OpenAI reports strong internal results for GPT-6.1 Sol migrating COBOL to modern languages
OpenAI published a blog post reporting that its GPT-6.1 Sol model achieved 87% behavior-preservation accuracy on COBOL-to-modern-language migrations at low reasoning effort and up to 98% at higher effort in its internal tests, and said migrations are judged successful only if all tests pass. The article notes Anthropic has promoted a COBOL modernization playbook and Claude Code without public benchmarks, and experts cautioned these results do not yet solve the broader, risky engineering challenge of replacing critical legacy systems.