A brownfield S/4HANA migration does not need a greenfield data-migration army. It needs strong Basis people for the SUM-DMO run, ABAP developers to remediate the custom code you're carrying forward, and the two functional consultants who remember why a 14-year-old custom Z-table exists. This is a hiring problem before it's an IT problem.

TL;DR: Pattern-match the hire to the path. Brownfield is technical-conversion-heavy, greenfield is functional-design-heavy. Hire backwards from go-live, keep the legacy-config knowledge in-house permanently, and start in 2026 if you want any chance at an end-2027 cutover.

Brownfield, greenfield, or bluefield — and why your hiring plan changes with the answer

Your migration path dictates your shopping list. A brownfield system conversion typically runs 12-18 months for a focused conversion and is technically heavy: strong Basis/SUM-DMO resources plus ABAP custom-code remediation, with roughly 20-40% of custom objects needing work (Basis Admin, 2025). Greenfield, by contrast, is functional-design-heavy.

That distinction is the whole game when you write a job spec. Brownfield converts your existing ECC system in place. You keep your data, your historical config, and most of your custom development, then technically lift it onto S/4HANA. Greenfield rebuilds from a clean core. Bluefield sits between the two, selectively migrating data into a new shell.

Each path wants a different person. A greenfield programme leans on process-redesign consultants and change managers who run workshops and define fresh config. A brownfield programme leans on people who can read a 14-year-old ECC system and decide what survives the conversion. Hand a greenfield CV to a brownfield cutover and you've hired the wrong instinct.

Most articles on this topic argue about which migration approach is "best." That's a systems-integrator question. The recruiter's question is narrower and more useful: given the path you've already chosen, who do you actually need in the room?

That's the lens behind how I run SAP recruitment: start from the migration path, then the people it actually demands.

What roles a brownfield S/4HANA programme actually needs

Four role clusters carry a brownfield conversion, and the technical core is non-negotiable. The work is technically heavy: strong Basis/SUM-DMO resources plus ABAP custom-code remediation, with roughly 20-40% of custom objects requiring some level of work, run through ATC (Basis Admin, 2025). Get those two clusters wrong and the conversion stalls.

Basis and technical conversion

This is the spine of a brownfield run. You need Basis engineers who have actually driven a Software Update Manager with Database Migration Option (SUM-DMO) through a real cutover, not just a sandbox. They manage the conversion runtime, the downtime window, the dual-stack split if you're on one, and the dozens of small technical failures that surface at 2am during go-live weekend. In the last two years of SAP searches I've run, this is the cluster clients most often under-spec and most regret under-specing.

ABAP custom-code remediation

Brownfield carries your custom development forward, and most of it needs attention. Expect 20-40% of custom objects to require remediation, surfaced through the ABAP Test Cockpit (ATC) (Basis Admin, 2025). You need ABAP developers who can read legacy code, fix what HANA and the simplified data model break, and quietly retire what nobody uses anymore. This is forensic work, not green-field building.

Functional consultants who know your legacy config

Here's the role nobody writes a clean job description for. You need functional consultants who understand the specific ECC config you're carrying over, MM, SD, FI, or the warehouse setup, and why it was built that way. A conversion does not need someone to redesign your processes. It needs someone who remembers why the Z-table exists before they delete it.

Programme and governance lead

One person owns the timeline, the cutover plan, and the testing discipline. Weak project management is a named root cause of failed migrations, which I'll come back to. This role keeps the technical and functional clusters pulling in one direction against a fixed deadline.

A brownfield conversion is staffed like a renovation, not a new build. The most valuable hire is rarely the one with the flashiest S/4HANA certification. It's the consultant who can walk your existing system and tell you, accurately, what will break.

The skills split: ECC institutional knowledge vs new S/4HANA capability

The hard part of a brownfield hire is the overlap, and the market does not produce it cleanly. UKISUG found 92% of organisations see existing customisations as problematic to their S/4HANA path, and 71% of those yet to migrate feared a skills shortage would slow them down (UKISUG via Computer Weekly, 2021). You need both old knowledge and new.

