Gartner analysts are warning that a massive bubble is forming around AI-powered mainframe migration projects. The research firm predicts that most enterprises turning to generative AI to migrate legacy code to alternative platforms will face significant disappointment.
According to a recent Gartner paper titled “Too Big to Fail: Why Mainframe Exit Projects Are Likely to Fail in the Age of Generative AI,” more than 70 percent of mainframe exit projects launched in 2026 will fail to achieve their intended goals. The firm attributes this failure to an overestimation of what generative AI tooling can actually accomplish.
The market for these AI-driven migrations is also expected to contract sharply. Gartner forecasts that by 2030, 75 percent of vendors operating in the mainframe exit market will either cease to exist or be forced to pivot their business models.
The complexity of legacy data
Analysts Dennis Smith, Alessandro Galimberti, and Tobi Bet argue that the sheer scale of mission-critical applications makes wholesale migration a physical and financial impossibility for most large-scale enterprises. They note that the volume and interconnected complexity of mainframe data pose insurmountable hurdles.
While the team acknowledges that generative AI is effective at detecting and describing technical debt, they find the technology has "significant limitations when it comes to the automated conversion and migration of legacy code." The researchers also noted that AI fails to account for unique mainframe capabilities, such as maintaining specific performance and throughput levels after a move.
As reported by theregister.com, Gartner suggests that vendor hype is being driven by aggressive investor demand for AI capabilities. This pressure forces vendors to deploy AI even when it is unnecessary, meeting a market of users who are struggling to find staff to operate aging mainframe systems.
Gartner warns of a dangerous gap between the "marketing promise" of generative AI and its actual code transformation capabilities. The analysts stated that poor decision-making in migration is not just a budget issue but "a threat to business and operational continuity."
Instead of seeking a "seemingly magical solution," the firm advises a platform-smart approach that evaluates workloads individually. The report suggests that the drive to abandon mainframes is actually diminishing as customers realize the near-impossibility of exiting the platform at an acceptable cost and risk.
This outlook stands in contrast to recent market speculation. IBM’s stock recently faced pressure after Anthropic promoted the COBOL-conversion abilities of its Claude Code tool, leading to rumors that the mainframe era might be ending. However, Gartner maintains that the mainframe remains the leading platform for certain mission-critical applications, even alongside the rise of cloud-native architectures.
