Data Migration Failures: The Quiet Killer of S/4HANA Projects

The mechanics of why this happens are not exotic. Moving from ECC to S/4HANA is not a simple copy job; it requires genuine data cleansing, enrichment and verification, because S/4HANA's data model is meaningfully different from ECC's, particularly around finance's Universal Journal. Years of accumulated exceptions, workarounds and inconsistent master data in a legacy ECC system — duplicate vendor records, inconsistent unit-of-measure conventions, stale customer master data — all surface at once during a migration, usually later than the project plan assumed.

Test data compounds the same problem from a different angle. A full client copy from production, needed to build a realistic test environment, can take hours to days depending on data volume, and the post-copy work — masking sensitive data, validating configuration, setting up users, checking integrations — adds more time on top. By the time that environment is actually ready, the live configuration has often already drifted, because the program kept moving while the copy was running. Teams end up refreshing test environments repeatedly, each refresh eating into a schedule that was already tight.

None of this is a reason to fear data migration — it's a reason to fund it properly and start it early. The organizations that avoid becoming part of that 65% figure are the ones that treat