Ionic android build fails with Could not find plugin "proposal-numeric-separator"

This is how i fixed the exact same exception :

1-Open package.json and add

 "resolutions": {
  "@babel/preset-env": "^7.8.7"

 "dependencies": {..}

2- run npx npm-force-resolutions

3- run npm install

Now you're good to go..

Change your tsconfig.json file target value

form { "target": "es2015" } to { "target": "es5" }

this work for me.

After a few try :

  1. Install npm i @babel/plugin-proposal-numeric-separator
  2. Go to node_modules/@babel/preset-env/lib/available-plugins.js
  3. Add var _pluginTransformNumericSeperator = _interopRequireDefault(require("@babel/plugin-proposal-numeric-separator"));
  4. And add "proposal-numeric-separator": _pluginTransformNumericSeperator to default variable