The NPM script 'start' exited without indicating that the Angular CLI was listening for requests

问题

I'm attempting to start an .NET Core 2/Angular 6 SPA. I created an Angular 5 Application using "dotnet new angular" then proceeded to upgrade using this guide from angular.io. Once I finished the upgrade I tried to run the application using "dotnet run" and I get an ugly error page with the error:

An unhandled exception occurred while processing the request.

AggregateException: One or more errors occurred. (One or more errors occurred. (The NPM script 'start' exited without indicating that the Angular CLI was listening for requests. The error output was: Unknown option: '--extractCss'

InvalidOperationException: The NPM script 'start' exited without indicating that the Angular CLI was listening for requests. The error output was: Unknown option: '--extractCss'

Thinking perhaps I missed a step during the upgrade, I tried a second time and got the same error.

Here are the steps I took after creating the app:

npm install -g @angular/cli
npm install @angular/cli
ng update @angular/cli
ng update @angular/core
npm install --save @angular/material @angular/cdk @angular/animations hammerjs 
npm install -g rxjs-tslint
rxjs-5-to-6-migrate -p src/tsconfig.app.json

I'm running Node version 9.4.0 and .Net Core 2.1.200 on Windows 10 (1703) Enterprise.

Any ideas on how to fix this? Here is a full stack trace:

 ---> System.IO.EndOfStreamException: Attempted to read past the end of the stream.
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.SpaServices.AngularCli.AngularCliMiddleware.<StartAngularCliServerAsync>d__3.MoveNext()
   --- End of inner exception stack trace ---
   at Microsoft.AspNetCore.SpaServices.AngularCli.AngularCliMiddleware.<StartAngularCliServerAsync>d__3.MoveNext()
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at Microsoft.AspNetCore.SpaServices.AngularCli.AngularCliMiddleware.<>c.<Attach>b__2_0(Task`1 task)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at Microsoft.AspNetCore.SpaServices.Extensions.Util.TaskTimeoutExtensions.<WithTimeout>d__1`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.SpaServices.Extensions.Proxy.SpaProxy.<PerformProxyRequest>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Builder.SpaProxyingExtensions.<>c__DisplayClass2_0.<<UseProxyToSpaDevelopmentServer>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.<Invoke>d__7.MoveNext()
---> (Inner Exception #0) System.AggregateException: One or more errors occurred. (The NPM script 'start' exited without indicating that the Angular CLI was listening for requests. The error output was: Unknown option: '--extractCss'

) ---> System.InvalidOperationException: The NPM script 'start' exited without indicating that the Angular CLI was listening for requests. The error output was: Unknown option: '--extractCss'

 ---> System.IO.EndOfStreamException: Attempted to read past the end of the stream.
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.SpaServices.AngularCli.AngularCliMiddleware.<StartAngularCliServerAsync>d__3.MoveNext()
   --- End of inner exception stack trace ---
   at Microsoft.AspNetCore.SpaServices.AngularCli.AngularCliMiddleware.<StartAngularCliServerAsync>d__3.MoveNext()
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at Microsoft.AspNetCore.SpaServices.AngularCli.AngularCliMiddleware.<>c.<Attach>b__2_0(Task`1 task)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot)
---> (Inner Exception #0) System.InvalidOperationException: The NPM script 'start' exited without indicating that the Angular CLI was listening for requests. The error output was: Unknown option: '--extractCss'

 ---> System.IO.EndOfStreamException: Attempted to read past the end of the stream.
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.SpaServices.AngularCli.AngularCliMiddleware.<StartAngularCliServerAsync>d__3.MoveNext()
   --- End of inner exception stack trace ---
   at Microsoft.AspNetCore.SpaServices.AngularCli.AngularCliMiddleware.<StartAngularCliServerAsync>d__3.MoveNext()<---
<---

回答1:

For me this and the followings are solved the issue: https://github.com/angular/angular-cli/issues/10666

And also you need to edit your package.json file and remove the --extractCss parameter from the start and build property. from:

"scripts": {
    "ng": "ng",
    "start": "ng serve --extract-css",
    "build": "ng build --extract-css",

to:

"scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",

回答2:

Try to do the following

Open a Powershell
Navigate to the clientapp directory
Run “npm audit fix”

It worked for me

回答3:

The problem bugs me for a couple days too. Now finally get a way around. Apparently, Visual Studio tries to launch Angular CLI server for us automatically along with the ASP.Net core process. For this instance, it failed.

So according to Microsoft Doc here, we can start Angular CLI server manually.

navigate to the 'ClientApp' folder, and issue:

ng serve

to start server from the console.
In 'Startup.cs' file, replace

spa.UseAngularCliServer(..)

with

spa.UseProxyToSpaDevelopmentServer("http://localhost:4200");

F5 to start ASP.Net Core project as we normally do.

This way you can continue debugging the application.

回答4:

If the above solution does not work, you can try the following which worked for me.

Scenario: Transferred working VS 2017 solution: core web api & angular spa projects to newly installed pc; gave me the above error.

Solution: After installing node.js workloads via visual studio installer, node.js for windows (https://nodejs.org/en/download/) and the necessary windows features for IIS; I was back on track.

The main installation is the node.js for visual studio and windows (which has npm included), had to install both for it to work. Probably the paths config for command prompt....

回答5:

Both Joe and Jays solutions work. To use the default template configuration without code changes you just need to install node.js for windows as Jay stated above and then restart VS. https://nodejs.org/en/download/

An excellent tutorial on creating, configuring and deploying Core Angular projects with vs and vscode here . Includes IIS setup as well. https://www.codeproject.com/Articles/1250961/Deploying-an-Angular-Application-with-ASP-NET-Core

回答6:

In my case, I've removed following application setting from the azure web app and site was started working.

Key: ASPNETCORE_ENVIRONMENT Value: Development

Spent several days to figure out the issue :)

来源：https://stackoverflow.com/questions/50221618/the-npm-script-start-exited-without-indicating-that-the-angular-cli-was-listen

标签

angular

.net-core

angular6