Mastering SAP S/4HANA Migrations

Strategies for Overcoming Data, Customisation, and Organisational Challenges

I remember a time when I was working on a high-stakes SAP implementation and the team felt so confident heading into user acceptance testing—until one glaring error halted our progress. Some customers’ addresses were completely incorrect, leading to a postponed go-live and frantic days spent investigating the cause. It turned out that relying on Excel for data preparation within the “Migrate Your Data” Fiori app left us with no change log. This meant that when errors appeared, no one could pinpoint who made the mistake or when it happened, and our confidence in the entire data migration process began to waver.

This kind of ordeal underscores the complexities of SAP S/4HANA conversions. According to The Hackett Group, organisations face a series of challenges when converting from SAP ERP (ECC) to S/4HANA, including lack of organisational planning, complex data migration, and insufficient testing. Given the 2027 deadline for moving to S/4HANA, project managers must navigate these challenges with clear strategies and proper guidance.

In this blog post, I want to highlight the lessons I’ve learned from these experiences and the insights gleaned from The Hackett Group’s findings. For SAP project managers, the problems are real, pressing, and multi-faceted. By focusing on data migration complexities, balancing custom code with standardisation, and managing organisational change effectively, we can help ensure smoother SAP S/4HANA transitions—and avoid the kind of setbacks I once faced.

Why SAP S/4HANA Conversion Matters

SAP S/4HANA is not just a newer version of SAP ERP (ECC); it introduces a more streamlined, real-time data processing architecture that promises faster analytics, simpler data models, and an array of capabilities designed to meet modern business demands. However, as we race towards the 2027 deadline, many organisations still find themselves grappling with how to effectively switch from ECC to S/4HANA. The Hackett Group identifies five major challenges—organisational disorganisation, source system preparation, data transfer complexity, custom code management, and insufficient testing—all of which can derail even the most well-intentioned project.

My own anecdote about the wrong address migration during user acceptance testing highlights just how critical it is to have robust processes. Data oversights or incomplete testing can seriously affect stakeholder trust, derail your timeline, and add unnecessary costs to an already resource-intensive project.

In the sections that follow, I will explore three pressing issues for SAP project managers—data migration, customisation vs. standardisation, and organisational change management—each woven into the larger tapestry of S/4HANA conversion. Drawing upon the article’s insights and my own experience, I’ll offer practical approaches for tackling these challenges head-on.

Navigating Data Migration Complexities in SAP S/4HANA Implementations

Data migration sits at the heart of any ERP transformation. For SAP S/4HANA, it’s particularly challenging because of the structural and architectural differences between SAP ECC and S/4HANA. Millions of records often need to be moved or transformed, and as The Hackett Group notes, “Moving data from SAP ERP (ECC) to S/4HANA is challenging if you don’t properly prepare for conversion.” When data is incorrectly mapped or accidentally altered during extraction, transformation, or loading (ETL), you risk major project delays and a breakdown of trust among users.

Practical Strategies

Early Data Assessment: Begin with a thorough data profiling exercise. Identify data quality issues (duplicates, incomplete records, outdated information) and address them long before migration starts.
Use SAP’s Recommended Tools: The SAP S/4HANA Migration Cockpit and the “Migrate Your Data” Fiori app streamline processes, but they also highlight how crucial version control and logs are. My own experience taught me the pitfalls of Excel-based preparation without a proper audit trail. Where possible, rely on built-in SAP tools that log activities.
Set Up a Governance Framework: Establish a data migration governance team to oversee roles, responsibilities, and decision-making. This includes naming who is responsible for approvals, who oversees data cleansing, and how issues are escalated.
Phased Migrations & Pilot Projects: Rather than migrating all data at once, consider phased approaches that allow you to learn from a pilot group of data sets. This helps you correct mistakes early and refine processes for subsequent waves.
Automated Testing & Validation Checks: Implement automated scripts to validate that data moves correctly. For instance, if you migrate customer addresses, run targeted checks to ensure data fields, postcodes, and city names match expected values. Automated comparison reports can be immensely helpful.

Short Case Study
In one project, our team decided on a phased approach for sales data. We first migrated a small subset of historical transactions to the development environment. Automated validation scripts flagged inconsistencies in currency codes that had been incorrectly formatted during the transformation step. Because of this early detection, the broader migration to the quality environment was significantly more accurate. This early pilot helped us avoid the kind of go-live setback I once faced with address data errors.

Balancing Customisation and Standardisation in SAP S/4HANA Projects

Custom code is the lifeblood of many SAP implementations, shaping functionalities that cater to unique business processes. However, too much custom code can slow system performance, increase maintenance costs, and complicate upgrades. On the other hand, if you choose to rely solely on out-of-the-box SAP solutions, you may be forced to bend your existing processes, possibly losing valuable unique differentiators. A PwC statement reads, “Custom code developed in previous systems should be thoroughly tested in the new environment,” emphasising the delicate balance that project teams must strike.

