SAP ECC to S/4HANA Migration: Choosing Your Path While Getting Ready for AI

"Start implementing Joule early, ideally in parallel with the migration. Many embedded AI scenarios only become fully available post-transformation."

— Philipp Herzig, CTO & Chief AI Officer, SAP

SAP ECC mainstream support ends on December 31, 2027 — and with a typical migration taking 12 to 24 months, the window to migrate on your own terms is closing now. But the migration path you choose will determine not just whether you make the deadline, but whether you arrive at S/4HANA positioned to use AI or scrambling to catch up. With 60% of companies currently skipping SAP Joule AI integration during their S/4HANA transitions, there is a widening gap between those who treat this as a technical lift and those who treat it as a strategic reset.

Why the ECC Clock Is Running Out Faster Than You Think

SAP's mainstream maintenance for ECC — covering security patches, legal updates, and regulatory compliance — ends December 31, 2027. Extended maintenance is available until 2030, but at significantly higher licensing costs and with a reduced scope of updates. For most organizations, the practical deadline is not 2027 or 2030 — it is now.

A typical S/4HANA migration takes 12 to 24 months from scoping to go-live, depending on system complexity, the number of custom developments, and data quality. That means an organization starting today is targeting a mid-to-late 2027 go-live at the earliest — cutting it uncomfortably close to the support deadline. Organizations that delay into 2026 are looking at potential timeline overlaps that force either rushed execution or a period on extended maintenance. And consulting costs are rising: implementation partner fees are projected to increase by approximately 30% in late 2026 as demand for SAP-certified resources outstrips supply.

For a deeper look at what the ECC end-of-support deadline means operationally — including the specific modules affected and the extended maintenance terms — it is worth reviewing what SAP has confirmed as the final supported versions before committing to a timeline.

The Three Migration Paths: Greenfield, Brownfield, and Bluefield

The most consequential decision in any S/4HANA migration is the approach. Each path carries fundamentally different implications for timelines, costs, data continuity, and — critically — AI readiness.

Approach	What It Means	Market Share (ISG 2026)	AI Readiness
Greenfield	Full reimplementation from scratch. Processes redesigned. Selective data migration.	18%	Highest — clean slate enables full clean core and Joule from day one
Brownfield	System conversion of existing ECC. All historical data and customizations retained.	34%	Lowest initially — custom code must be remediated post-go-live to unlock AI features
Bluefield / SDT	Selective Data Transformation. New system built, only relevant data migrated. Hybrid of both.	~48%	High — allows clean core design while preserving critical historical data selectively

The plurality approach in 2026 is Bluefield — also called Selective Data Transformation — at approximately 48% of migrations according to ISG 2026 research. This reflects an industry finding its balance: organizations want the process redesign benefits of greenfield without abandoning decades of historical transaction data, and they want cleaner architecture than a straight brownfield conversion delivers. The brownfield path, chosen by 34%, remains common where speed and budget constraints are paramount and where the existing ECC configuration is relatively standard. Greenfield at 18% is the most transformative option, chosen by organizations willing to invest the time in a full reimplementation in exchange for the cleanest possible foundation.

Clean Core: The Non-Negotiable AI Prerequisite

Regardless of which migration approach you choose, one architectural principle determines whether you can access SAP's AI features: clean core. SAP defines clean core as keeping the S/4HANA system close to standard — avoiding direct ABAP modifications to core ERP code, and building any custom logic instead through SAP Business Technology Platform (BTP) extensions. It is not a nice-to-have; it is the access condition for SAP's embedded AI features, including SAP Joule.

This matters enormously in the context of a migration decision. A brownfield conversion that carries forward thousands of custom ABAP modifications from ECC will arrive at S/4HANA technically, but with an architecture that blocks or delays Joule adoption until those modifications are remediated. A greenfield or bluefield approach, by contrast, forces the clean core discipline up front — which means AI features are available from go-live rather than as a post-project remediation task.

The practical implication is that migration approach and AI strategy are not separable decisions. Choosing brownfield to save time now typically means paying for AI remediation work later — and the window to exploit early AI adoption is narrowed in the process. The full scope of what SAP Joule can do once clean core is in place — from procurement automation to financial closing assistance — illustrates what is at stake in that remediation delay.

The 60% Problem: Why Most Companies Are Getting This Wrong

According to research published by CIO/ISG in 2026, 60% of companies currently undergoing S/4HANA migrations are not integrating SAP Joule AI into their transition. A separate finding shows that 46% of those organizations have already discovered they need more time and budget than initially planned — suggesting that the combination of migration complexity and AI neglect is creating a compounding problem.

The reasons are understandable. Project teams under pressure to hit migration go-live dates tend to de-scope anything that feels optional. AI features that require clean core compliance can seem like a phase 2 problem when phase 1 is behind schedule. Stefan Maus, a consultant at Horváth, describes the pattern clearly: organizations "usually neglect" AI integration or "fail to integrate the topic holistically" during ERP transitions.

