SAP MODERNIZATION SERIES | BOOK 2
The SAP Migration
Minefield
Data quality failures, interface fragmentation, and the cost and schedule crises that derail SAP ECC to S/4HANA programs.
Introduction
Why SAP Migrations Struggle
The decision to migrate from SAP ECC to SAP S/4HANA is no longer optional for most enterprises — it is a strategic imperative driven by SAP’s 2027 maintenance deadline. But making that decision and executing it successfully are two very different things. The gap between the two is where organizations consistently lose time, money, and competitive momentum.
This e-book examines three of the most significant challenges that SAP IT organizations encounter during the ECC-to-S/4HANA journey: the data quality crisis that derails migration programs, the multi-interface fragmentation that erodes user productivity, and the cost and schedule overruns that push migrations far beyond their original parameters. Each is well documented. Each is chronically underestimated. And each is addressable — with the right strategy and the right tools.
Challenge 1:
Data Quality — The Silent Migration Killer
Ask any experienced SAP migration consultant what most consistently derails programs, and the answer is almost always the same: the data. Not the technical architecture, not the configuration complexity — the data. Specifically, the gap between what organizations think their ECC data looks like and what it actually looks like when subjected to the scrutiny that an S/4HANA migration requires.
ECC systems have been accumulating data for an average of 15-20 years at large enterprises. Over that time, data entry practices have varied enormously. Duplicates proliferate — particularly in business partner data where customer and vendor masters were managed separately. Custom Z-fields create data structures with no direct S/4HANA equivalent. And fields that were optional in ECC may be mandatory in S/4HANA’s tighter data model.
Most Common SAP ECC Data Quality Issues
- Duplicate business partner records with inconsistent attributes across duplicates
- Materials master data with missing MRP parameters, incorrect units of measure, or outdated classifications
- Incomplete or incorrect vendor bank account data, causing payment failures post-migration
- Cost center hierarchies that no longer reflect current organizational structure
- Non-standard field values that were tolerated in ECC but violate S/4HANA validation rules
- Custom Z-field data with no direct equivalent in the S/4HANA data model
0
%
of organizations report data quality issues significantly impact business operations — yet only 17% have invested in formal data quality programs. (Experian Data Quality Research, 2024)
The Business Partner Consolidation Problem
One of the most consistently cited data migration challenges is Business Partner (BP) consolidation. In ECC, customer and vendor records are managed in separate data objects. In S/4HANA, both consolidate into the unified Business Partner object. Organizations with separate customer and vendor records for the same real-world entity must identify overlapping records, merge their attributes, and create a unified BP with correct role assignments — a process that is far more complex in practice than it sounds. Research shows 60-80% of ECC-to-S/4HANA programs cite BP consolidation as a significant source of remediation effort and timeline risk.
4-6 wks
Average timeline extension caused by each additional mock load failure cycle, with proportional cost increases. Three or more failed cycles is not uncommon.
(IDC, SAP Migration Cost Analysis, 2024)The Mock Load Cycle: Where Reality Hits
The mock load — a simulation of the actual migration cutover — is where data quality issues become undeniable. First-pass yields of 70-80% are common in organizations that haven’t invested in pre-migration remediation, meaning 20-30% of objects fail outright. Each failed object requires diagnosis, business owner engagement, remediation, and re-validation. Across hundreds of thousands of records, this accumulation of exceptions is enormous — and expensive.
Crucially, migrating to S/4HANA doesn’t solve data quality problems — it makes them more visible. S/4HANA’s tighter integration means that a quality issue in one data domain cascades more rapidly into others than it did in ECC. Organizations that carry dirty data into S/4HANA experience immediate post-go-live problems: failed transactions, incorrect reports, and the gradual re-accumulation of the same quality issues that caused problems before.
“We thought our data was a minor cleanup task. By the time we reached our first mock load, we realized it was the largest single work stream on the entire program.”
— VP of IT, Global Manufacturing Company
(Forrester Customer Interview, 2024)
Challenge 2:
The Multi-Interface Maze
One of the most practically disruptive aspects of the ECC-to-S/4HANA transition is something that rarely gets the attention it deserves in migration planning: the fragmentation of user interfaces. During the transition period — which often lasts 18 months to several years — business users must navigate between multiple SAP interface environments, sometimes multiple times in the same working day.
Three Interfaces, Three Mental Models
SAP GUI — the original client-server application familiar to power users — remains available throughout the transition but is increasingly supplemented or replaced by Fiori’s modern, role-based web UI. SAP Web GUI (GUI for HTML) adds a third paradigm: a browser-based rendering of SAP GUI transactions, commonly used to provide ECC access during the parallel operations period. Each interface has a different navigation structure, different interaction model, and different level of process guidance.
3x
Users switching between three or more interface paradigms in a single workday experience up to 3x more errors and take 40% longer to complete routine tasks.
(Human Factors in Computing Research, 2023)40%
of organizations running ECC and S/4HANA in parallel report a significant productivity decline in the first 6 months, primarily attributed to interface fragmentation and change management gaps.
(Forrester Research, 2024)The Productivity and Governance Impact
The productivity impact of this context-switching is well documented in human factors research. Cognitive load increases when users maintain separate mental models for parallel workflows. Error rates increase because the cues experienced users rely on differ between interfaces. Training costs multiply because SAP GUI proficiency no longer prepares users for Fiori, and vice versa.
