerly contained in this package
but were deleted although they have been released as APIs.
Undo this incompatible change by restoring the affected part of the API
in the way it was previously shipped to the customer.
Example
An element was removed from the projection list of a released CDS view.
If this element is used in a customer-specific CDS view based on the
released CDS view, this would cause ABAP dictionary activation errors
during the upgrade of the customer system.
<ZK>Check message</>: Element <ElementName> was removed.
<ZK>Remedy</>: Add this element to the projection list again, using the
same data type as before.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.