We’re migrating material master data from ECC to S/4HANA 1809 using Migration Cockpit and hitting critical validation failures. Automated QA test scripts are consistently failing on migrated material records, with validation logs showing missing or invalid Unit of Measure (UoM) fields across multiple material types.
The puzzling part is our Migration Cockpit mapping templates appear correct - we’ve triple-checked base UoM, alternative UoM, and conversion factors. Yet post-migration validation keeps flagging materials with error code MM_UOM_003. We’ve migrated about 45,000 material records, and roughly 12% are failing validation.
Migration Cockpit shows green status for all mapping rules, but the actual data in S/4HANA tables has inconsistencies. Has anyone encountered similar UoM validation issues where mapping looks correct but data migration still fails? We’re blocked from proceeding to next migration wave.
The issue isn’t your Migration Cockpit mapping - it’s the underlying data validation framework in S/4HANA being more restrictive than ECC. Your automated QA test failures are exposing three systematic problems that need addressing before proceeding:
Problem 1: Missing UoM Master Data
Validation logs showing MM_UOM_003 indicate that while your materials reference specific UoMs, those UoM definitions don’t exist in S/4HANA’s T006 table. This happens when ECC has custom or legacy UoM codes that weren’t included in your initial system configuration migration. Solution: Extract all unique UoM codes from your failing materials using transaction SE16 on MARM table, then verify each exists in S/4HANA T006. For missing codes, either create them manually in S/4HANA (transaction CUNI) or map them to standard ISO codes in your Migration Cockpit value mapping.
Problem 2: Conversion Factor Precision Mismatch
S/4HANA enforces stricter decimal precision rules than ECC for UoM conversion factors, especially for materials in regulated industries. Even though Migration Cockpit shows green status, the actual data being written violates S/4’s validation rules. Export your failing materials and check their conversion factors in ECC table MARM - look for entries with more than 5 decimal places or very small numbers (less than 0.00001). These need to be cleansed in ECC before migration or handled with custom conversion logic in your migration project.
Problem 3: Material Type vs UoM Group Incompatibility
S/4HANA’s material type configuration (transaction OMSA) has stricter rules about which UoM groups can be assigned to which material types. Your Migration Cockpit mapping appears correct because it’s syntactically valid, but the data combinations violate S/4’s semantic validation rules. Compare your ECC and S/4HANA material type configurations - specifically the allowed UoM groups per material type. You may need to either adjust material type assignments during migration or expand allowed UoM groups in S/4HANA configuration.
Recommended Resolution Path:
Run SAP Note 2769355 to update Migration Cockpit templates with enhanced UoM handling
Execute data quality report RM06EEU0 in ECC to identify all UoM inconsistencies before migration
Create pre-migration cleansing script to standardize conversion factor precision
Add value mapping rules in Migration Cockpit to convert legacy UoM codes to S/4HANA standard codes
Update your automated QA tests to validate not just data presence but also S/4HANA semantic rules
Consider implementing SAP Master Data Governance for ongoing UoM data quality if not already in place
This systematic approach should resolve your 12% failure rate and prevent similar issues in future migration waves. The key insight is that Migration Cockpit validates mapping correctness but doesn’t fully validate S/4HANA’s stricter data quality rules - that’s what your automated QA tests are correctly catching.
This draft is based on general SAP S/4HANA knowledge. It has not been verified against your specific version and environment. Practitioners: verify the steps and share your experience below.
Check your source data quality in ECC first. We had identical symptoms last year - Migration Cockpit mapping was perfect, but source UoM tables in ECC had orphaned records. Run transaction SE16 on T006 and T006A tables to verify UoM definitions exist for all materials being migrated. Also check MARM table for alternative UoM entries that might reference deleted or invalid units.
Confirmed this resolves MM_UOM_003 errors — after populating missing UoM definitions directly in T006 via SM30 before re-running Migration Cockpit, our material master loads completed cleanly.
The 12% failure rate suggests systematic data quality issues rather than mapping problems. I’d recommend running SAP Readiness Check tool specifically for material master migration - it has built-in validations for UoM consistency that often catch issues Migration Cockpit misses. Also verify your ISO code mappings between ECC and S/4HANA. The UoM framework changed significantly in S/4, and some legacy unit codes don’t have direct equivalents. You might need custom conversion logic for industry-specific units.
Error MM_UOM_003 specifically relates to missing conversion factors in MARA-MEINS relationships. Your automated QA tests are correctly catching the issue. Export the failing material numbers and run report RM06EEU0 in ECC to check for conversion factor gaps before migration.
We faced this exact scenario during our 1809 migration. The root cause was decimal precision differences in conversion factors between ECC and S/4HANA. ECC allows up to 5 decimal places for some UoM conversions, but S/4HANA enforces stricter precision rules depending on material type. Check table T006D for your conversion factor definitions - you may need to round or adjust precision before migration. Also, make sure your Migration Cockpit project is using the latest template version. SAP released updated material master templates in Note 2769355 that handle UoM conversions more robustly.
Look into your material type configuration differences between systems. S/4HANA has stricter validation rules for UoM assignments based on material type and industry sector. If you’re migrating materials across different material types or changing industry sectors during migration, the UoM validations might fail even with correct mapping. Run transaction OMSA in both systems and compare allowed UoM groups per material type.