A brownfield hire sits on two axes. One axis is institutional ECC knowledge: how your config evolved, which custom objects matter, what the business actually relies on. The other is current S/4HANA capability: the new data model, Fiori, the simplified tables, the conversion tooling. Pure ECC veterans miss the new architecture. Pure S/4HANA hires miss your history.

The risk hides in the gap. Resulting IT's 2026 SAP Success Report, drawing on 113 professionals across 105 organisations with ex-Gartner Dr Derek Prior, found 48% of respondents felt their architecture teams lacked the solution knowledge to define the right SAP design (Resulting IT, 2026). A CV that says "SAP S/4HANA" tells you almost nothing about whether someone can convert your specific system.

So filter on demonstrated end-to-end conversion experience, not keywords. Ask candidates to describe a cutover they actually owned: what broke, what they cut, what they kept. The people who've done it answer in concrete detail. The people who haven't answer in methodology slides.

Permanent or contract? Why brownfield tilts toward retention

Split the decision by what survives go-live. Time-boxed conversion work scales down after cutover. The knowledge you need to run and optimise the system past 2027 does not. With only 8% of completed S/4HANA transitions finishing on schedule (Horvath via CIO.com, 2025), the wrong staffing mix is a reliable way to overrun.

Contract suits the spiky, technical, time-boxed work. The SUM-DMO run, the cutover weekend, the bulk of ABAP remediation: these peak hard during the conversion and shrink afterwards. Bringing in external contract capacity that scales down post go-live is the right call here. You don't want a permanent headcount built around a one-off conversion task.

Permanent suits the knowledge you must retain. The functional and config knowledge, the people who understand why your legacy setup is the way it is, is the part to hire onto the payroll. Tie this back to the institutional-knowledge question: keep in-house the people who can answer "why does this work like this?" long after the integrator has rolled off.

The cheapest mistake I see is the inverse: hiring permanent staff for the cutover sprint and renting the institutional knowledge. After go-live, the spike-work hires sit idle and the rented memory walks out the door with the contract. Invert it.

Getting that split right is most of what I do on a retained SAP search: scoping which roles to keep permanent before the first CV goes out.

Why these searches are genuinely hard right now

The supply is thin and everyone is buying at once. Eurostat reports that 57.5% of EU enterprises that tried to recruit ICT specialists in 2023 had difficulty filling the roles, with lack of applications and qualifications the top barriers (Eurostat, 2024). Niche SAP conversion skills sit at the scarce end of an already-scarce pool.

The talent is also geographically concentrated. In 2025 more than 10 million people worked as ICT specialists across the EU, with Germany holding 22.2% of the total (2.3 million) and France 13.7% (Eurostat, 2025). That's where the deepest SAP supply sits, which matters if your search is open across Germany or anchored in Romania.

Then there's demand timing. Adoption has reached 59% fully or partially live, up 13 percentage points from 2024 (Precisely with ASUG, 2025). The remaining 40-50% are all hiring for the same conversion-experienced people, inside the same narrow window, before the same deadline. Scarcity and synchronised demand are a brutal combination.

This is the honest case for working with a recruiter who goes deep rather than wide. When the pool is this thin, volume sourcing doesn't help. You need someone who already knows where the conversion-experienced EWM or Basis people are and can approach the handful who fit. Three CVs that fit beats thirty that don't.

The 2027 ECC deadline is a hiring deadline, not just an IT one

The clock is external and fixed, which changes everything about timing. SAP ECC 6.0 / Business Suite 7 mainstream maintenance ends 31 December 2027; EHP 6-8 can buy extended maintenance only to end-2030, at an additional fee of roughly two percentage points, around a 9% uplift (Rimini Street, 2025). Your staffing date isn't set by your roadmap. It's set by SAP's.

