ionic serve: @ionic/app-scripts isn't installed in this project, but it is.

[tonysamperi]

Description:
ionic serve: @ionic/app-scripts isn't installed in this project, but it is.
I started having the issue right after upgrading ionic-cli

Steps to Reproduce:
Update from ionic@3.9.2 to ionic@4.0.1
On a project created with ionic@3.9.2

Output:

ERROR] @ionic/app-scripts is required for ionic serve to work properly.

        Looks like @ionic/app-scripts isn't installed in this project.

        This package is required for ionic serve in ionic/angular 4 projects.

ioni
My ionic info:
I was downgrading while creating this question...Didn't see this. Sorry.
This is the info after downgrade:

cli packages: (C:\nvm\v6.14.2\node_modules)

    @ionic/cli-utils  : 1.9.2
    ionic (Ionic CLI) : 3.9.2

global packages:

    Cordova CLI : not installed
    Gulp CLI    : not installed globally

local packages:

    @ionic/app-scripts : 3.1.10
    Cordova Platforms  : none
    Ionic Framework    : ionic-angular 3.9.2

System:

    Node : v6.14.2
    npm  : 3.10.10
    OS   : Windows 10

Other Information:
When I downgraded I simply ran npm i -g ionic@3.9.2

[imhoffd]

Can you paste the list of files in the node_modules/.bin directory in your project?

[theunreal]

Same here, no idea why it just started. CLI 4.

[theunreal]

List of files in node .bin:

acorn
acorn.cmd
atob
atob.cmd
autoprefixer-info
autoprefixer-info.cmd
browserslist
browserslist.cmd
build-optimizer
build-optimizer.cmd
create
create.cmd
errno
errno.cmd
esparse
esparse.cmd
esvalidate
esvalidate.cmd
har-validator
har-validator.cmd
in-install
in-install.cmd
in-publish
in-publish.cmd
ionic-app-scripts
ionic-app-scripts.cmd
js-yaml
js-yaml.cmd
json5
json5.cmd
miller-rabin
miller-rabin.cmd
mime
mime.cmd
mkdirp
mkdirp.cmd
ng-xi18n
ng-xi18n.cmd
ngc
ngc.cmd
node-gyp
node-gyp.cmd
node-sass
node-sass.cmd
nopt
nopt.cmd
not-in-install
not-in-install.cmd
not-in-publish
not-in-publish.cmd
pbjs
pbjs.cmd
purify
purify.cmd
rimraf
rimraf.cmd
rollup
rollup.cmd
sassgraph
sassgraph.cmd
semver
semver.cmd
sha.js
sha.js.cmd
sshpk-conv
sshpk-conv.cmd
sshpk-sign
sshpk-sign.cmd
sshpk-verify
sshpk-verify.cmd
strip-indent
strip-indent.cmd
tsc
tsc.cmd
tsickle
tsickle.cmd
tslint
tslint.cmd
tsserver
tsserver.cmd
uglifyjs
uglifyjs.cmd
uuid
uuid.cmd
webpack
webpack.cmd
which
which.cmd

[imhoffd]

And can I see your ionic.config.json? (pasting your ionic info helps when chiming in for issues)

[mdodds93]

I am having the exact same problem. Ionic serve has been running smoothly (including directly after updating ionic-cli yesterday but after a system restart I am getting this message.

My ionic info

Ionic:

   ionic (Ionic CLI)  : 4.0.0 (C:\Users\matth\AppData\Roaming\npm\node_modules\ionic)
   Ionic Framework    : ionic-angular 3.9.2
   @ionic/app-scripts : 3.1.10

Cordova:

   cordova (Cordova CLI) : 8.0.0
   Cordova Platforms     : none

System:

   NodeJS : v8.11.2 (C:\Program Files\nodejs\node.exe)
   npm    : 5.6.0
   OS     : Windows 10

Environment:

   ANDROID_HOME : not set

[imhoffd]

The fact that it says "This package is required for ionic serve in ionic/angular 4 projects." has me believe something may be incorrect with the project configuration. When someone has a chance, please copy/paste the ionic.config.json file and the scripts within package.json so I can have more insight into the projects.

