ng-serve is not working - Could not find module "@angular-devkit/build-angular"

[DineshChopra]

Versions

ng : 6.0.0
node : v8.9.0
npm : 6.0.0
Operating System : macOS

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Repro steps

• Step 1
• Step 2
• Step 3

I have created new project with angular-cli.
ng new testapp
cd testapp
npm install
ng serve

ng serve is not working. I found following error

Could not find module "@angular-devkit/build-angular" from "/Users/dic/workspace/projects/carpool".
Error: Could not find module "@angular-devkit/build-angular" from "/Users/dic/workspace/projects/carpool".
    at Object.resolve (/usr/local/lib/node_modules/@angular/cli/node_modules/@angular-devkit/core/node/resolve.js:141:11)
    at Observable.rxjs_1.Observable [as _subscribe] (/usr/local/lib/node_modules/@angular/cli/node_modules/@angular-devkit/architect/src/architect.js:132:40)
    at Observable.subscribe (/usr/local/lib/node_modules/@angular/cli/node_modules/rxjs/internal/Observable.js:162:69)
    at DoOperator.call (/usr/local/lib/node_modules/@angular/cli/node_modules/rxjs/internal/operators/tap.js:71:23)
    at Observable.subscribe (/usr/local/lib/node_modules/@angular/cli/node_modules/rxjs/internal/Observable.js:159:22)
    at /usr/local/lib/node_modules/@angular/cli/node_modules/rxjs/internal/util/subscribeTo.js:22:31
    at Object.subscribeToResult (/usr/local/lib/node_modules/@angular/cli/node_modules/rxjs/internal/util/subscribeToResult.js:7:45)
    at MergeMapSubscriber._innerSub (/usr/local/lib/node_modules/@angular/cli/node_modules/rxjs/internal/operators/mergeMap.js:132:38)
    at MergeMapSubscriber._tryNext (/usr/local/lib/node_modules/@angular/cli/node_modules/rxjs/internal/operators/mergeMap.js:129:14)
    at MergeMapSubscriber._next (/usr/local/lib/node_modules/@angular/cli/node_modules/rxjs/internal/operators/mergeMap.js:112:18)

dic@dic.local [~/workspace/projects/carpool]$ ng --version

So request you to please help me to resolve that issue

Observed behavior

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Desired behavior

Mention any other details that might be useful (optional)

[tomash970]

Same here:

Angular CLI: 6.0.0
Node: 10.0.0
Ubuntu 16.04

Could not find module "@angular-devkit/build-angular" from "/opt/lampp/htdocs/newp".
Error: Could not find module "@angular-devkit/build-angular" from "/opt/lampp/htdocs/newp".
at Object.resolve (/opt/lampp/htdocs/newp/node_modules/@angular-devkit/core/node/resolve.js:141:11)
at Observable.rxjs_1.Observable [as _subscribe] (/opt/lampp/htdocs/newp/node_modules/@angular-devkit/architect/src/architect.js:132:40)
at Observable.subscribe (/opt/lampp/htdocs/newp/node_modules/rxjs/internal/Observable.js:162:69)
at DoOperator.call (/opt/lampp/htdocs/newp/node_modules/rxjs/internal/operators/tap.js:71:23)
at Observable.subscribe (/opt/lampp/htdocs/newp/node_modules/rxjs/internal/Observable.js:159:22)
at /opt/lampp/htdocs/newp/node_modules/rxjs/internal/util/subscribeTo.js:22:31
at Object.subscribeToResult (/opt/lampp/htdocs/newp/node_modules/rxjs/internal/util/subscribeToResult.js:7:45)
at MergeMapSubscriber._innerSub (/opt/lampp/htdocs/newp/node_modules/rxjs/internal/operators/mergeMap.js:132:38)
at MergeMapSubscriber._tryNext (/opt/lampp/htdocs/newp/node_modules/rxjs/internal/operators/mergeMap.js:129:14)
at MergeMapSubscriber._next (/opt/lampp/htdocs/newp/node_modules/rxjs/internal/operators/mergeMap.js:112:18)

[DineshChopra]

I remove my repo.
Create new project again ng new testapp
cd testapp
npm install
ng serve

Its working for me know, but don't know why its not working earlier. Either its a problem of angular-cli or its a problem of my system.

