ECC to S/4HANA Migration: The End-to-End Guide (2026)

An ECC to S/4HANA migration moves your ERP from SAP ECC 6.0 to SAP S/4HANA by one of three routes: a system conversion of the existing system, a new implementation, or a selective data transition. Whatever the route, the work follows the same arc: build the business case, assess readiness, pick the path and the deployment model, design and build, convert or load the data, validate, cut over, and run hypercare. ASUG's 2026 research puts the average go-live at about 1.4 years: 15.8 months for brownfield and 20.2 months for greenfield (diginomica, reporting ASUG research).

The calendar is the reason this is urgent. Mainstream maintenance for ECC ends at the end of 2027. Extended maintenance runs to the end of 2030 at a 2% premium (The Register). After that, ECC support comes only through the paid SAP ERP, private edition, transition option, for customers already in SAP's private cloud (SAP News Center).

This guide maps the whole move, and it treats every stage as ending in a sign-off decision, because that is where programs win or lose.

ECC to S/4HANA migration in one page

What changes. A HANA-only database, a new data model (Universal Journal, Business Partner, MATDOC), Fiori as the main UI, and a simplification list that documents every functional difference.

The three paths. SAP's transition documentation recognizes three approaches: system conversion, new implementation and selective data transition (SAPinsider).

The dates and duration. 2027, 2030 and 2033 (below, and in detail in ECC end of maintenance: what 2027, 2030 and 2033 really mean). Expect 15 to 20 months from kickoff to go-live for a single-instance program.

Where projects fail. In Horváth's survey of 200 SAP user companies, projects ran 30% longer than planned on average, and only 8% of completed migrations finished on schedule (CIO.com). The causes respondents named were scope growth, weak project management, underestimated testing and data migration phases, rework of concepts and processes, and slow decisions (Horváth).

1. Business caseSign-off: business case and budget approved
2. Readiness assessmentReadiness Check, SI-Check, custom code. Sign-off: readiness findings accepted
3. Path and deployment decisionSign-off: path and deployment decision record
4. Explore and fit-to-standardSign-off: delta backlog and test coverage map agreed
5. Build and convertSUM or Migration Cockpit. Sign-off: unit and string tests closed
6. ValidateSIT, UAT, reconciliation, mock cutovers. Sign-off: UAT sign-off form
7. Cutover and hypercareSign-off: go/no-go, then hypercare exit

Testing has its own guide, Testing an ECC to S/4HANA migration: a phase-by-phase plan. The benchmarks are collected in The S/4HANA migration by the numbers.

What actually changes from ECC to S/4HANA

The difference between S/4HANA and ECC is not a version number. S/4HANA is a separate product with its own data model, and every model change creates test scope. These are the changes that drive most of the effort in an ECC conversion.

Area	SAP ECC 6.0	SAP S/4HANA	What it means for testing
Database	Any certified database (Oracle, IBM Db2, SQL Server, SAP MaxDB, SAP HANA)	SAP HANA only	Performance baselines, native SQL in custom code, batch runtimes
Finance	Separate tables for GL, controlling, asset accounting and profitability	The Universal Journal (table ACDOCA) as the single line-item store	Pre/post balance reconciliation, period-end close
Customers and suppliers	Separate customer and vendor masters (XD01, XK01)	Business Partner as the single entry point (transaction BP), synchronized through Customer/Vendor Integration (CVI)	CVI completeness, BP roles, interfaces that create partners
Inventory	Material document header and item tables (MKPF, MSEG) plus aggregate tables	One material document table, MATDOC; old tables are served through compatibility views	Stock reports, custom code writing to old tables
User interface	SAP GUI	SAP Fiori launchpad, with SAP GUI still available for many transactions	Roles, catalogs, spaces and pages; app authorizations
Functional scope	Full ECC scope, including industry add-ons	Changes documented as simplification items; some ECC functions run only temporarily as compatibility scope	Every relevant simplification item becomes a test condition or an accepted risk

Compatibility scope has a deadline. For on-premise systems, SAP first set December 31, 2025 as the end of usage rights for most compatibility packs, then announced a final transition period to May 31, 2026 (SAP News; ASUG). That date has passed, so any compatibility pack still in use needs a replacement plan now. Three components, customer service (CS), transportation (LE-TRA) and production planning for process industries (PP-PI), have rights until the end of 2030. SAP Note 2269324 is the reference (SAP Community, SAP blog). If Readiness Check flags compatibility scope items, budget a follow-on replacement project with its own regression cycle.

