Successful migration to SAP HCM for S/4HANA

To secure the long-term viability of its SAP HCM system, Stadtwerke München (SWM) decided to upgrade to SAP S/4HANA.

The challenge was that their existing HCM system was highly complex and included numerous custom developments. SWM had largely managed the compatibility of these customizations in-house. However, SAP S/4HANA introduces new concepts that require adjustments to the existing system environment – such as the implementation of the SAP Employee Business
Partner model and the adaptation of custom code to the HANA database. FI-related changes also required updates to the payroll and payment processes in the HCM system.

With the goal of migrating without any loss of functionality, SWM chose an H4S4 brownfield migration approach. However, due to limited internal experience in this area, the company put the project out to tender.

Natuvion won the contract, thanks in part to its strong professional and technical collaboration with SWM on a parallel ILM project. In addition to providing migration support, Natuvion’s key task was knowledge transfer – ensuring SWM could build in-house expertise from the outset and take on as many tasks as possible independently

Foundation for migration success: careful project planning

When the migration project was launched in December 2023, the focus was on preparation – above all, system and data analysis. Using the SAP Readiness Check and the Simplification Items, the project team gained a comprehensive overview of the existing HCM system and the data and processes it contained. The ABAP Test Cockpit (ATC) check was also used to examine custom developments and determine which code adjustments were required for S/4HANA. These analyses formed the basis for all further steps.

In joint workshops, Natuvion and SWM coordinated on the best technical approach and developed a detailed conversion concept and a cutover plan. This laid the groundwork for the system conversion to begin.

Four steps to running H4S4

Using a system copy, Natuvion first technically migrated the existing SAP ERP – including the HCM landscape systems HRT (sandbox), HRI, HRK, and HRP – to SAP S/4HANA. In the next step, it activated SAP HCM for SAP S/4HANA on the target system and adapted it to meet individual requirements. This also included converting the central interface communication to Filegate, as well as making adjustments to the Fiori Launchpad user interface and house bank maintenance.

The third step involved setting up the Employee Business Partner function, which is essential for a successful H4S4 migration. This phase also focused on other necessary adjustments to ensure a smooth transition. Finally, the team carried out extensive technical and functional testing before the system was successfully moved into productive operation.

Successful foundation for HXM laid

The team successfully achieved its target of a go-live by the end of August 2024. Within just nine months, it migrated SAP ERP HCM to S/4HANA, while maintaining all existing day-to-day business functions and successfully introducing S/4-specific features such as the Employee Business Partner function.

A key factor in this successful project was the excellent collaboration between SWM and Natuvion. With a clear Jira board, topic-specific status meetings, and short-term updates via Microsoft Teams, the team ensured that all project participants were always kept informed and that issues could be resolved quickly.

Thanks to the SWM staff’s in-depth knowledge of their own system, they were also able to carry out many tasks themselves under Natuvion’s guidance. SWM’s IT project manager, Stefan Brandstätter, is very pleased with the outcome: “Natuvion was a great collaboration partner for us in every respect – not only in terms of project support, but also in internal knowledge building and quick issue resolution. This allowed us to meet our go-live date without any problems and puts us in a strong position for HXM and our continued journey to the cloud.”