There's an earlier date most teams overlook. SAP set a final transition period for S/4HANA on-premise Compatibility Packs usage rights, moving the expiry to 31 May 2026 under SAP Note 2269324, declared final with no further extensions (SAP News, 2025). If your conversion leans on Compatibility Pack functionality, that cutoff is the real constraint, not 2027.

Now look at how many haven't moved. Per Gartner, only about 39% of ECC customers, roughly 14,000 of 35,000, had migrated by end of 2024, with about 17,000 holdouts, nearly half the base, projected to still be on ECC by 2027 (Gartner via CIO.com, 2025). Every one of those holdouts that does move is competing for your hire.

So treat the maintenance date as a hiring date. The question isn't "when do we want to migrate?" It's "given a fixed external deadline and a scarce talent pool, when must the team already be in place?" That's a recruiting calculation, and it runs backwards from go-live.

When to start hiring against an 18-36 month migration

Hire backwards from go-live, not forwards from today. A brownfield conversion runs 12-18 months for a focused effort and 18-36 months at enterprise scale (Basis Admin, 2025). A senior SAP hire in a thin niche pool takes well over a month to source and longer to onboard. If the team isn't assembling in 2026, an end-2027 cutover is already at risk.

Do the arithmetic plainly. Take an end-2027 go-live. Subtract an 18-month conversion and you need the core team productive by mid-2026. Subtract sourcing and onboarding for senior, scarce roles and your search has to open in early 2026 at the latest. Enterprise-scale programmes at 36 months should already be staffing.

The failure data backs the urgency. Horvath's Q1 2025 study of 200 large companies found only 8% delivered on schedule, around 65% blew the budget, projects ran roughly 30% longer than planned, and 65% reported severe quality deficiencies, with lack of specialist-department personnel a named cause (Horvath via CIO.com, 2025). Thin teams are why projects overrun.

The clients who start their search early aren't the ones with the biggest budgets. They're the ones who understood that the 2027 date sets the recruiting calendar, not the IT calendar. By the time a programme is "ready to hire," the conversion-experienced shortlist has usually already been hired by someone who started six months sooner.

Common questions

What roles does an S/4HANA brownfield migration team actually need?

Four clusters: Basis/technical for the SUM-DMO conversion run, ABAP developers for custom-code remediation (20-40% of objects typically need work, per Basis Admin, 2025), functional consultants who know your legacy ECC config, and a programme lead owning timeline and testing. The technical clusters are non-negotiable.

How does brownfield staffing differ from greenfield staffing?

Brownfield is technical-conversion-heavy; greenfield is functional-design-heavy (Basis Admin, 2025). Brownfield wants Basis engineers and ABAP remediators who can read and convert your existing system. Greenfield wants process-redesign consultants and change managers building fresh config. A greenfield CV is the wrong instinct for a conversion cutover.

Should brownfield migration hires be permanent or contract?

Split by what survives go-live. Time-boxed conversion work, the SUM-DMO run and most ABAP remediation, suits contract capacity that scales down afterward. The functional and config knowledge you must retain to run the system past 2027 should be permanent. Given only 8% of transitions finish on schedule (Horvath via CIO.com, 2025), retention matters.

Why are S/4HANA brownfield hires so hard to find before 2027?

Supply and demand collide now. Adoption is at 59% live, up 13 points from 2024 (Precisely with ASUG, 2025), so the remaining holdouts compete for the same finite, conversion-experienced pool. Eurostat found 57.5% of EU enterprises struggled to fill ICT roles in 2023 (Eurostat, 2024).

When should you start hiring relative to the migration timeline?

Work backwards from go-live. For an end-2027 cutover with an 18-month conversion (Basis Admin, 2025), the core team needs to be productive by mid-2026, so your search opens in early 2026. Enterprise-scale 36-month programmes should already be staffing now, in 2026.

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If you're scoping a brownfield conversion and want to talk through the team before you write the job specs, tell me about your migration. I work a small number of SAP searches at a time, and I'd rather help you hire the right three people than send you thirty CVs that don't fit.