Nearly 60 percent of SAP migration projects are delayed and over budget as organisations underestimate complexity, allow expansion of scope, and fail to understand internal constraints, according to research from ISG.

The survey of 200 senior decision-makers in large global companies also found that fewer than one in five organisations reimplement SAP processes and technology when they move to the latest platform, S/4HANA.

Nearly half (49 percent) carry out little or no re-engineering, choosing instead to preserve legacy processes and data.

The research comes as SAP users face the support deadline for ECC, the legacy ERP platform still used by thousands of the world’s largest businesses. By the end of 2027, mainstream support is stopping while extended support at a 2 percent premium will be available until the end of 2030. SAP has also discussed another support option beyond 2030 so long as customers sign up to its migration commercials ahead of that date.

Gartner data shows 39 percent of SAP’s 35,000 ECC customers worldwide had yet to migrate as of Q4 2024, nearly a decade after S/4HANA launched in 2015.

Yet the majority of the largest organisations are still failing to stick to budgets and timelines with migration to S/4HANA.

Michael Dornan, ISG principal analyst, said even simply moving their current processes to a new platform, organisations struggled with making a plan and sticking to it.

“Some of them are trying to do this quickly, a lift-and-shift as fast and cheap as possible. This group often underestimated the complexity, scope and the constraints they have. They also suffer from scope creep and changing requirements as they go through. A lot of the delays are caused by people, not necessarily the technology.”

According to the research, 34 percent of organisations were opting for “brownfield” migrations. Eighteen percent wanted to adopt a greenfield strategy, embracing standard processes in SAP’s preferred “clean core” approach. Nearly half, however, were mixing the two approaches, so-called “bluefield.”

Dornan said more than half the survey respondents agreed they had over-customised legacy ERP to the point where standardisation now feels risky to the business.

“That’s the fear they go through. If you standardise, then you just start that whole process again. There are a lot of stakeholders in the business that actually felt that their old ERP was doing the job that they wanted to, which creates inertia,” he said.

The report states that brownfield and hybrid approaches might limit long-term benefits and make it more difficult to adopt newer technologies such as AI.

“Fragmented processes, extensive customisations, and legacy data structures often constrain which AI use cases can be effectively deployed after go-live. By contrast, environments with standardised processes and well-governed data are better positioned to realise the automation, forecasting, and operational efficiency gains enterprises expect.”

However, businesses are carefully weighing up the risks and refusing to be dictated by the vendors’ timelines.

Of the total sample of SAP ERP users, eight percent planned to stay on ECC beyond 2027 while around two-thirds were still in the planning stage for migration, making it unlikely they would make the cut-off for mainstream support.

The trend is borne out elsewhere. Airbus, for example, currently runs a patchwork of SAP versions, including legacy SAP R/3 4.6 and ECC 6.0 systems. While some divisions – finance, materials management, and parts of Airbus Helicopters – have already moved to S/4HANA, the bulk of the migration lies ahead. The company said it may not be finished by 2030.

Like thousands of other SAP users, it is trying to find the right balance between the risks of changing and the risks of staying the same.