This is part of the new version in react. I also had files "reportWebVitals" and "setupTests", I deleted them and everything works properly.

With "reportWebVitals" you can track real user performance on your site. And with "setupTests" you are Initializing Test Environment

this feature is available with react-scripts@4.0.0 and higher

I do not need these properties, just deleted them and that's it, the eslintcache can not be deleted is part of the bundle.

It seems as new issue in React App (this issue opened on Nov 27, 2020)

Put .eslintcache in .gitignore also do:

git rm -rf --cached .eslintcache
git add .

git rm: remove files from working tree ...

-r: recursive removal in case of a directory name ...

-f or -force: Override the up-to-date check.

Details: https://git-scm.com/docs/git-rm

This file is part of the new version of create-react-app package, you can't avoid it to be added, just like other files being added. This is the bundle.

It is part of the CRA bundle. I'd recommend just adding it to the .gitignore file if it isn't in there already.

From the ESLint docs:

Store the info about processed files in order to only operate on the changed ones. The cache is stored in .eslintcache by default. Enabling this option can dramatically improve ESLint's running time by ensuring that only changed files are linted.

I faced the problem, tried putting .eslintcache in .gitignore and implement the command git add . but was not enough, because you should do git add . after every change in your code, and that's not sence at all of course, this is not a clean workround anyway.

So, simply i downgraded the react-scripts to @4.0.0, and that problem disapeared completely I think the react-scripts@4+ isn't stable yet

I ended up writing a custom plugin to delete the .eslintcache before each watch compile:

var exec = require("child_process").execSync;

module.exports = class ESLintClearPlugin {
  constructor(options) {
    this.options = options;
  }
  apply(compiler) {
    compiler.hooks.watchRun.tap("ESLintClearPlugin", () => {
      exec("del .eslintcache");
    });
  }
};

Then you use it in your webpack config:

const ESLintClearPlugin = require("./pathtofile");
// webpack config    
plugins: [new ESLintClearPlugin()]