# SAP S/4HANA upgrade steps: a runbook for manufacturers > Source: https://netray.co/erp-help/sap-s4hana-upgrade-steps-conversion-runbook > Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems. > Section: ERP Help ## Short answer An S/4HANA move runs in phases: assess with the readiness check and simplification items, clean up and adapt custom code, plan the stack in Maintenance Planner, run the technical conversion or upgrade with SUM in a sandbox, test business processes, rehearse the cutover and go live. Most of the effort is in custom code, data and testing, not the tool. ## Kind how-to ## System sap ## Erp SAP ECC to S/4HANA ## Module Basis / Migration and Upgrade ## Query sap s4 hana upgrade steps ## Alternate Queries - sap s/4 hana upgrade steps - sap s4 hana upgrade guide - ecc to s/4hana conversion steps SUM ## Applies To SAP ECC 6.0 to S/4HANA system conversion, and upgrades between S/4HANA releases on-premise ## Steps ### The upgrade runbook **Items:** Decide the path: system conversion (brownfield) keeps your data and customizing, new implementation (greenfield) starts clean, and selective data transition sits between. An upgrade from one S/4HANA release to the next uses the same SUM tool with a smaller scope. Run the SAP Readiness Check for the source system and the Simplification Item Check. These list the simplification items that apply to you, such as business partner, material number length, inventory and finance changes. Analyse custom code with the ABAP Test Cockpit (ATC) checks for S/4HANA and the custom code migration tooling. Remove unused code first with usage statistics, then fix what remains. Plan the target in SAP Maintenance Planner: define the target release, add-ons and languages, and generate the stack file (stack XML) that SUM consumes. Confirm hardware, HANA database version and operating system. Prepare a sandbox copy of production. Run pre-conversion activities such as customer-vendor integration to business partner, data cleanup, and reduction of data volume through archiving. Run SUM (Software Update Manager) with DMO, including the database migration to HANA when moving from another database. Resolve the findings and re-run on a fresh copy until the downtime is acceptable. Execute post-conversion tasks, adapt Fiori and authorizations, then run test cycles on business processes and interfaces. Rehearse cutover, cut over production, and monitor the hypercare period. ## Sections ### What drives effort **Body:** The technical conversion is a small part of the project. The larger work is the business and data side: converting customers and vendors to business partners, changes to inventory management (material document tables), the universal journal in finance, material ledger activation for valuation, and the new data model for MRP. Each of these is a simplification item with pre- and post-conversion tasks. Custom code is the typical schedule risk. Manufacturers often carry years of enhancements into pricing, production confirmations and quality processes. Use ATC findings to separate what must be fixed, what can be retired and what the new standard replaces. ### Manufacturing specifics to check early **Body:** Check the production planning functions your plants use: MRP Live replaces classic MRP run behaviour, so procedures and planning reports change. Review quality management inspection types, subcontracting and any special procurement. Shop floor interfaces to MES, scanners and label printers often depend on 18-character material numbers or old tables, so test them explicitly. Regulated or defense manufacturers should plan validation documentation in parallel, because change control and traceability evidence is required for the conversion itself. ### Dual maintenance, testing and cutover **Body:** Most projects freeze changes to the source system during the final phase, or run dual maintenance with a defined transport process until go-live. Decide this early; undisciplined changes in production during a long project are a common cause of late defects. Test in layers: technical (jobs, interfaces, authorizations), functional (order to cash, procure to pay, plan to produce, record to report) and performance (MRP runs, month-end close). Automate regression tests where possible. For cutover, rehearse at least twice, time each step, and agree a rollback point. **Code:** - Tools: SAP Readiness Check, Simplification Item Check, ATC (S/4HANA readiness checks), Maintenance Planner, SUM (with DMO) - Typical sequence: Assess > Prepare > Convert in sandbox > Test > Rehearse cutover > Go live > Hypercare ### Timeline and support dates **Body:** SAP has announced end of mainstream maintenance for ECC 6.0 at the end of 2027, with an extended option to 2030 at extra cost. Check SAP's current published dates before building a business case. Typical project durations are measured in many months to a couple of years depending on landscape size, so the plan should start from the date you must be live and work backward. ## Pitfalls - Starting with the tool and discovering simplification items late. - Carrying all custom code over without usage analysis. - Testing only transactions and not integrations to MES, EDI and label printers. - Running a single rehearsal and trusting the downtime estimate. - Ignoring data quality before the business partner conversion. ## Ai Angle Several upgrade tasks are reading tasks: finding which custom objects touch changed tables, which reports use old stock tables, and which interfaces hard-code field lengths. A grounded assistant working against your own system and code can produce these lists and suggest fixes for review. For regulated manufacturers the model can run on-prem so source code and data stay in-house. The upgrade itself remains an SAP Basis and functional project. ## Faq ### What are the main steps in an SAP S/4HANA upgrade? **Answer:** Assess with the readiness check, clean up and adapt custom code, plan the target in Maintenance Planner, run the conversion with SUM in a sandbox, test the business processes, rehearse cutover and go live. Data and custom code drive most of the effort. ### What is SUM in SAP? **Answer:** Software Update Manager is the tool that performs upgrades and system conversions. With the Database Migration Option it can also migrate the database to HANA in the same run. It consumes the stack file generated by Maintenance Planner. ### Is an upgrade from ECC to S/4HANA a normal upgrade? **Answer:** No, it is a system conversion with data model changes, such as business partner and the universal journal, so it needs business preparation as well as a technical run. Moving between S/4HANA releases is closer to a normal upgrade. ### How long does an S/4HANA conversion take? **Answer:** It depends on landscape size, custom code and data quality. Small, clean systems may take months; large manufacturing landscapes with many interfaces commonly take a year or more. Use a sandbox run to calibrate before committing a date. ## Search terms sap s4 hana upgrade steps, sap s/4hana upgrade guide, ecc to s/4hana conversion, sap sum software update manager, sap readiness check, sap maintenance planner, s/4hana brownfield conversion steps, s/4hana custom code migration --- Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json