[Scombr0]

This happened to me after doing ionic cordova run android on a separate terminal tab (I use VSC on Windows 10).

The way to solve this (on my end), close VSC and open it again, then ionic serve works again. If I open another terminal tab and run the run, it bugs again.

[roytouw]

Same problem here after updating...

[imhoffd]

When someone has a chance, please copy/paste the ionic.config.json file and the scripts within package.json so I can have more insight into the projects.

[srobins259]

I am getting the same issue after updating to 4.0.1. I have tried installing @ionic/app-scripts and it has no effect. Restarted everything and still no progress.

[imhoffd]

I will literally never be able to fix this issue unless someone reads this comment and does what I ask:

When someone has a chance, please copy/paste the ionic.config.json file and the scripts within package.json so I can have more insight into the projects.

[devcenter]

this is my ionic.config.json

{
  "name": "Ionic-3-Green-Light",
  "integrations": {
    "cordova": {}
  },
  "type": "ionic-angular",
  "pro_id": "3fd41324"
}

and package.json

{
  "name": "ionicTemplate3",
  "author": "CSFORM",
  "version": "0.0.3",
  "homepage": "http://csform.com/",
  "private": true,
  "scripts": {
    "clean": "ionic-app-scripts clean",
    "build": "ionic-app-scripts build",
    "ionic:build": "ionic-app-scripts build",
    "ionic:serve": "ionic-app-scripts serve"
  },
  "dependencies": {
    "@agm/core": "1.0.0-beta.2",
    "@angular/common": "5.0.3",
    "@angular/compiler": "5.0.3",
    "@angular/compiler-cli": "5.0.3",
    "@angular/core": "5.0.3",
    "@angular/forms": "5.0.3",
    "@angular/http": "5.0.3",
    "@angular/platform-browser": "5.0.3",
    "@angular/platform-browser-dynamic": "5.0.3",
    "@ionic-native/barcode-scanner": "4.4.2",
    "@ionic-native/core": "4.4.0",
    "@ionic-native/firebase": "4.4.2",
    "@ionic-native/google-analytics": "4.4.2",
    "@ionic-native/splash-screen": "4.4.0",
    "@ionic-native/status-bar": "4.4.0",
    "@ionic/storage": "2.1.3",
    "angular2-google-maps": "0.17.0",
    "angularfire2": "5.0.0-rc.5-next",
    "cordova-android": "6.4.0",
    "cordova-plugin-compat": "^1.2.0",
    "cordova-plugin-console": "^1.1.0",
    "cordova-plugin-device": "^1.1.7",
    "cordova-plugin-firebase": "^0.1.25",
    "cordova-plugin-flashlight": "^3.2.0",
    "cordova-plugin-google-analytics": "^1.8.3",
    "cordova-plugin-spinner-dialog": "^1.3.1",
    "cordova-plugin-splashscreen": "^4.1.0",
    "cordova-plugin-statusbar": "^2.4.2",
    "cordova-plugin-vibration": "^2.1.6",
    "cordova-plugin-whitelist": "^1.3.3",
    "cordova-plugin-x-toast": "^2.6.2",
    "firebase": "4.6.2",
    "ion-affix": "1.1.0",
    "ionic-angular": "3.9.2",
    "ionic-plugin-keyboard": "^2.2.1",
    "ionicons": "3.0.0",
    "ngx-clipboard": "7.0.4",
    "phonegap-plugin-barcodescanner": "^7.1.2",
    "promise-polyfill": "6.0.2",
    "rxjs": "5.5.6",
    "sw-toolbox": "3.6.0",
    "zone.js": "0.8.18"
  },
  "devDependencies": {
    "@ionic/app-scripts": "3.1.8",
    "typescript": "2.4.0"
  },
  "cordovaPlugins": [
    "cordova-plugin-whitelist",
    "cordova-plugin-console",
    "cordova-plugin-statusbar",
    "cordova-plugin-device",
    "cordova-plugin-splashscreen",
    "ionic-plugin-keyboard"
  ],
  "cordovaPlatforms": [],
  "description": "Pre-designed UI elements for Ionic 3 framework..",
  "cordova": {
    "plugins": {
      "cordova-plugin-device": {},
      "cordova-plugin-firebase": {},
      "cordova-plugin-google-analytics": {},
      "cordova-plugin-splashscreen": {},
      "cordova-plugin-statusbar": {},
      "cordova-plugin-whitelist": {},
      "ionic-plugin-keyboard": {},
      "phonegap-plugin-barcodescanner": {
        "ANDROID_SUPPORT_V4_VERSION": "27.+"
      },
      "cordova-plugin-flashlight": {},
      "cordova-plugin-spinner-dialog": {},
      "cordova-plugin-vibration": {},
      "cordova-plugin-x-toast": {},
      "cordova-plugin-console": {}
    },
    "platforms": [
      "android"
    ]
  }
}

