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“Every success story is a tale of constant adaption, revision and change.” – Richard Branson

In line with the very same philosophy, SAP rebuilt SAP ECC from the ground up to create SAP S/4HANA in 2015 to take advantage of SAP HANA's performance and data analytics capabilities.

To start with a simple SAP ECC to SAP S/4HANA conversion, the foremost thing to understand is the basic difference between the two.

Below are few major differences between SAP ECC and SAP S/4HANA:

Intelligent Technologies - All – embedded machine learning, advanced analytics, and digital assistants with voice recognition
Database Disk-based databases SAP HANA in-memory database; real-time Online Analytical Processing and Online Transaction Processing from one data model
Data Model Complex data model – redundant tables for analysis means blocking and maintenance issues Simple data model – combined analytics and transactions, reduced reconciliation, blocking, and maintenance
Business Processes Traditional processes constrained by the legacy database Intelligent processes powered by new technology and SAP HANA
User Interface Legacy graphical user interface (SAP GUI) SAP Fiori – modern, customizable, and intuitive User Interface
Deployment On premise Complete choice of on premise, cloud, or hybrid with consistent code line, data model and interface
Road map Supported until 2027 Supported until 2040

(Data Source: SAP)

System Conversion in short is typically the fastest option, an approach that converts any SAP ECC 6.x system running on any database to SAP S/4HANA, preserving your existing configuration, customizations, and historical data. This approach allows a rapid technical conversion, adding innovations gradually for users.

The major teams involved in a conversion project are the Technology Team (responsible for executing the Software Update Manager(SUM) tool in all the platforms(Sandbox, Development, Quality, Dry and Production)) ; Functional Team (responsible for pre-check for Software Update Manager compatibility, Functional factory, Migration to new Finance Tables, Credit Management and Material Ledger activation, involving different Lines of Business) ; Security Team (adjustment of roles for new Fiori applications) ; the Advanced Business Application Programming (ABAP) Team (responsible for the custom code adaption, SAP S/4HANA code remediation etc.) and a Fiori Team (responsible for setting up the Fiori Launchpad and Launchpad designer).

To begin with a conversion project, we first need to discuss and decide on the data cleansing. This includes master data as well as transactional data cleansing (Cleansing historical data) based upon the customers’ statutory requirements. The data cleansing helps in reducing the database size to be converted proving beneficial to the technology team for a smooth conversion.

(Image Source: SAP)

Starting with the Prepare phase, the base document to start with the conversion is the Readiness Check Report: (Transaction SE38 - execute /SDF/RC_START_CHECK)

Readiness Check is a high level analysis to get a Results  Dashboard and also download to a Results Document with details of Active Business Functions, Add-On Compatibility,  Custom Code Analysis, Recommended Fiori Apps, SAP S/4HANA Sizing, Simplification Items, Business Process Analytics and Data Volume Management.

The main elements that need to be analyzed from a functional point of view are - Active Business Functions, Add-On Compatibility and Simplification Items.

Active Business Functions – The active business functions, enable us to use specific new features and enhancements for our various business processes.

In SAP S/4HANA business functions can have the following status: 'always_on' , 'customer_switchable' , and 'always_off' . This results in the following behavior during the system conversion:

  • If a business function was switched on in the start release system, but defined as 'always_off' in SAP S/4HANA, on-premise edition, then a system conversion is not yet possible with this release at the current point in time.

  • If a business function was switched off in the start release system, but defined as 'always_on' in the target release, then the business function will be automatically activated during the conversion.

(Data Source – SAP Note 2240360 and 2240359 )

Add-On Compatibility – The check analyzes how many add-ons are installed in the system, with the help of a Maintenance Planner whether they are compatible with SAP HANA.

The Add-Ons existing on a customer’s SAP ECC system that shall be part of the target SAP S/4HANA release must be supported in order to permit the system conversion/upgrade process to go through.

The Maintenance Planner is a solution hosted by SAP that helps you plan and maintain systems in your landscape. The Maintenance Planner also helps the customer get a view on the compatibility status of the Add-Ons on his/her SAP ECC system before system conversion/upgrade to SAP S/4HANA.