The detail sits in the Simplification Item Catalog, which SAP's Conversion Guide for SAP S/4HANA 2025 lists as a mandatory companion document. Filter it to the items relevant to your system and give each an owner, a business impact, a custom code impact and a test approach. Our Simplification Item Test Impact Tracker uses exactly those columns.

Deadlines that drive the decision: 2027, 2030 and the transition option

• End of 2027. Mainstream maintenance for ECC stops. Extended maintenance is available to the end of 2030 at a 2% premium (The Register). ASUG notes that mainstream dates fall in 2025 or 2027 depending on your release (ASUG), so look up your enhancement package in the SAP Product Availability Matrix.
• December 31, 2030. Extended maintenance ends. To qualify for the transition option, systems must be on SAP ERP, private edition on SAP HANA by then (SAP News Center).
• 2031–2033. The transition option provides time-bound continuity, only with the separately priced max success plan (SAP News Center Germany, September 29, 2025).

The fine print: systems of at least 2 TB, purchase from 2028, and per SAP, not a maintenance extension for SAP ERP (SAPinsider). Customers who committed to SAP ERP, private edition by the end of 2025 switch in 2031 on equivalent terms; 2026 sign-ups pay a standard 20% uplift; later uplifts are undisclosed (SAP News Center). In early October 2026, an SAP-authored community blog said the offering has been extended through 2035 (SAP Community). Confirm terms against SAP Note 3591251 and with your account team before planning around it.

1. Dec 2025Promotion window closesNo-uplift commitment window ends; most compatibility pack rights expire
2. Mid-2026Latest start: live by end of 202718-month project bar ending at mainstream end
3. End 2027ECC mainstream maintenance endsExtended maintenance to end of 2030 at a 2% premium
4. Mid-2029Latest start: live by end of 203018-month project bar ending at extended maintenance end
5. Dec 31, 2030Extended maintenance endsDeadline to be on SAP ERP, private edition on HANA
6. 2031–2033Transition option coveragePaid subscription with max success plan; SAP reported an extension through 2035 in October 2026 (confirm terms)
7. Mid-2032Latest start: live by end of 203318-month project bar ending with original coverage

Choose your transition path: new implementation, system conversion or selective data transition

This decision sets your test strategy. A system conversion keeps configuration, custom code and history, so the test question is "does everything still work, and do the numbers still reconcile?" A new implementation builds a clean S/4HANA system and migrates the master data, open items, balances and history the target design needs (SAPinsider). There, the test question is "does the new design run the business?" A selective data transition keeps some configuration or history and redesigns the rest, adding a third question: did the selection rules move exactly the right data?

1. Do you need to keep ECC configuration and transaction history?Yes → go to question 2 · No → go to question 3
2. Is it a single instance with acceptable custom code quality?Yes → System conversion (ASUG 2026 average 15.8 months; test burden: regression, financial reconciliation, remediated code) · No → Selective data transition (no ASUG average; test burden: selection rules, cross-company reconciliation, repeated mock migrations)
3. Can the business accept SAP standard processes?Yes → New implementation on SAP Cloud ERP, public (ASUG 2026 greenfield average 20.2 months; test burden: fit-to-standard acceptance, data loads, release regression) · No → New implementation on SAP Cloud ERP Private or on-premise (20.2 months; test burden: end-to-end validation of a new build, extensions, data migration rehearsals)

Brownfield leads. In ASUG's 2025 research, 44% chose system conversion, 29% hybrid or selective and 26% greenfield (ASUG). ASUG's 2026 survey of 194 members found 47% brownfield and 30% greenfield (diginomica). ISG, counting "bluefield" broadly, reports 34% brownfield, 18% greenfield and about half in between (ITdaily).