[devcenter]

I solved my problem by deleting node_modules and do npm install

[jagdishhulsure]

Ionic:

ionic (Ionic CLI) : 4.0.2 (/usr/local/lib/node_modules/ionic)
Ionic Framework : ionic-angular 3.9.2
@ionic/app-scripts : 3.1.5

Cordova:

cordova (Cordova CLI) : not installed
Cordova Platforms : not available

System:

ios-deploy : 2.0.0
NodeJS : v8.11.3 (/usr/local/bin/node)
npm : 6.2.0
OS : macOS High Sierra
Xcode : Xcode 9.4.1 Build version 9F2000

Environment:

ANDROID_HOME : not set

ionic serve --address=localhost --no-open

[WARN] Detected locally installed Ionic CLI, but it's too old--using global CLI.

ionic-app-scripts serve --address localhost --port 8100 --livereload-port 35729 --dev-logger-port 53703 --nobrowser

[ERROR] @ionic/app-scripts is required for ionic serve to work properly.

    Looks like @ionic/app-scripts isn't installed in this project.
    
    This package is required for ionic serve in ionic/angular 4 projects.

====================================================

When am trying to install @ionic/app-scripts using this command on mac (sudo npm install @ionic/app-scripts@latest --save-dev), once done . am running ionic serve and its throwing an error of--------------------------------------------------------------

** BUILD FAILED **

The following build commands failed:
Check dependencies
Write auxiliary files
(2 failures)
npm WARN @fimbul/bifrost@0.11.0 requires a peer of typescript@>= 2.7.1 || >= 3.0.0-dev || >= 3.0.0-insiders || 3.0.0-rc || >= 3.1.0-dev but none is installed. You must install peer dependencies yourself.
npm WARN @fimbul/ymir@0.11.0 requires a peer of typescript@>= 2.7.1 || >= 3.0.0-dev || >= 3.0.0-insiders || 3.0.0-rc || >= 3.1.0-dev but none is installed. You must install peer dependencies yourself.

npm ERR! code ELIFECYCLE
npm ERR! errno 65
npm ERR! ios-deploy@1.9.3 preinstall: ./src/scripts/check_reqs.js && xcodebuild
npm ERR! Exit status 65
npm ERR!
npm ERR! Failed at the ios-deploy@1.9.3 preinstall script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR! /Users/swarajyakamalamtadikonda/.npm/_logs/2018-07-31T12_53_40_861Z-debug.log

Simultaneously when am trying to install ios-deploy using this command "sudo npm install -g ios-deploy --unsafe-perm --allow-root" , while doing ionic serve am getting app-script error,

Please help me solve this issue.
Thank you in advance.