Please refer https://blogs.sap.com/2021/03/15/handling-add-ons-during-a-system-conversion-to-sap-s-4hana/ for detailed description on handling Add-ons during system conversion.

Simplification Items – By executing the above mentioned report you can get a list of Simplification Items that are relevant to the specific customer database and must be looked into before converting the SAP ECC system to SAP S/4HANA.

Below is how the Simplification Items List, post execution of the Readiness Check Report in SE38 looks like:

(Image Source: SAP)

The column 'Relevance' describes the relevance of the item (relevant/ not relevant/ relevance cannot be determined(execute the check manually)).

The second column talks about the consistency of the item (warning/error/resolved/inconsistent). The Items with errors and warnings are the ones that need to be looked into and resolved before moving for conversion. There is also an option for exemption of the simplification items. This can be applied to the items that can be covered post conversion and would not impact the Software Update Manager run in any ways.

Each Simplification Item has a reference SAP Note that explains how to proceed in resolving the specific item. Referring to the corresponding notes, a consultant can easily proceed with the resolution of the open simplification items.

The Conversion works in three phases at a high level:

Pre-Conversion --- Software Update Manager (executed by technology team) --- Post-Conversion 

Pre-Conversion and Detailed Assessments:

The resolution of the Simplification Items is a pre-conversion activity. From Logistics side, most of the activities are Pre-Conversion, whereas for Finance, we have a lot of involvement during Post-Conversion as well. During this phase we conduct Detailed Assessment Sessions with the customers, introducing them to the possible changes that might directly or indirectly impact the business process once the system is converted.

Fit-Gap Analysis:

This is an important milestone, where the changes and their business impact is discussed in detail with the customers.  There are certain optional changes as well that are a part of conversion and should be explained to the customer in the As-Is and To-Be format in order to provide an opportunity to the customer to decide whether they want to proceed with the To-Be process or if they are okay with the current process and want to perform it As-Is. Another important decision that need to be discussed and taken is on the Fiori apps. Post conversion there are certain FI transactions that would become completely obsolete and would be replaced by Fiori. Along with the mandatory applications, customers also have a choice to implement Fiori apps for transactions that are still supported in SAP S/4HANA as well. These discussions can be conducted during the Fit-Gap Analysis sessions.

Software Upgrade Manager (SUM):

Post Completion of the identification and resolution of the Simplification Items, Basis team executes the  SUM (Software Upgrade Manager) tool - a multi-purpose tool that supports various processes, such as performing a release upgrade, installing enhancement packages, applying Support Package Stacks, installing add-ons, or updating single components on SAP NetWeaver.


Following the Software Update Manager Conversion, next comes the turn of the post-conversion activities. These include the manual data migration, custom Code adaptions, any Workflows, Reports, Interface, Conversion, Enhancements and Forms (WRICEF) implementations that are required as part of the customer requirements and the system landscape.

Along with the above, the consultants are also required to prepare configuration document/run book that can further be used as a guide to understand the major configuration changes that have been conducted as part of the conversion.

Once we are done with the Post-Conversion Activities we proceed with the testing. This process is applicable for all the landscapes (Sandbox, Development and Quality). In Sandbox, we perform a smoke test, in order to test the basic transactions and functionalities. Similarly, in Development, we perform a round of unit testing. Once the Quality system is converted, System Integration Testing(SIT) and User Acceptance Testing(UAT) is conducted from the customer’s end (with the support of SAP).

Cutover Plan:

Post the System Integration Testing(SIT) and User Acceptance Testing(UAT) Sign-off, we start with the cutover planning. This includes a planned timeline for all the relevant actions to be performed in the dry run and the Production system to implement the final SAP ECC to SAP S/4HANA Conversion. The cutover plan includes the responsible Lines of Business's points of contact and their activities timed and planned in order to have a smooth and successful conversion.

Thus, to conclude, a successful conversion to SAP S/4HANA can be conducted if the above mentioned key points are considered and well looked into.

For more information on topics relevant to SAP ECC to SAP S/4HANA Conversion please do refer the below:




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