Source: ASUG, 2025. Transition approach among ASUG members live on or moving to S/4HANA.

One trap: ISG found that 49% of organizations do little or no re-engineering (The Register). A lift-and-shift conversion moves every ECC workaround into S/4HANA, and each one still has to pass regression. Choose conversion because your processes are sound, not because it looks cheaper on a slide.

Choose your deployment and commercial model: on-premise, Cloud ERP Private (RISE) or Cloud ERP (GROW)

Path and deployment are separate decisions. RISE with SAP is a commercial cloud offering and doesn't determine whether the move underneath is brownfield, greenfield or selective (SAPinsider).

The names changed in 2025. SAP now markets S/4HANA Cloud Private Edition as SAP Cloud ERP Private and S/4HANA Cloud Public Edition as SAP Cloud ERP. SAP's own transition option material refers to the destination as "SAP Cloud ERP or SAP Cloud ERP Private" (SAP Community). Help Portal documentation still uses the product names, so expect both.

Option	Typical commercial vehicle	Paths available	Testing consequence
S/4HANA on-premise (2023, 2025 releases)	Perpetual license, you or a hoster run it	Conversion, new implementation, selective	You own every environment, upgrade and regression cycle
SAP Cloud ERP Private (S/4HANA Cloud Private Edition)	RISE with SAP subscription	Conversion (SAP publishes a separate Private Edition Conversion Guide), new implementation, selective	SAP runs infrastructure and technical operations; functional testing and sign-off stay with you
SAP Cloud ERP (S/4HANA Cloud Public Edition)	GROW with SAP or RISE subscription	New implementation is the standard path	Fit-to-standard acceptance up front, then regression for every SAP release

In ASUG's 2026 research, 42% of members used RISE with SAP private edition, 9% public edition and 9% GROW with SAP (diginomica).

A RISE contract changes who patches the operating system. It does not change who proves that order-to-cash still works. Responsibilities, line by line: RISE with SAP: what it includes, and why testing is still your job. Plan the post-go-live upgrade cadence now too: Life after go-live: S/4HANA upgrade cadence, clean core and regression.

Build the business case and budget

ASUG's 2026 research gives a useful split of where S/4HANA migration money goes (diginomica):

Source: diginomica, reporting ASUG research, 2026. Share of S/4HANA migration budget by category.

Only 35% of ASUG respondents said costs met expectations, and 3% came in under budget (diginomica). ISG's 2026 survey of 200 IT decision-makers found that six in ten S/4HANA migrations miss both their budget and their deadline (ITdaily).

Testing isn't one of ASUG's buckets. It's spread across SI fees, business time and tooling, which is why it gets underfunded. Estimate it bottom-up from the readiness output: in-scope processes, relevant simplification items, custom objects and interfaces, multiplied by test cycles (unit, SIT, UAT, regression, at least two mock cutovers). Our SAP Test Estimation Model is set up that way.

Assess readiness: Readiness Check, SI-Check, custom code and data

Readiness assessment turns opinions into a worklist. Each SAP instrument answers a different question.

Tool	What it tells you	Mandatory for conversion?	Sign-off artifact
SAP Readiness Check (report /SDF/RC_START_CHECK)	Relevant simplification items, high-level custom code analysis, add-on compatibility, sizing and more	No, but SAP highly recommends it	Findings accepted, owner per finding
Maintenance Planner	Whether your add-ons, active business functions and industry solutions have a valid conversion path; generates the stack file	Yes. SUM needs the stack file	Add-on and business function decisions logged
Simplification Item-Check (SI-Check)	Steps needed so the system can technically convert and processes run right after conversion, including consistency errors	Yes. SUM triggers it again during the conversion	SI-Check clean, or exemptions approved
Custom code checks and Custom Code Migration worklists	Which custom objects break, need adapting or can be retired	Required before conversion	Remediation scope and decommission list agreed

Sources: SAP Conversion Guide for SAP S/4HANA 2025; SAP, Getting Started With SAP S/4HANA 2025.

