next-lint Doesn't Support ESLint 9 about next.js

[elmarsto]

Bumping this, it is breaking package update automation at my corp

[GabenGar]

Yeah it's breaking change because ESLint 9.0.0 is a major release with a ton of breaking changes. You better hope NextJS didn't adhoc around every single ESLint implementation detail, so the migration to the newest version wouldn't take forever on their end.
For now a "fix" is to update next and eslint-config-next to 14.2.1 which limits the range of required ESLint version to eslint@"^7.23.0 || ^8.0.0" and therefore will crash on install/update instead.

[davidjulakidze]

Bumping this for visibility, it does not seem to prevent build but unsure of the impact.

✓ Compiled successfully
   Linting and checking validity of types  .. 
⨯ ESLint: Invalid Options: - Unknown options: useEslintrc, extensions - 'extensions' has been removed.
✓ Linting and checking validity of type

"next": "^14.2.0",
"eslint-config-next": "^14.2.0",
"eslint": "^9.0.0",

{
  "extends": "next/core-web-vitals"
}

[SukkaW]

IMHO, the adoption should be done gradually in the following steps:

• Migrate eslint-config-next, so it exposes both the legacy eslintrc config and the new flat config.
• Change Next.js internal ESLint implementation, allows it to accept both the legacy config .eslintrc and the new flat config eslint.config.js.
• Change next lint so that it can accept eslint.config.js
• Change create-next-app built-in template to use eslint.config.js
• Change Next.js example to use eslint.config.js

[BnAmN]

IMHO, the adoption should be done gradually in the following steps:

• Migrate eslint-config-next, so it exposes both the legacy eslintrc config and the new flat config.

• Change Next.js internal ESLint implementation, allows it to accept both the legacy config .eslintrc and the new flat config eslint.config.js.

• Change next lint so that it can accept eslint.config.js

• Change create-next-app built-in template to use eslint.config.js

• Change Next.js example to use eslint.config.js

I would like to add that the new flat config file can have multiple names:

• eslint.config.js
• eslint.config.mjs
• eslint.config.cjs

Source: https://eslint.org/docs/latest/use/configure/configuration-files#configuration-file