Error: .plugins[0][1] must be an object, false, or undefined

I’ve updated Next from version 5 to 6 and on build I get:

Error: .plugins[4][1] must be an object, false, or undefined
    at assertPluginItem (/node_modules/@babel/core/lib/config/validation/option-assertions.js:157:15)
    at /node_modules/@babel/core/lib/config/validation/option-assertions.js:134:14
    at Array.forEach (<anonymous>)
    at assertPluginList (/node_modules/@babel/core/lib/config/validation/option-assertions.js:133:9)
    at /node_modules/@babel/core/lib/config/validation/options.js:84:20
    at Array.forEach (<anonymous>)
    at validate (/node_modules/@babel/core/lib/config/validation/options.js:62:21)
    at /node_modules/@babel/core/lib/config/config-chain.js:141:36
    at cachedFunction (/node_modules/@babel/core/lib/config/caching.js:40:17)
    at init (/node_modules/@babel/core/lib/config/config-chain.js:122:12)
    at /node_modules/@babel/core/lib/config/config-chain.js:206:17
    at buildRootChain (/node_modules/@babel/core/lib/config/config-chain.js:85:20)
    at loadPrivatePartialConfig (/node_modules/@babel/core/lib/config/partial.js:41:53)
    at loadPartialConfig (/node_modules/@babel/core/lib/config/partial.js:66:16)
    at babelConfig (/node_modules/next/dist/server/build/webpack.js:88:57)
    at _callee2$ (/node_modules/next/dist/server/build/webpack.js:164:34)

My babel deps are:

    "babel-eslint": "^8.2.3",
    "babel-plugin-inline-react-svg": "^0.5.2",
    "babel-plugin-transform-class-properties": "^6.24.1",
    "babel-plugin-transform-decorators-legacy": "^1.3.4",
    "babel-preset-env": "^1.6.1",
    "babel-root-import": "^4.1.8",
    "markdown-in-js": "1.1.4",

.babelrc

{
  "presets": [
    "env",
    "next/babel"
  ],
  "plugins": [
    "markdown-in-js/babel",
    "inline-react-svg",
    "transform-decorators-legacy",
    "transform-class-properties",
    ["babel-root-import", [{
      "rootPathPrefix": "~",
      "rootPathSuffix": "."
    }, {
      "rootPathPrefix": "$",
      "rootPathSuffix": "app"
    }, {
      "rootPathPrefix": "#",
      "rootPathSuffix": "shared"
    }]]
  ]
}

Tech	Version
next	6
node	v8.9.3
OS	macOS H.S.

[brentmclark]

@foxhound87 did babel-upgrade install babel-core": "^7.0.0-bridge.0? I don’t see it in your list, and I’m pretty sure it’s absence will muck with the non-scoped packages (e.g. babel-eslint)

[foxhound87]

I updated to next 7 and the babel deps using babel-upgrade, the app is building and running correctly locally (also in docker container, using nanobox), but when deployed (same environment) I get the usual error:

Module build failed (from ./node_modules/next/dist/build/webpack/loaders/next-babel-loader.js):
 Error: .plugins[0][1] must be an object, false, or undefined

This is my new babel.config.js:

module.exports = {
  presets: [
    'next/babel',
  ],
  plugins: [
    'markdown-in-js/babel',
    'inline-react-svg',
    ['@babel/plugin-proposal-decorators', { legacy: true }],
    ['@babel/plugin-proposal-class-properties', { loose: true }],
  ],
};

I’m not using all the plugins installed by babel-upgrade. Just what I need.

the packages installed by babel-upgrade in devDependencies are:

    "@babel/core": "^7.1.2",
    "@babel/plugin-proposal-class-properties": "^7.0.0",
    "@babel/plugin-proposal-decorators": "^7.0.0",
    "@babel/plugin-proposal-do-expressions": "^7.0.0",
    "@babel/plugin-proposal-export-default-from": "^7.0.0",
    "@babel/plugin-proposal-export-namespace-from": "^7.0.0",
    "@babel/plugin-proposal-function-bind": "^7.0.0",
    "@babel/plugin-proposal-function-sent": "^7.0.0",
    "@babel/plugin-proposal-json-strings": "^7.0.0",
    "@babel/plugin-proposal-logical-assignment-operators": "^7.0.0",
    "@babel/plugin-proposal-nullish-coalescing-operator": "^7.0.0",
    "@babel/plugin-proposal-numeric-separator": "^7.0.0",
    "@babel/plugin-proposal-optional-chaining": "^7.0.0",
    "@babel/plugin-proposal-pipeline-operator": "^7.0.0",
    "@babel/plugin-proposal-throw-expressions": "^7.0.0",
    "@babel/plugin-syntax-dynamic-import": "^7.0.0",
    "@babel/plugin-syntax-import-meta": "^7.0.0",
    "@babel/preset-env": "^7.1.0",
    "babel-eslint": "^10.0.1",
    "babel-loader": "^8.0.4",
    "babel-plugin-inline-react-svg": "^0.5.4",

really can’t understand what’s still wrong! This error is still preventing me to update next. I also reduced the number of the plugins used in the babel config file.