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Migrating from SAP WM to Embedded EWM: Step-by-Step Migration Guide

Migrating from SAP WM to Embedded EWM is not merely a technical system upgrade; it is a strategic migration project that requires the redesign of warehouse processes. Although SAP’s Migration Cockpit supports this transition in a structured manner with 34 separate migration objects, the most common errors experienced stem from gaps in cross-functional preparation. In this guide, we walk through migration phases, frequent mistakes, customizing transfer strategies, and cutover management step by step.

Migration Preparation: Understanding Your WM System

Before starting a WM-EWM migration project, the existing system must be analyzed in depth. Skipping or rushing through this phase leads to serious time and cost losses in subsequent stages.

Key areas to examine:

  • Warehouse Number structure: Number of warehouses, storage type, storage section, and bin configurations
  • Transfer Order volume: Monthly/weekly average number of TOs and peak periods
  • Custom developments (Z code): Custom reports, user-exits, and BAdI usage written on WM
  • Integration points: WMS, MES, barcode scanner systems communicating with WM
  • RF/barcode terminal usage: Number of existing terminals, transaction codes in use

As MDP Group, identifying Z codes and determining their standard equivalents in EWM during the analysis phase is of critical importance. Every Z code either needs to be migrated to EWM standard or redeveloped.

Choosing the Migration Approach: Brownfield or Greenfield?

Two fundamental approaches exist when migrating from WM to EWM:

Greenfield (Fresh Installation): S/4HANA EWM is configured completely from scratch. WM customizing is not transferred; processes are redesigned based on EWM best practices. Produces a cleaner system in the long run, but requires more project time and resources.

Brownfield (Conversion): The existing ECC/WM system is converted to S/4HANA. Some WM customizing can be automatically migrated, but EWM-specific new configurations must still be completed manually. In particular, storage type → warehouse process type and transfer order → warehouse task conversions require careful attention. When deciding which approach is right, correctly analyzing the structural differences between WM and EWM will clarify your approach selection.

SAP Migration Cockpit with 34 Migration Objects

SAP supports the WM-to-EWM transition through Migration Cockpit (transaction LTMC/LTMOM). This tool manages structured data transfer operations across 34 different migration objects.

The most critical migration objects:

Static Master Data:

  • Warehouse Structure: Warehouse number, storage type, storage section, storage bin definitions
  • Warehouse Product: EWM-specific fields for each material; putaway/stock removal strategies, handling unit type
  • Storage Bin Master: Bin attributes, maximum weight/volume, accessibility status

Transactional Data:

  • Open Transfer Orders: WM transfer orders still open at cutover time; these must be converted to EWM warehouse tasks
  • Stock Data: Bin-level stock information, including batch and serial number data
  • Open Inbound/Outbound Deliveries: Transfer of open delivery documents to EWM

Important note: Migration Cockpit allows you to load data via templates (Excel/CSV), but data quality is critically important. Data cleansing must be performed before loading.

Customizing Transfer Strategy

WM customizing does not map one-to-one to EWM. Due to structural differences, the following conversions must be performed manually:

WM Movement Type → EWM Warehouse Process Type
Movement types in WM (201, 261, 311, etc.) correspond to warehouse process types in EWM. However, the workflow logic differs; in EWM, outbound delivery order, inbound delivery order, and warehouse task are separate objects.

WM Storage Type → EWM Storage Type + Storage Section + Storage Bin Type
EWM’s warehouse structure uses a more granular hierarchy than WM. When migrating your existing WM warehouse structure to EWM, you need to model this structure correctly.

WM Putaway/Stock Removal Strategy → EWM Putaway/Stock Removal Strategy
Strategy codes in WM are configured in EWM through search sequence and storage section indicators.

Common Migration Errors and Preventive Measures

Error 1: Warehouse Product Master missing or incorrectly populated
A Warehouse Product Master (WPM) must be created for every material in EWM. Without WPM, putaway and stock removal strategies do not function. In WM, this information is held on the Material Master WM view, whereas in EWM it has been moved to a separate object.

Preventive measure: Before migration, prepare WPM data for all active materials and load it into the Migration Cockpit template.

Error 2: Ignoring open Transfer Orders
Transfer Orders that remain open in WM at cutover time do not automatically migrate to EWM. These documents must either be manually completed or cancelled and recreated in EWM.

Preventive measure: Define a freeze window before cutover; do not proceed to cutover without zeroing out transfer orders.

Error 3: Leaving RF/barcode terminal configuration until the last minute
EWM’s RF Framework differs from WM transaction codes. Terminals need to be reconfigured for new EWM transaction flows, tested, and users trained.

Preventive measure: Start RF/terminal tests at least 6 weeks in advance. Conduct full user testing at a pilot warehouse.

Error 4: Skipping stock reconciliation
After migration, verifying alignment between WM and EWM stocks is mandatory. Go-live should not proceed without running bin-level stock comparison reports.

Cutover Management: Migration Day Plan

A successful cutover is the product of preparation that starts weeks in advance. Below you can see a recommended cutover plan:

Cutover -2 Weeks:

  • Final data cleansing is completed
  • Migration Cockpit test loads (at least 3 full tests) are completed
  • Cutover schedule planner (runbook) is prepared and approved

Cutover -48 Hours:

  • New transaction entry in WM is stopped (freeze)
  • Open transfer orders are completed or cancelled
  • Final stock count is performed and IM/WM reconciliation is confirmed

Cutover Day:

  • Master data loading via Migration Cockpit: warehouse structure, storage bins, warehouse products
  • Stock data loading (bin-level)
  • Running stock reconciliation reports
  • Smoke test: sample inbound and outbound transactions on EWM
  • Final check of RF terminals
  • Go/No-go decision meeting

First 48 Hours After Go-Live:

  • Intensive monitoring: warehouse task error logs, completion rates
  • Key users on-site; key user support active
  • Daily stock reconciliation checks

Finalize Deployment Model Before Migration

Before starting migration, decide whether to use Embedded or Decentralized EWM, considering the automation scenarios EWM supports. The choice between these two models shapes your entire migration plan.

Frequently Asked Questions (FAQ)

Is using Migration Cockpit mandatory, or can it be done with manual configuration?

Migration Cockpit is not mandatory; however, managing 34 migration objects through templates reduces the likelihood of errors and provides traceability. Using Migration Cockpit is strongly recommended especially for loading stock and bin data.

Can WM Z codes be automatically migrated to EWM?

No. Custom ABAP developments on WM cannot be directly migrated to EWM. The standard equivalent of each Z code in EWM must be analyzed; if no standard equivalent exists, it must be redeveloped using EWM BAdIs or Business Add-Ins.

How long does migration take?

A medium-complexity WM-EWM migration project (2–5 warehouses, limited Z code) typically takes 4–6 months. For high-volume, multi-site projects with extensive custom developments, this duration can extend to 9–12 months.

Conclusion: Preparation Quality Determines Migration Success

Migrating from SAP WM to Embedded EWM is a multi-phase project requiring proper planning, comprehensive data preparation, and testing discipline. Migration Cockpit and the 34 migration objects provide a powerful infrastructure; however, an experienced team is essential for correct use of this infrastructure.

As MDP Group, we are ready to support your project through the preparation, design, and cutover phases, drawing on our experience in WM-EWM migration projects.

References

SAP Help Portal – Extended Warehouse Management for S/4HANA
MDP Group – SAP WM or EWM? Choosing the Right Warehouse Solution
MDP Group – Embedded EWM vs Decentralized EWM


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