SAP Readiness Check runs against your production ECC system. A separate variant, SAP Readiness Check for SAP ERP usage and data profiling, profiles configuration and data volume to inform the path decision (SAP Community). For current capabilities, check SAP's Key Feature Overview.

The SI-Check and custom code worklists belong in the readiness phase, not the week before your first sandbox conversion. SAP recommends running them, with the Maintenance Planner, early in the project (SAP Help Portal).

Technical prerequisites. The system must be Unicode, and dual-stack systems must be split first (SAP Help Portal). Because SUM's database migration option includes Unicode conversion only for targets up to ECC 6.0 EHP 7, SAP recommends non-Unicode systems first upgrade to EHP 7 with DMO and Unicode migration (SAP Help Portal). For private edition conversions, SAP recommends backup storage of twice the HANA database size (SAP Help Portal).

Data readiness hides the long lead times. Readiness Check includes financial data quality and CVI analyses, and conversion success depends on consistent general ledger, asset accounting and material ledger data (Rapid-X). These findings often become pre-projects, and customer or vendor records that fail CVI synchronization block a conversion. Start cleanup months before the first sandbox run.

• Readiness Check results reviewed with process owners, not just Basis
• Every relevant simplification item logged with an owner, a business impact and a test approach
• Add-ons or business functions without a conversion path escalated as path-level risks
• Custom code usage analyzed so unused objects are retired, not remediated and tested
• CVI and financial data quality findings turned into dated pre-project tasks
• Findings accepted by the program lead and test lead before the path decision

Our S/4HANA Migration Readiness Checklist turns this list into a gate review. Part 2 continues with SAP Activate, the technical conversion, the data and integration workstreams, validation, cutover and hypercare.

Plan the project with SAP Activate

SAP Activate is SAP's delivery methodology for S/4HANA projects. It has six phases: Discover, Prepare, Explore, Realize, Deploy and Run. Quality gates (Q-gates) sit between the phases as checkpoints (SAP Community, SAP blog). In practice, Q-gate reviews happen in Prepare, Explore, Realize and Deploy, and SAP Cloud ALM can report on them (SAP Community). Treat each gate as a sign-off with named approvers and written evidence. A status meeting is not a gate.

Phase	Migration work	Quality evidence at the gate
Discover	Business case, Readiness Check, path and deployment decision	Readiness findings accepted; decision record signed
Prepare	Project setup, sandbox conversion or system provisioning, test strategy	Master test strategy approved; environment and transport plan agreed
Explore	Fit-to-standard workshops (new implementation) or delta design per simplification item (conversion)	Delta backlog plus a fit-to-standard to test coverage map
Realize	Configuration, code remediation, data loads, unit, string, SIT and UAT	SIT exit report; UAT sign-off form
Deploy	Mock cutovers, final regression, training, production cutover	Go/no-go checklist
Run	Hypercare, then steady state and upgrades	Hypercare exit criteria met

The technical migration step by step

System conversion: the sequence

The Conversion Guide for SAP S/4HANA 2025 sets the order. Run the Maintenance Planner before the Software Update Manager (SUM), because SUM needs the stack.xml file the Maintenance Planner generates. SUM then performs the database migration if one is needed, the software update and the data conversion. Every conversion from SAP ERP to S/4HANA has to use SUM 2.0. When the source runs on a database other than HANA, SUM's Database Migration Option (DMO) combines the update with the move to HANA (SAP PRESS).