It waste my 3 hours. So please clarify what exactly we have to do when we face that kind of issue.

[ahnpnl]

I encountered this issue when use ng update to upgrade from 5 to 6. After successfully upgraded, the app couldn't start

[Blair2004]

Same right here... but have seen that the last CLI command to update :
rxjs-5-to-6-migrate -p src/tsconfig.app.json

doesn't work as expected. Indeed that throw an error :

Running the automatic migrations. Please, be patient and wait until the execution completes.
'C:\Users\Blair' n'est pas reconnu en tant que commande interne
ou externe, un programme ex�cutable ou un fichier de commandes.
child_process.js:644
    throw err;
    ^

Error: Command failed: C:\Users\Blair Jersyer\AppData\Roaming\npm\node_modules\rxjs-tslint\node_modules\.bin\tslint -c C:\Users\Blair Jersyer\AppData\Roaming\npm\node_modules\rxjs-tslint\rxjs-5-to-6-migrate.json -p src/tsconfig.app.json --fix

Should probably mention that, my Windows username has a space between "Blair Jersyer", does it have anything to do with ?

[Blair2004]

@DineshChopra i've finally made this npm install @angular-devkit/build-angular and it worked. I'm wondering it sould be within the dev deps or not ?

[casoetan]

@Blair2004 it should be in dev deps (@angular-devkit).

[superstator]

Was running into this, and it ended up being a mismatch between the version of rxjs in package-lock.json and my installed version. Updated all my machines to 6.1 with npm i -g rxjs and am able to build and run again. Supremely unhelpful error message, though...

[kylebradshaw]

For myself, during an upgrade from an NG5 app, when I hit this issue I essentially deleted my package-json.lock file and removed my node_modules dir and then npm i again and it worked. @superstator was right though the issue is in the package-lock.json file if you're upgrading from NG5

[shauvet]

You can try rm -rf node_modules then reinstall npm i. This works for me.

[superstator]

FWIW, I wasn't upgrading an old project. I started a brand new project over the weekend on one machine (Win 10) and then checked it out and attempted to run on another (MacOS High Sierra). Both have brand new node installs, and @angular/cli 6.0, I just somehow ended up with rxjs 6.0 on one and 6.1 on the other, and the build was apparently flummoxed by the mismatched version.

I saw the crash both ways, too - the project was created with a reference to rxjs 6.0, and this crashed when I checked it out on the machine with rxjs 6.1. Somehow I managed to thrash around and upgrade the project without realizing it, and it started working on the 6.1 machine. Then I moved back to the original machine with 6.0 and it started crashing again, and I had to go take a break before I threw something out the window. I finally figured it out by nuking the entire project folder on the 6.0 machine, recreating from scratch with ng new, verifying that ran OK, and then stepping through the git diff until I narrowed it down to the rxjs version.

[krishragu12395]

I think RxJS v6 has major changes from v5, v6 brings backwards compatibility package rxjs-compat that will keep your applications working, but you should refactor TypeScript code so that it doesn't depend on rxjs-compat. For the same run following
npm install -g rxjs-tslint,
rxjs-5-to-6-migrate -p src/tsconfig.app.json
npm uninstall rxjs-compat for.
Then npm install --force for bypass the node-sass issues. You'll have a broken node-sass install but everything else will still work.
Now my existing angular 5 app is upgraded to angular 6.

[JoA-MoS]

I had the same issue I found that running the command to create the new project in PowerShell rather than Git Bash seemed to solve the problem for some reason.

[ken107]

I looked inside node_modules and apparently only dependencies are installed, not devDependencies. With the new NPM, we need to explicitly get the devDependencies:

npm i --only=dev

[sliceofbytes]

I recently helped someone debug this issue, problem ended up being an old yarn install he had forgotten about.

I had him uninstall yarn completely and attempt to ng new test-app

the next error made the problem obvious.

'yarn' is not recognized as an internal or external command, operable program or batch file. Package install failed, see above.

Had him set angular-cli package manager back to npm.

ng config -g cli.packageManager npm

and everything worked. Hope this helps someone.