Web Development
Bug Report
ESLint 9 "couldn't find an eslint.config" after upgrading: migrating to flat config with TypeScript
A routine dependency update moved us to ESLint 9, and lint failed in CI and every editor: ESLint couldn't find an eslint.config file. ESLint 9 uses flat config by default and ignores .eslintrc. How we migrated a TypeScript and React project, kept Prettier out of the way, and avoided the common traps.