ESLint 10.0.0 is out, and the old eslintrc configuration system is gone for good. The .eslintrc files and .eslintignore are no longer read, and the old flags and environment variable that kept it alive are gone. The release also drops Node.js versions before 20.19 and starts looking for a config file from each linted file's own directory rather than the working directory, which is a real improvement for repositories that hold many projects.
I think the removal is the useful part. The flat config format has been the default for a long time. A team still carrying eslintrc files in 2026 does not have an ESLint problem. It has a tooling debt problem, and this is the kind of release that turns a debt you can ignore into one you cannot.
My view is to treat it as an opportunity rather than a chore. Most teams with several repositories have several slightly different lint configurations that drifted apart over years. The forced migration is the one moment when consolidating them into a single shared config costs nothing extra, because every repository has to be touched anyway.
When a tool you depend on forces an upgrade, does your team do the minimum to get green, or use the moment to clean up?
Photo source: https://photos.robertstowe.com/paris