Clean Core, or Why a Clean Core Is Important
Over time, many ERP environments become burdened by custom code, undocumented changes, and integrations that are difficult to maintain. This limits flexibility, slows down upgrades, and increases total cost of ownership. The Clean Core approach addresses these challenges by promoting the use of standardized, best-practice-aligned processes and enabling strategic enhancements for differentiation.
Process standardization supports our customers in their transition to SAP Business Suite, including the public cloud. It enables us to keep systems up to date through faster and more efficient upgrades for the private cloud, achieve faster innovation cycles, and simplify the adoption and use of AI. The focus is on creating resilient business processes supported by seamless integration, efficient workflows, and high data quality.
By adopting a clean-core approach, customers can:
- Accelerate innovation cycles
- Minimize technical legacy issues
- Simplify system maintenance and upgrades
Instead of limiting agility, Clean Core ensures that extensions are implemented correctly, with a focus on long-term stability, scalability, and the ability to innovate.
The further development of the three-tier model and the introduction of the Clean Core Level concept
SAP is further developing its extensibility guidelines with the Clean Core Level concept, a new model designed to simplify qualification criteria and provide a more pragmatic approach to managing user-defined code in SAP Cloud ERP Private as part of the transition to SAP Business Suite. Building on the previous 3-tier model, this new maturity model categorizes extensions into four different levels (A, B, C, and D) based on their architectural integrity, upgrade security, and compliance with the Clean Core principles.
This approach enables a more detailed assessment of an extension’s quality and upgrade stability and goes beyond a simple binary classification into “clean” and “unclean.” The core recommendation remains an “SAP BTP first” strategy aimed at the highest level, but the new model also takes into account the realities of complex system landscapes and helps customers tailor their Clean Core transformation to their specific needs. The fundamental principle remains unchanged: decoupling enhancements from the standard SAP code to ensure upgrade stability.
An overview of the four Clean Core stages
Each extension is evaluated using a standardized methodology that takes into account its structure, how well it is decoupled from the core, and how easily it can be updated or maintained.
Level A: Extension with SAP Build
Fully compliant extensions that use only publicly available and stable interfaces, which are guaranteed by formal stability contracts.
- Side-by-Side: Built on SAP BTP using pro-code and low-code tools for application development and process automation
- On-stack: Built within SAP Cloud ERP Private using the ABAP Cloud development model with publicly available APIs
Level B: Using traditional APIs
Use of traditional APIs – Utilization of traditional SAP APIs and technologies with clearly defined, documented, and generally upgrade-stable interfaces.
Level C: Access to internal objects
Partially compliant extensions based on internal SAP objects that offer flexibility for legacy scenarios.
To minimize upgrade risks, SAP provides a change log for SAP objects so that incompatible changes can be identified early on and upgrades can be planned proactively.
Level D: Extensions Not Recommended
Non-recommended extensions – Extensions that are not considered “clean” and explicitly use non-recommended objects or techniques (e.g., objects marked as “noAPI” in the Cloudification Repository, modifications to SAP objects, direct write access to SAP tables, or implicit extensions). These pose the highest risk and result in significant technical legacy issues.
Conclusion: Clean Core paves the way for strategic modernization
The Clean Core Level concept offers concrete benefits through:
- Differentiated assessment: A more nuanced, risk-based assessment of traditional ABAP code.
- Increased transparency: A clear distinction between low-risk “traditional APIs” and high-risk “not recommended” objects.
- Enabling a pragmatic path forward: Helping customers manage their existing codebases more effectively and prioritize corrective actions, with an initial focus on the highest-risk extensions (Level D).
The Clean Core Level concept does not alter the ultimate goal: building decoupled, upgrade-stable extensions, with Level A representing the ideal. Instead, it provides a more practical and transparent framework for achieving this goal. It enables companies to make informed decisions, understand the specific risks associated with their custom code, and strategically plan their modernization efforts. By prioritizing the elimination of Level D extensions and leveraging the greater transparency in Levels B and C, customers can reduce technical debt, simplify future upgrades, and maintain the long-term integrity and agility of their SAP S/4HANA core system.
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