1. Maintenance PlannerValidate add-ons and business functions; generate stack.xml
2. Pre-checksSI-Check, custom code worklists, CVI and finance consistency
3. SUM runDMO if not on HANA, software update, data conversion, SPDD
4. Post-SUM adjustmentSPAU, custom code fixes, role adjustments
5. Follow-on activitiesFinance migration to the Universal Journal and other application steps
6. Validate and repeatTest and reconcile, then convert development, QA and production in turn

Modification adjustment happens in two passes. SPDD handles ABAP Dictionary objects such as tables, data elements and domains, and skipping it causes data loss. SPAU runs after the new repository is activated and covers programs, function modules, screens and the remaining repository objects (SAP Learning). Both produce transports that carry the adjustments into later conversions. That makes the sandbox SPDD/SPAU work a deliverable, not a throwaway.

In finance, transaction FINS_MIG_STATUS is the main tool for running and monitoring the data migration into the Universal Journal, and it enforces the correct order of activities (SAP Community, SAP blog). It also lets you repeat checks and reschedule activities after errors (SAP Community). SAP Knowledge Base Article 2714344 lists the most frequent error messages. Read it before the first sandbox run, not after.

New implementation: the Migration Cockpit

For greenfield loads, the SAP S/4HANA Migration Cockpit runs through the Migrate Your Data Fiori app (app ID F3473). It can migrate data directly from certain SAP source systems or through staging tables (SAP Help Portal). On-premise, a third-party ETL tool can populate the staging tables, depending on your SAP HANA license (SAP Help Portal). As of S/4HANA Cloud Private Edition 2025 FPS1 and Public Edition CE2602, direct transfer from ECC can also write to staging tables, so data can be inspected and corrected before it is loaded (SAP Community, SAP blog). For testers, that extra step gives you a place to check the data before it reaches the target system.

Each migration object (cost centers, business partners, materials, open items, fixed assets) is test scope. It needs a load test, field-level validation and a reconciliation count in every mock.

Selective data transition

Selective projects usually combine a shell copy or a new build with tool-supported data transfer, most often delivered by SAP or specialist partners as a service. The technical sequence varies by tooling. The test question doesn't change: did the selection rules move exactly the company codes, years and objects agreed, and nothing else?

Data, integration, security and UX workstreams

Finance and data migration

Whatever the path, finance signs the data. Reconcile trial balances, open items, asset values and inventory values before and after every conversion or load, by company code and period. In a conversion, the Universal Journal merges ledgers that used to reconcile against each other, so differences that ECC tolerated now show up. Use the Data Migration Reconciliation Checklist, and agree tolerance thresholds with the controller before mock 1.

Business Partner and CVI

In a conversion, CVI synchronization is done in ECC before SUM runs. Test it in S/4HANA anyway. Check BP roles, number range alignment between customers, vendors and partners, and every interface or custom program that used to create customers or vendors directly. In a new implementation, business partners are often the largest and dirtiest load object. Give them their own data quality owner.

Integration

Many ECC customers route interfaces through SAP Process Orchestration. Mainstream maintenance for PO 7.5 ends December 31, 2027, optional extended maintenance runs through December 31, 2030, and after that only customer-specific maintenance is available, with no follow-on release (SAP Community, SAP blog). The move to SAP Integration Suite is a second migration running alongside the first. SAPinsider warns that a "Ready to migrate" status from the migration tooling does not guarantee a fully automated move (SAPinsider). Decide whether interfaces move before, with or after the S/4HANA cutover, and track each one in an interface inventory with a named partner-side tester.

Security and roles

Conversion keeps your roles, but not their behavior. Transactions are replaced, Fiori apps need catalog and authorization assignments, and the post-upgrade steps in transaction SU25 adjust authorization defaults. Test with real role combinations under named test user IDs, never with SAP_ALL, and include segregation-of-duties checks. The Security, Role and SoD Test Plan covers the cases.

User experience

In current releases, the Fiori launchpad is organized with spaces and pages assigned through roles. Design them per job role in Explore, then test navigation as part of UAT. A missing tile on day one causes as many tickets as a functional defect.

