Why has SAP shifted its architectural guidance toward a Clean Core philosophy?

Historically, many SAP customers accumulated deep, direct modifications to core ABAP objects over years of customization — which worked, but made every SAP upgrade a genuinely risky, expensive project, since modified core code could conflict with or be overwritten by SAP's own updates, requiring extensive re-testing and manual reconciliation each time.

flowchart LR
    A[Heavy core modifications] --> B[Every SAP upgrade requires extensive re-testing/reconciliation]
    C[Clean Core: extensions kept separate] --> D[Upgrades apply more smoothly, extensions largely unaffected]

Clean Core directly addresses this by design: keeping the core unmodified means SAP's continuous updates (especially frequent in cloud releases) can apply smoothly, since there's no custom code embedded in the core to conflict with them. This is also foundational to SAP's broader cloud strategy — a genuinely "evergreen," continuously updated cloud system is only practical if customers aren't deeply modifying the core it's built on.