What the studies found
ISG reached that figure in its 2026 State of SAP Migrations report, published 27 March 2026 by Stanton Jones and Stacey Cadigan.
This document collects five outside studies on how SAP ECC and S/4HANA transformations actually finish, with every source printed and linked. It is written for the CIOs, CFOs and IT leaders who have to tell a board what the program will cost and how long it will take.
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What is inside
- The ISG split: ISG found 58 percent of SAP migrations run both over budget and behind schedule, 27 percent miss one of the two, and 15 percent land on time and on budget.
- Schedule and quality: Horváth surveyed 200 SAP-running companies in Q1 2025 and found completed S/4HANA transformations ran on average 30 percent longer than planned, with 65 percent reporting strong to very strong quality deficits afterward.
- How manufacturers chose: In the same Horváth study, greenfield led overall at 37 percent, but manufacturing companies and firms above 5 billion euros in annual sales mostly chose the brownfield Catch up the Core approach.
- The maintenance clock: SAP announced on 4 February 2020 that mainstream maintenance for Business Suite 7 runs through the end of 2027, with optional extended maintenance to 2030 at two percentage points above the existing base.
- Who is still on ECC: Gartner, reported by Grant Gross in CIO on 4 June 2025, put roughly 14,000 of 35,000 ECC customers as migrated by the end of 2024 and projects 17,000 still on ECC when maintenance ends in 2027.
Sources cited in full inside the document
- ISG
- Horváth
- Gartner, via CIO
- SAP SE
- Precisely and ASUG
Five of the six sections are outside research, each with its source printed so you can check the figure yourself. LeapGreat’s own work appears in one section, labeled as such.
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