Validate before you sign off: testing, mock cutovers and reconciliation

Horváth's respondents listed underestimated testing and data migration phases among the main reasons their S/4HANA programs missed plan (Horváth). Validation has to be its own workstream from Prepare onward, with its own lead and budget. It shouldn't be a phase squeezed in between build and cutover.

Go/no-go evidence packSigned UAT, reconciliation sign-off, open defect list with accepted risks, cutover rehearsal results

User acceptanceProcess owners run end-to-end scenarios with production-like data and real roles

System integration testOrder-to-cash, procure-to-pay and record-to-report across interfaces, printouts and batch jobs

Data reconciliationBalances, open items, stock and counts before and after each mock

Regression and performanceUnchanged processes, critical reports and batch runtimes on HANA

Unit and string testsRemediated custom code, new configuration and each simplification item

The full phase-by-phase plan, including cycle counts, entry and exit criteria and who signs what, is in Testing an ECC to S/4HANA migration: a phase-by-phase plan. For the underlying work, see Test data for S/4HANA and what to automate first. The templates to start from are the ECC to S/4HANA Migration Test Plan and the SIT Cycle Plan.

Cutover, go-live and hypercare

Choose a downtime approach early

SUM offers three approaches for a system conversion: standard, downtime-optimized DMO and downtime-optimized conversion. SAP points out that these reduce only technical downtime (SAP Learning). Downtime-optimized conversion moves the finance migration, the MM-IM conversion and the VBFA and pricing table conversions into uptime processing (SAP Help Portal, SUM 2.0 SP25). Near-Zero Downtime Technology and, for RISE moves, the System Transition Workbench are further options (SAP Community, SAP blog). The test consequence: the more work moves into uptime, the more your reconciliation has to prove that changes made during uptime were captured correctly.

Business downtime also includes the work around the technical run: closing open documents, checks after conversion, finance's reconciliation and the go/no-go call. Rehearse all of it.

Mock cutovers and go/no-go

Run at least two full mock cutovers on production-sized data, and plan for a third. Time every step against the cutover runbook and log variances in a mock cutover rehearsal tracker. The final mock should finish inside the agreed window with reconciliation signed, or it isn't final.

• Last mock cutover completed within the downtime window, with fallback tested
• Reconciliation signed by finance for every in-scope company code
• UAT signed by each process owner; open defects classified and risk-accepted in writing
• Interfaces, output and batch schedule verified end to end
• Roles assigned and tested for go-live users; support model and hypercare rota staffed
• Rollback decision point and owner named in the runbook

Hypercare and exit

Set the length of hypercare by exit criteria, not the calendar. At minimum, it should cover the first month-end close. Typical exit criteria: no open priority 1 or 2 defects, ticket volume back to the agreed baseline, a clean period-end close, batch jobs within runtime targets, and knowledge transferred to the run organization. Log every incident in a hypercare triage log, and have the business and IT leads sign the exit together.

Realistic timeline and the most common failure modes

Source: diginomica, reporting ASUG research, 2026. Average time to go-live. Bars scaled to 24 months.

These are averages, not commitments. Six in ten migrations miss both budget and deadline (ITdaily, reporting ISG), and Horváth found projects ran 30% longer than planned on average (CIO.com). A 15.8-month plan with a 30% overrun ends up at about 20 months. Build that contingency into the deadline math in Figure 2. More benchmarks are in The S/4HANA migration by the numbers and on our statistics page.

Blockers found earlyAdd-ons without a conversion path, CVI failures, finance inconsistencies. Painful but fixable if Readiness Check ran on time.

The overrun zoneReconciliation breaks in the final mock, interface partners not ready, UAT testers unavailable, scope creep. Most overruns start here.

Routine remediationCustom code syntax findings, obsolete transactions, report variants. High volume but low risk when tracked.

Day-one irritantsMissing Fiori tiles, print layouts, user parameters. Low impact one at a time, but they flood the hypercare queue.

The pattern behind most of these failures is the same: decisions deferred until a test exposes them. Readiness findings with no owner, simplification items with no design decision and data cleanup started late all surface in the top-right quadrant. The Testing Risk Register keeps them visible at each Q-gate.

