Six Ways an S/4HANA Migration Goes Sideways

By Site Admin · September 1, 2026 · Page 3 of 4

The clearest example is the business partner. ECC keeps customers and vendors as separate objects. S/4HANA has one business partner model, tied to the old records through Customer-Vendor Integration, and moving to it is not optional. It also has to happen before the S/4HANA conversion itself

[8] . When one company exists as both a customer and a vendor, it should end up as a single business partner, which means matching records, settling conflicting details and deciding which version wins. That is a data governance problem more than a technical one, and it needs business sign-off [9] . Even numbering can bite: if Customer 1000 and Vendor 1000 are different companies, only one of them can keep 1000 as its business partner number [10] .

Ownership is the quiet issue underneath. Sales owns customers, procurement owns vendors, finance owns cost centers, and cross-domain cleanup stalls because nobody is responsible for the gaps

between them [11] . Settle who signs off what before the first load, not during the first mock run. 5. Treating testing and cutover as the last mile

When early phases run long, the back end of the plan is where the squeeze lands. One testing practitioner describes the mock migration as something you would typically repeat three to five times, fixing and re-running each round, before the data and configuration are clean enough for a full dress

rehearsal [12] . If your plan has a single mock run, it has a single chance to find what the other runs would have caught.

Test data is a second trap. Data that behaves in ECC doesn’t always carry over cleanly into S/4HANA’s model, where the Universal Journal replaces several finance tables. The result is parallel testing that nobody fully trusts: teams chase differences that turn out to be data problems while real defects go

unnoticed [13] . And the final cutover is often squeezed into a single weekend [13] , which is a poor moment to learn how long a load really takes. 6. Forgetting the people who use it

ECC authorizations are built around transaction codes and menus. S/4HANA with Fiori grants access through catalogs, groups and spaces instead. Copying ECC roles across unchanged is described as the most common security mistake in a migration. Roles need to be re-derived against the new app

inventory, segregation-of-duties rules re-checked, and GRC controls re-baselined [14] . Skip that and you spend the first weeks after go-live working through access tickets. Training belongs in the same bucket. The SAP Community post that lists late business involvement also names skills gaps and resistance to the Fiori interface as recurring problems [2] . People who can’t find where things went will invent workarounds, and workarounds are how ECC got messy in the first place. Putting it in order

Read together, the six suggest a sequence. Assess first, before anyone commits to a plan: readiness check, code scan, an honest look at the data. Choose the approach once you have seen the results, not before. Run data cleanup and code remediation side by side, each with a named owner. Then put the mock cycles and the test calendar into the plan before the build starts, and defend them when something else slips.

⬇ Download as a PDF