The cost of this sequencing error is significant. Joule is included in RISE with SAP licenses at no additional acquisition cost — the barrier to adoption is not price, it is configuration and clean core compliance. Organizations that defer Joule activation until after go-live are leaving a licensed, paid-for capability on the shelf while continuing to operate manual processes that Joule could be automating. For the broader picture of where AI and ERP are converging, the implication is clear: the ERP platform itself is becoming the AI platform, and treating them as separate workstreams is architecturally outdated.

Nestlé's Approach: Joule in Parallel, Not in Sequence

Nestlé is one of the publicly cited examples of a company integrating SAP Joule directly into its S/4HANA migration rather than treating it as a follow-on project. The principle behind this approach — which SAP CTO Philipp Herzig endorses explicitly — is that Joule adoption and migration execution should run in parallel, not in sequence.

In practice, this means the migration project team includes AI use case identification as part of the process design workstream. When a business process is being redesigned for S/4HANA — whether in procurement, finance, or supply chain — the question is not just "how should this process work in the new system?" but "which steps in this process can Joule handle, and what does that mean for how we staff and train for it?"

Herzig's specific recommendation is to focus initial Joule deployment on mass processing tasks and processes with standard use cases — areas where the AI has the highest confidence and the lowest risk of error. Supplier quote comparison, purchase order generation, and routine financial posting are the categories where early-stage Joule delivers demonstrable efficiency gains with minimal process risk.

A Practical Six-Step Migration Roadmap

Regardless of the approach chosen, a structured migration follows a consistent sequence. The key is ensuring AI readiness is embedded at each phase rather than treated as a separate track.

1. Readiness Assessment. Run SAP's Simplification Item Check and custom code analysis tools. Quantify the volume of ABAP modifications that will need remediation for clean core compliance. This determines whether greenfield, brownfield, or bluefield is the realistic choice — and sets the AI readiness baseline.
2. Migration Strategy and AI Use Case Selection. Choose the migration approach based on the readiness assessment, business process redesign ambition, and timeline constraints. Simultaneously identify two to three Joule use cases to activate at go-live — procurement, finance, or HR depending on the business priority.
3. Business Case and Budget Planning. Model total cost of ownership including clean core remediation effort, SAP BTP extension development, and the opportunity cost of deferred AI adoption. The 30% projected increase in consulting rates in late 2026 should be factored into any delayed start scenario.
4. Clean Core Implementation via BTP. Rebuild any essential custom logic as BTP extensions rather than ABAP modifications. This is the most technically intensive phase for heavily customized ECC environments. Data quality remediation for master data — customers, suppliers, materials — happens here.
5. Migration Execution with Parallel Joule Activation. Execute data migration, system configuration, and integration testing. Run Joule pilot on the pre-selected standard use cases in a parallel workstream. User training on both S/4HANA Fiori and Joule interaction patterns.
6. Post-Go-Live Optimization and AI Expansion. Stabilize the core system, then expand Joule adoption to additional use cases based on the pilot results. The migration itself is the foundation; the AI roadmap is the building that gets constructed on top.

RISE with SAP: The Deployment Decision That Shapes Everything

Alongside the greenfield/brownfield/bluefield decision, the deployment model matters enormously for AI readiness: public cloud, private cloud, RISE with SAP, or on-premise S/4HANA are not interchangeable.

RISE with SAP — SAP's managed cloud subscription offering — bundles S/4HANA Cloud Private Edition, BTP credits, SAP Business Network access, and the tools needed for clean core migration into a single contract. Critically for AI readiness, Joule is included in RISE licenses and receives its most frequent feature updates in the cloud context. On-premise S/4HANA deployments can access Joule, but the feature cadence is slower and the integration with BTP requires more manual configuration.

The strategic implications of RISE with SAP extend beyond the migration project itself. Organizations that move to RISE are committing to SAP's managed upgrade cycle, which means they receive AI feature updates without major upgrade projects — the platform continuously improves. On-premise organizations retain control but take on the upgrade responsibility themselves.

What to Prioritize Right Now

For organizations that have not yet started their S/4HANA journey, the most valuable immediate action is a scoping exercise that produces three outputs: a custom code inventory (how much ABAP modification exists and how complex it is), a process prioritization map (which processes are strategic candidates for redesign versus which should be converted as-is), and an initial Joule use case shortlist (two or three high-volume standard processes where AI activation at go-live is feasible).

For organizations already mid-migration, the question is whether there is still time to incorporate clean core compliance for the highest-priority AI use cases before go-live. Even if the full custom code inventory cannot be remediated before go-live, prioritizing clean core for the two or three processes where Joule activation is planned can deliver meaningful AI capability at launch rather than deferring it entirely.

The broader transformation context matters here too. The shift from ECC to S/4HANA is not a technology refresh — it is the foundational move that determines whether your enterprise can operate at the pace that AI-driven autonomous operations will require over the next five years. The organizations treating this migration as a compliance exercise will arrive at S/4HANA without the architecture to capitalize on it. The ones treating it as a strategic platform decision will arrive ready.