Having completed multiple SAP S/4HANA Conversions over the last years, we identified some patterns when it comes to S/4HANA and custom code:
1. Greenfield or Brownfield Approach for the S/4HANA Conversion?
While during the early days of S/4HANA most companies favored implementing their S/4 systems from scratch (aka Greenfield), nowadays most customers seem to be leveraging their strategic assets by selectively migrating customizations from their existing systems to their new S/4 systems. Regardless, it is not about green or brown, but what is right for your business!
2. Technical Upgrade or Functional Conversion?
In 9 out of our last 10 S/4HANA Conversion projects, 98% of the changes that were required to make existing custom code functional and performant in S/4 were purely technical. Only 2% required functional re-architecture. Most conversions are pure technical upgrades when it comes to custom code, even S/4!
3. Material Number Extension ; is it that bad?
On average more than 90% of the MATNR changes reported by Code Inspector/ATC are not relevant … but you need to know how to identify the ones that are! At smartShift, we leverage our automation platform to do this quickly and accurately.
4. Do I really need to touch all my custom code during S/4HANA Conversion?
On average between 40 – 70% of all custom developments in an SAP system have not been used within the last two years and can be decommissioned. This reduces the conversion effort to S/4HANA massively! We leverage our automation to do this without introducing risk or business impact!
5. Which SAP Notes really matter for my S/4HANA Conversion?
SAP Note 2215424 (Material Number Field Length Extension), 2198647 (S/4 HANA: Data Model Changes in SD) and 2431747 (General Ledger: Incompatible changes in S/4HANA compared to classic ERP releases) represent the vast majority of the total number of issues reported by Code Inspector/ATC. This might make you think that you would be better off with a greenfield approach and throwing away all your custom code. But again, it turns out that a huge portion of the reported issues do not in fact require any adjustments. On top of that, the remainder can be converted automatically!
6. HANA Database changes (the known issue)
Don’t be fooled: HANA is still a big deal when it comes to custom code and habits of old-school ABAP development. Our transformation projects show that the custom code in an average SAP system contains more than 5.000 HANA code compliance issues that can have a functional impact if not addressed (>90% ORDER BY issues). The good news: more than 94% can be transformed automatically!
7. Everything is faster on SAP HANA?
Move to SAP HANA DB and everything is faster? This is what your Business is expecting! But moving to SAP HANA without addressing performance issues in your custom code might even lead to performance degradation. For example, SELECT * is not a good thing on HANA. Everybody knows this. Our intelligent transformation engine can transform SELECT * where it is necessary and leave it where it does not matter, for example in customizing tables with less than 7 columns. On average we find more than 10.000 HANA Performance issues with SELECT * in our projects, and we fix more than 80% of them automatically!
8. SELECT SINGLE on HANA DB (the bomb is ticking…)
For the longest time the SAP community was not aware of the possible issues a SELECT Single statement can cause. Even today it still sounds rather exotic, but SELECT SINGLE (selecting only one record in a database table or view) can cause serious functional problems on SAP HANA. Take it seriously and fix all issues reported in Code Inspector Functional DB!
Conclusion
Although S/4HANA is formally not a successor of SAP ERP, its compatibility mode ensures that most of the custom coding still runs as before. Statistically only a small portion will not run anymore. It turns out, a S/4HANA conversion project can be seen as a technical transformation project after all.
Please contact us if you are considering the next step to S/4HANA, would like valuable insights from our experienced team, or want to learn more about smartShift’s S/4 automation platform!
Frequently Asked Questions
Why move from SAP ECC to S4 HANA?
Organizations move from SAP ECC to SAP S/4HANA because S/4HANA is SAP’s strategic platform for the future. It delivers faster performance, real-time analytics, simplified data models, and a modern user experience through SAP Fiori. More importantly, S/4HANA enables access to SAP’s ongoing innovations in cloud, automation, and AI. Staying on ECC increases technical debt and limits agility over time. Moving to S/4HANA helps enterprises modernize their core systems, improve operational efficiency, and remain competitive in a rapidly evolving business environment.
Which of the requirements must be met before converting from SAP ECC to SAP S4 HANA?
Before converting from SAP ECC to SAP S/4HANA, several key requirements must be met to ensure a smooth and low-risk transition. Organizations need a supported SAP ECC version and must complete Unicode compliance if not already done. A custom code analysis is essential to identify incompatibilities and technical debt that must be remediated. Data consistency checks, add-on compatibility validation, and preparation for the SAP HANA database are also required. Most importantly, companies need a clear migration strategy - greenfield, brownfield, or selective - aligned with business goals, timelines, and risk tolerance before starting the conversion.
Is SAP ECC being discontinued?
Yes. SAP ECC is being phased out as SAP shifts its full innovation and long-term investment to SAP S/4HANA. While ECC systems will continue to run, they will no longer receive new functionality or innovation. Organizations that remain on ECC face increasing risk, higher maintenance effort, and growing difficulty integrating with modern SAP technologies. As a result, SAP customers must plan a transition to S/4HANA to remain aligned with SAP’s roadmap, security standards, and future product strategy.
What is the deadline for migrating to SAP S/4HANA?
SAP has announced that mainstream maintenance for SAP ECC ends on December 31, 2027, with extended maintenance available until December 31, 2030, at a higher cost and with limitations. After 2030, ECC will no longer be supported. Because S/4HANA migrations are complex and can take several years - especially in heavily customized environments - organizations should begin planning and execution well ahead of 2027 to avoid risk, cost pressure, and last-minute disruption.
What are the benefits of moving to SAP S/4HANA?
Moving to SAP S/4HANA delivers both immediate operational improvements and long-term strategic value. S/4HANA’s in-memory architecture enables faster performance, real-time analytics, and simplified data models, helping teams make better decisions with up-to-date information. It also introduces a modern user experience through SAP Fiori, improving productivity and adoption. From a strategic standpoint, S/4HANA is SAP’s innovation platform - unlocking cloud, automation, AI, and continuous updates. By moving to S/4HANA, organizations can reduce technical debt, streamline processes, lower long-term IT costs, and position their SAP landscape for future growth and ongoing innovation.