Practical Strategies

Custom Code Inventory: Begin by creating an inventory of all custom developments in your ECC environment. Classify them based on business criticality and frequency of use. If a custom solution isn’t used regularly or is no longer aligned with current business strategies, consider retiring it.
Adopt SAP Standard Where Possible: SAP S/4HANA includes new standard functionalities that might replace your current custom solutions. Evaluate these carefully. Migrating to a standard solution can often reduce technical debt, cut maintenance costs, and align you with SAP’s innovation roadmap.
Refactor vs. Re-Implement: For codes that need to remain, assess whether a simple refactoring is enough to align with S/4HANA’s simplified data structures, or if a re-implementation is required to harness new functionalities.
Leverage Extensions and BAdIs: SAP S/4HANA provides extension mechanisms (In-App and Side-by-Side Extensions) that help you tailor your system without modifying the core. Business Add-Ins (BAdIs) and the SAP Cloud Platform Extension Factory are powerful tools that keep your customisations modular, easier to upgrade, and better integrated with SAP’s code lifecycle.
Collaborate with Key Stakeholders: The decision to retain or discard a custom feature isn’t purely a technical one; it’s a strategic business decision. Engage functional managers, business process owners, and IT teams in a collaborative workshop to weigh costs, benefits, and future implications.

Short Case Study
A manufacturing company with highly specialised production processes found themselves over-reliant on custom code that had been built up over a decade. When preparing for the S/4HANA conversion, they discovered that half of their legacy code was no longer necessary due to S/4HANA’s expanded standard features. By pruning unnecessary custom objects and refactoring the truly critical ones, they dramatically reduced future technical debt, saving both development and support costs in the long term.

Overcoming Organisational Change Management Challenges in SAP S/4HANA Transitions

Technology migrations often fail or stall for reasons unrelated to technology. Resistance to new processes, inadequate training, or poor communication can send even the best S/4HANA project off track. According to Oxford Global Resources, “Transitioning to SAP S/4HANA brings forth potential disruptions attributed to inadequate change management.” Because S/4HANA transitions often affect core business processes, ensuring stakeholder alignment and user readiness is as critical as the technical migration itself.

Practical Strategies

Stakeholder Engagement: Identify all relevant stakeholders—executives, department heads, end-users, and IT teams—and keep them informed about changes, timelines, and potential impacts. Early buy-in can preempt pushback and build excitement around new possibilities.
Structured Communication Plan: Develop a clear communication roadmap. Outline what messages will be shared, when, and through which channels (e.g., newsletters, lunch-and-learns, or online forums). Transparency about project milestones and challenges builds trust.
Comprehensive Training Programmes: Many users resist change simply because they lack confidence in new systems. Provide hands-on training sessions, e-learning modules, and sandbox environments. For instance, if a finance team is used to T-codes, help them understand how transactions are streamlined in Fiori-based apps.
Define New Roles and Responsibilities: S/4HANA’s new modules or functionalities might change the nature of certain roles. Clearly define who owns what processes, and update performance metrics to reflect new responsibilities.
Celebrate Quick Wins: Identify smaller milestones where you can demonstrate the benefits of S/4HANA (e.g., faster reporting times, simpler user interfaces). Spotlighting these successes encourages further user adoption.

Short Case Study
In one multinational implementation, the team discovered that a significant percentage of users found the new Fiori apps daunting. A well-structured combination of e-learning courses, live workshops, and a ‘buddy system’ where experienced users guided newcomers helped boost confidence. Within three months, user adoption skyrocketed, and the project overcame early negativity.

Weaving It All Together: My Personal Experience

My anecdote about go-live being postponed reminds me of the interconnected nature of these challenges. A data issue (wrong address migration) also became a matter of organisational trust: once users saw incorrect data, they began doubting the entire system. The setback could have been mitigated by:

Robust data governance and version control (to see who made the changes and when).
Adequate testing on each iteration of data loads, rather than waiting until the end.
Clear communication so end-users understood the process and had a way to raise red flags early.

Despite the frustration and delay, the experience led to a more disciplined approach. We refined our data migration checks and invited more user feedback loops. By the time we went live, users felt assured that our data validation was airtight. This underlines how each of the three major challenges—data migration, custom code decisions, and change management—must be addressed holistically.

The path to a successful SAP S/4HANA conversion is undeniably complex, but it’s a worthwhile journey that delivers long-term benefits. By 2027, organisations still on SAP ECC will either have to confront these challenges head-on or risk falling behind in a marketplace that demands agility, real-time insights, and streamlined processes.

From my own experience, the greatest lessons revolve around thorough planning, consistent testing, and transparent communication. The transition from ECC to S/4HANA is more than a technical upgrade—it’s a pivotal shift in how businesses operate. As we’ve explored, data migration can be an Achilles’ heel if overlooked, custom code can become a burden if it’s not properly evaluated, and your people can make or break the project if they’re not guided through the change.

Addressing the three core challenges—navigating data migration complexities, balancing customisation with standardisation, and overcoming organisational resistance—requires a blend of solid technical expertise and empathetic human leadership. Leveraging standard features and cutting-edge tools is half the battle; the other half is building a culture that embraces continuous improvement and collaboration.

With these strategies in mind, SAP project managers are well-equipped to deliver a smooth, timely, and effective S/4HANA conversion. Success is possible if you approach it systematically, engage stakeholders, and champion proactive measures every step of the way.

I’d love to hear your experiences! Share your thoughts or questions in the comments, and let’s keep this conversation going.

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