Custom Code Remediation
Custom code is often the biggest variable in S/4HANA transitions. Understanding your code footprint and remediation approach is critical to realistic planning.
of project effort typically
inventory → classify → remediate → test
may be retired
analysis is critical
Why Custom Code Is the Critical Path
In many S/4HANA transitions, custom code remediation consumes 40-60% of project effort and is the primary source of timeline risk. Underestimating this workstream is one of the most common causes of project delays and budget overruns.
S/4HANA introduces significant changes: simplified data models, deprecated functions, new APIs, and HANA-specific syntax requirements. Custom code that worked perfectly in ECC may fail to compile, perform poorly, or produce incorrect results in S/4HANA.
The good news: with proper analysis and a structured approach, this is a manageable workstream. The key is starting early, classifying ruthlessly, and automating testing.
Common Mistake
"We'll handle custom code in parallel with testing." — This almost always leads to delays. Start code analysis 6-12 months before conversion.
Last Updated
January 15, 2026
Sources
- •SAP Simplification List
- •SAP ATC Documentation
Information based on publicly available SAP documentation and industry sources. For the latest details, consult SAP official materials or qualified partners.
What Makes Code Incompatible
Simplified Data Models
S/4HANA consolidates tables. Code referencing old tables (BSEG, KONV, etc.) may break.
Deprecated Functions
Many function modules and BAPIs are removed or replaced with new APIs.
Business Partner
Customer/Vendor master replaced by Business Partner. All related code needs review.
Material Ledger
Material Ledger mandatory in S/4HANA affects costing and valuation code.
HANA Syntax
Native SQL, OpenSQL changes, and HANA-specific functions require adaptation.
Unicode Compliance
All code must be Unicode-compliant—check older legacy programs.
The 4-Step Remediation Process
Inventory
2-4 weeks
Key Activities
- •Run SAP Readiness Check to identify impacted objects
- •Use ATC (ABAP Test Cockpit) with S/4HANA check variants
- •Extract full list of Z* objects with usage data
- •Identify third-party add-ons and their dependencies
Output
Complete inventory with severity classification
Classify
2-4 weeks
Key Activities
- •Categorize: Must fix / Should fix / Can retire
- •Map objects to business processes and criticality
- •Identify "dead code" (no usage in 12+ months)
- •Assess effort per object (auto-generated estimates)
Output
Prioritized remediation backlog
Remediate
3-12 months
Key Activities
- •Fix syntax issues and simplification items
- •Replace deprecated functions with new APIs
- •Adapt to new data models (compatibility views or rewrites)
- •Retire unused code (with governance approval)
Output
S/4HANA-compatible codebase
Test
Continuous
Key Activities
- •Unit test each remediated object
- •Integration test affected business processes
- •Regression test full scenarios
- •Performance test critical transactions
Output
Validated code ready for production
Understanding Simplification Items
SAP's documented list of changes affecting custom code
SAP publishes a "Simplification List" documenting every change that could affect custom code. This is your primary reference for understanding what needs to change. The list grows with each S/4HANA release.
Common Categories
Table/View Changes
Tables consolidated or replaced (e.g., BSEG → ACDOCA)
Function Module Obsolescence
FMs removed or replaced with new APIs
Business Logic Changes
Mandatory new features (Material Ledger, Business Partner)
Compatibility Options
- A
Compatibility Views
SAP provides views that mimic old structures—use short-term
- B
Released APIs
SAP-recommended replacement interfaces
- C
Custom Rewrite
Full redesign using new S/4HANA capabilities
Tools for Custom Code Analysis
SAP-Native Tools
SAP Readiness Check
High-level impact assessment and sizing
ABAP Test Cockpit (ATC)
Detailed code analysis with S/4HANA check variants
Custom Code Migration Worklist
Prioritized remediation tracking in Fiori
SAP Business Technology Platform
Remote custom code analysis via BTP
Partner/Third-Party Tools
Panaya
Cloud-based impact analysis and testing
Tricentis
Automated testing for regression validation
Basis Technologies
Automated code remediation and transport
Virtual Forge / SAST Tools
Security-focused code analysis
Custom Code Governance
During Transition
- Establish code review board for retire/remediate decisions
- Set clear criteria for retirement (no usage, duplicate, etc.)
- Track remediation velocity weekly
- Block new Z* development unless S/4-ready from start
- Document all changes for audit trail
Post Go-Live (Clean Core)
- Enforce clean core principles for new development
- Prefer extension points over modifications
- Use released APIs only
- Regular ATC scans for new code
- Track custom code metrics in ops reporting