The bottom line

An ECC to S/4HANA migration combines a technical conversion with a data, integration and process change, under deadlines SAP has set. Pick the path based on the quality of your processes, not the price on a slide. Run the readiness tools before you sign contracts. Give validation its own lead, budget and evidence standard from Prepare onward. Every stage should end with a signed artifact that someone can defend. If your program can produce those artifacts on time, it can go live on time. Each week, our RISE Testing Playbook newsletter and The Sign-Off Table podcast take one of these sign-off decisions in more depth.

Frequently asked questions

What are the steps to migrate from ECC to S/4HANA?

Build the business case. Assess readiness with SAP Readiness Check, the SI-Check and custom code analysis. Choose a transition path (conversion, new implementation or selective) and a deployment model. Run Explore to design the deltas. Then convert with SUM or load data with the Migration Cockpit, validate through SIT, UAT, reconciliation and mock cutovers, cut over, and run hypercare to agreed exit criteria. SAP Activate structures this as Discover, Prepare, Explore, Realize, Deploy and Run, with quality gates between the phases.

What is the difference between ECC and S/4HANA?

S/4HANA runs only on SAP HANA and has a simplified data model. The Universal Journal (ACDOCA) replaces separate finance tables, Business Partner replaces separate customer and vendor masters, and MATDOC replaces the material document tables. Fiori is the main user interface. SAP documents every functional difference as a simplification item. Each relevant item needs a design decision, any custom code changes, and a test case or a documented accepted risk before go-live.

How long does an ECC to S/4HANA migration take?

ASUG's 2026 research puts the average at 15.8 months for brownfield conversions and 20.2 months for greenfield implementations, about 1.4 years overall. Plan for overruns: Horváth found projects run 30% longer than planned on average, and ISG reports that six in ten miss both budget and deadline. Multi-instance consolidations, selective transitions and programs with heavy custom code or data quality problems run longer. Size your timeline from the sandbox conversion results, not from benchmarks alone.

What are the prerequisites for an ECC to S/4HANA conversion?

The system must be Unicode, and dual-stack systems must be split first. You need a valid Maintenance Planner result for your add-ons, business functions and industry solutions, plus the stack.xml file that SUM requires. The SI-Check must pass or have approved exemptions. Customer and vendor records must be synchronized to Business Partners through CVI, and finance data (GL, asset accounting, material ledger) must be consistent. Custom code must be analyzed and remediated or retired. Readiness Check is not mandatory, but SAP highly recommends it.

Which tools are used for ECC to S/4HANA migration?

For assessment: SAP Readiness Check, the Maintenance Planner, the Simplification Item-Check and custom code analysis tools. For a system conversion: the Software Update Manager 2.0, with the Database Migration Option if you aren't on HANA, then SPDD and SPAU for modification adjustment and FINS_MIG_STATUS for the finance migration. For new implementations: the Migration Cockpit's Migrate Your Data app. SAP Cloud ALM supports project management, testing and quality gate reporting across all three paths.

Can we stay on ECC after 2027, and what happens in 2030?

Yes, with conditions. Mainstream maintenance ends at the end of 2027, and extended maintenance runs to the end of 2030 at a 2% premium. After 2030, the only SAP-provided continuity is the paid SAP ERP, private edition, transition option, which requires being on SAP ERP, private edition on HANA by December 31, 2030. SAP reported an extension of the offering in October 2026. Confirm current terms in SAP Note 3591251 and with your account team.

How do I migrate master data from ECC to S/4HANA?

In a system conversion, master data stays in place. Customers and vendors are converted to Business Partners through CVI before SUM runs, and finance data moves into the Universal Journal during the follow-on activities. In a new implementation, use the Migration Cockpit's Migrate Your Data app with direct transfer from ECC or staging tables. Either way, clean the data in ECC first, rehearse every load in each mock cutover, and have the data owners sign a reconciliation for each object.

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