Why SAP S/4HANA data migrations often take longer than planned

A six-month project timeline, everything on track: The technical migration is complete, the systems are configured, and the go-live date is approaching. And then comes the moment when someone asks, “What about the data?” What follows is all too familiar to many project managers: The schedule slips, additional resources are needed, and costs escalate. Not because of the technology, but because of the data. More specifically: because of duplicates, a lack of governance, and an SAP Business Partner conversion that turns out to be significantly more complex than anticipated.

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In most SAP S/4HANA projects, data migration is the area with the highest risk of delays – not because suitable tools are lacking, but because data quality in the source systems is rarely as good as everyone involved tacitly assumes. This article highlights the typical pitfalls in data migration to SAP S/4HANA and how you can address them.

Pitfall #1: Duplicates that no one was aware of

In an ERP system that has grown over the years, duplicate data records inevitably accumulate. Customers created under slightly different names, suppliers with multiple entries per location, material master data with inconsistent descriptions. In day-to-day operations, this often goes unnoticed because employees know which record is the correct one.

During migration to SAP S/4HANA, this implicit knowledge no longer works. At the latest when merging customers and vendors into SAP Business Partners, these legacy issues surface. And then the question arises: Which record is transferred? Which records are merged? And who decides that?

The solution lies not in the migration tool, but in systematic data cleansing prior to the actual migration project. This means: Identifying duplicates, defining rules for merging, and coordinating with the business units. Anyone who waits until the migration to do this is guaranteed to lose time.

Pitfall #2: Lack of data governance

Many companies lack clearly defined responsibilities for their master data. There is no binding definition of what a customer master record should look like, which fields are required, and who is authorized to approve changes. The result: Each department maintains data according to its own rules, and over the years, this leads to a proliferation of inconsistent data that comes back to haunt the company during a migration.

SAP S/4HANA is less forgiving in this regard than the former SAP ECC system. Fields that were previously optional are now mandatory. Data types that were previously tolerated now result in errors. Those who migrate without a solid governance structure face a choice: either manually rework thousands of records or live with poor data quality in the new system.

The better approach: Establish data governance well in advance of the migration. This doesn’t have to be a massive undertaking. Often, it’s sufficient to define clear rules for the most important data objects (customers, suppliers, materials), designate data owners, and implement simple quality monitoring. This groundwork pays off not only during the migration but also in day-to-day operations.

Pitfall #3: Underestimating the SAP Business Partner migration

In SAP ECC, accounts receivable (customers) and accounts payable (vendors) were separate master data objects. In SAP S/4HANA, this distinction no longer exists. Both objects are consolidated under the unified SAP Business Partner concept. What sounds logical and modern in theory is, in practice, one of the most time-consuming aspects of data migration.

The challenge lies not only in the technical migration. It involves reevaluating existing processes: Which roles are assigned to which business partners? How are customers handled who are also suppliers? What happens to historical documents?

Based on our consulting experience, we can say that the SAP Business Partner implementation typically takes longer than originally planned. This is especially true if the data is not clean (see pitfalls #1 and #2). Starting a pilot run early and carefully reviewing the results helps avoid unpleasant surprises just before go-live.

What sets successful projects apart

Data migration projects that stay on schedule and within budget typically have one thing in common: they treat data quality not as a side task, but as a separate subproject. Specifically, this means that data migration is identified as a critical path as early as the planning phase. There is a dedicated team that handles data cleansing, mapping, and test migrations. And it is accepted that data work takes time that cannot be shortened.

Furthermore, successful projects invest in test migrations. Not one, not two, but as many as necessary until the results are correct. Each test migration uncovers problems that cannot be foreseen in advance. The sooner they are identified, the more cost-effective the solution.

And finally: The business departments must be involved. Data quality is not purely an IT issue. The business departments know which data is correct, which is outdated, and which belongs together. Without this knowledge, no migration will run smoothly.

Conclusion: Data quality – from a nice-to-have to a must-have

Data migration is often a massively underestimated factor in SAP S/4HANA projects. Technically, the necessary tools are available; methodologically, there are proven best practices. What is missing in many projects is a realistic assessment of the effort involved and the willingness to invest in data quality before the actual migration tool is even deployed.

Those who are aware of the pitfalls described above and address them early on not only avoid delays and additional costs. They also lay the foundation for an SAP S/4HANA system that works with reliable data from the start – and thus for all other topics such as reporting, automation, and artificial intelligence.