Multi-interface fragmentation also creates data governance risk. When the same process — vendor onboarding, customer change request, materials master update — is executed through different interfaces by different users or teams, the results are inconsistent. Fiori applications may enforce stricter validation rules than legacy SAP GUI transactions. Users who discover that one interface bypasses controls they find burdensome will use it — generating audit trail gaps and data quality problems that undermine the entire migration program’s data integrity goals.
“In the first three months after our partial go-live, support ticket volume doubled — and most of it was interface confusion, not system errors.”
— SAP Center of Excellence Lead, Financial Services Company (Precisely Customer Insights, 2024)
Challenge 3:
Cost and Schedule Overruns
The research on SAP S/4HANA migration outcomes is clear and consistent: most programs take longer and cost more than originally planned. This is not primarily a reflection of poor project management. It is a structural feature of programs that are, in almost every case, significantly more complex than initial planning assumptions captured.
Root Cause #1:
Data Migration Underestimation
The data quality challenge described in Chapter 1 is also the single most common driver of cost and schedule overruns. System integrators, under competitive pressure to propose aggressive timelines, often scope data migration as a relatively contained technical workstream — extract, transform, load. The business-led effort for actual data remediation — human review, exception handling, approval workflows, multiple rounds of correction — is consistently under scoped because it is harder to estimate and less familiar to the technical consultants building the project plan.
When the gap between planning assumptions and reality becomes visible during the mock load cycle, programs face a binary choice: extend the timeline for additional remediation cycles, or accept lower data quality and plan to clean up issues post-go-live. Neither option is cheap — and neither was in the original budget.
53%
of SAP S/4HANA implementations exceed their original budget. Average cost overrun: 24% above estimate. 58% also exceed their original timeline by an average of 6.4 months.
(Panorama Consulting, ERP Report 2024)68%
of SAP ECC customers discover they have more custom code than initially realized once formal migration assessment begins. The median large enterprise has 500+ Z-transactions requiring evaluation.
(SAP Research, 2024)Root Cause #2:
Custom Code Complexity
The second most commonly cited overrun driver is custom code. Most ECC environments carry hundreds to thousands of Z-transactions, custom reports, and bespoke enhancements that SAP’s standard migration tools (the Migration Cockpit) simply don’t handle. Each custom object must either be re-implemented in S/4HANA, replaced by standard functionality, or retired — none of which is fast or straightforward. The median large enterprise has over 500 custom Z-transactions requiring evaluation, and 68% of ECC customers discover they have more custom code than they initially realized.
Root Cause #3:
Scope Creep and Consultant Continuity
S/4HANA migration programs create rare organizational focus on SAP processes — which consistently surfaces years of accumulated process improvement requests from business stakeholders. Each additional requirement extends scope, adds testing cycles, and increases the change management burden. Without disciplined scope governance, these individually reasonable requests combine into a significant overrun driver.
Consultant continuity adds further risk. Experienced SAP migration specialists are in extreme demand as the wave of ECC customers races toward 2027. Key consultant departures generate knowledge transfer costs — research estimates each key transition costs an average of $250,000 when accounting for ramp-up time and corrective work on decisions made without full program context.
Read Book 3: From Complexity to Confidence with Precisely Automate
Conclusion:
These Challenges Are Addressable
The challenges described in this e-book are real, significant, and not going away. But they are also well understood — and organizations that approach them with rigorous pre-emptive investment rather than reactive remediation consistently achieve dramatically better outcomes. The pattern is clear: systematic data profiling before the first mock load, governed tooling that provides a consistent user experience across SAP environments, honest scope governance, and realistic resource planning all reduce both overrun magnitude and program risk.
Book 3 in this series examines exactly how Precisely and Precisely Automate address each of these challenges — providing the data quality, automation, and user experience capabilities that help organizations execute SAP migrations more successfully and build the operational foundation for long-term S/4HANA performance.
Sources & References
Industry Research
- Panorama Consulting Group. (2024). ERP Report 2024. https://www.panorama-consulting.com/resource-center/erp-reports/
- IDC. (2024). SAP Migration Cost Analysis: The True Cost of Data Quality Failures. https://www.idc.com
- Forrester Research. (2024). ERP Transition Productivity Study: Managing the Human Impact of SAP Migrations.
- Forrester Research. (2024). SAP Modernization Insights: Customer Interviews and Case Studies.
- Experian Data Quality. (2024). Global Data Management Benchmark Report. https://www.experian.com/business/decisions/data-quality
- KPMG. (2024). SAP S/4HANA Transformation Research: Post-Go-Live User Adoption. https://kpmg.com
- Gartner. (2024). SAP Migration Practice Research: Business Partner Consolidation and Data Quality.
- Human Factors in Computing Systems (ACM CHI). (2023). Cognitive Load and Interface Context-Switching in Enterprise Applications.
- Deloitte. (2023). SAP Practice Research: Consultant Continuity and Knowledge Transfer Risk.
SAP & Precisely
- SAP SE. (2024). Custom Code Modernization for SAP S/4HANA. https://help.sap.com/docs/SAP_S4HANA/custom-code
- Precisely. (2024). SAP Modernization Positioning Guide V3. Precisely Internal Document.
- Precisely. (2024). CXO Challenges in SAP ECC to SAP S/4HANA Modernization V4. Precisely Internal Document.
- Precisely. (2024). Precisely Automate Top-Line Messaging Framework – Draft V2. Precisely Internal Document.