The adoption numbers that explain the forecast
SAP confirmed back in 2023 that it would not extend the ECC mainstream maintenance deadline again, which gave the installed base roughly four years of clear notice. By the end of 2024, only 39% of that base, about 14,000 of 35,000 enterprises, had actually purchased an S/4HANA transition license. A license signals budget approval and intent, not a finished migration, and Gartner's projection that 17,000 companies will miss the 2027 deadline follows directly from how slowly that adoption curve has moved.
Gartner VP Fabio Di Capua put the industry's own track record bluntly: SAP has had fifteen years to convince its base to migrate and converted less than half. That history matters because it undercuts any assumption that the remaining 61% will suddenly move faster in the final stretch. Enterprises that have not started are not behind a normal project timeline, they are behind a timeline that most of their peers have also missed.
Why migrations keep blowing through their own schedules
The Horvath study surveyed 200 SAP user companies already underway and found projects running about 30% longer than planned, with over 60% exceeding budget and only 37 of the 200 having actually completed their migration. Separate ISG research from February 2026 found similar numbers: nearly 60% of projects delayed and over budget, with two-thirds still in the planning phase. These are not outlier companies with unusually bad luck, this is the typical outcome.
Forrester's Akshara Naik Lopez frames the real risk accurately: support from SAP is ending for the product, not the product itself. Nothing breaks on January 1, 2028. What changes is that new vulnerabilities stop getting patched and new regulatory requirements stop getting addressed, a slow bleed that typically shows up in an audit finding twelve to twenty four months later rather than an outage the next morning.
The two migration packages are not a shortcut
SAP markets RISE with SAP for larger, complex ECC customers moving to S/4HANA private cloud, with managed infrastructure and migration tooling bundled in, and GROW with SAP for mid-market customers moving to the public cloud edition with standardized, less customized processes. Neither is inherently cheaper than the other, despite marketing that sometimes implies RISE is the premium path and GROW the budget one. The right choice depends on how much custom logic your ECC instance carries, not on sticker price.
SAP's own Arne Schmidthals describes private cloud as the usual path for existing SAP ERP customers, which signals where SAP wants its base to land, but usual is not the same as cheapest or fastest for every customer. A private edition transition option announced in Q1 2025 is limited to select large customers willing to commit to a RISE agreement and a 2030 HANA deadline, a narrower door than most enterprises assume is open to them.
What extended maintenance actually buys you, and who qualifies
Extended Maintenance runs from January 1, 2028 through December 31, 2030 and includes security patches and legal updates, but it is only available for support packs EHP 6 through 8, adds roughly two percentage points to the maintenance fee, and must be elected in advance rather than purchased after the deadline passes. Enterprises running EHP 0 through 5 have no extended maintenance option at all; their mainstream maintenance already ended December 31, 2025.
The default fallback after the 2027 deadline, Customer-Specific Maintenance, costs the same as mainstream maintenance but delivers much narrower coverage, which makes it a worse deal than extended maintenance for anyone who actually qualifies for the extension and simply has not elected it yet. Third party support from vendors like Rimini Street, priced around half of SAP's rate through 2040, is a real alternative for ECC instances the business has decided not to touch again, but it forecloses any future SAP-native upgrade path.
The decision CIOs need to force this quarter
The practical deadline that matters right now is the window to elect Extended Maintenance in advance, a choice that has to be made before mainstream support ends rather than after, which makes it more urgent than the headline December 2027 date suggests. Any enterprise still running EHP 6 through 8 ECC without a migration plan locked in needs to decide this quarter whether it is migrating, electing extended maintenance, or moving to third party support, because waiting past that election window removes the cheapest fallback option entirely.
Given that only 8% of migration projects in the Horvath study finished on schedule, any CIO who assumes their organization's timeline will be the exception is making a bet against the industry's own documented track record. The more honest planning assumption, backed by two independent studies now, is that your migration will run roughly a third longer and cost more than your current budget approval assumes, and that assumption should shape the deadline you commit to internally, not the one SAP prints in its press releases.
