title: .NET core 3.1 - Angular 9 - The Angular CLI process did not start listening for requests within the timeout period of 0 seconds
body: <p><strong>[ carefull that this question has already been asked, but none of the suggestions appear to work and also the timeout is 0s in my case ]</strong></p>
  
  <p><strong>problem:</strong></p>
  
  <p>I can't have a .NET core / angular application working on my computer</p>
  
  <p>It works at home (Win 7, VS 2019 community), but <strong>not on my work pc (Win10, VS 2019 pro)</strong></p>
  
  <p>Chrome/FFox keep loading the index page, then I get a timeout</p>
  
  <p><strong>error:</strong></p>
  
  <pre><code>Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: Error: An unhandled exception has occurred while executing the request.
  
  System.TimeoutException: The Angular CLI process did not start listening for requests within the timeout period of 0 seconds. Check the log output for error information.
     at Microsoft.AspNetCore.SpaServices.Extensions.Util.TaskTimeoutExtensions.WithTimeout[T](Task`1 task, TimeSpan timeoutDelay, String message)
     at Microsoft.AspNetCore.SpaServices.Extensions.Proxy.SpaProxy.PerformProxyRequest(HttpContext context, HttpClient httpClient, Task`1 baseUriTask, CancellationToken applicationStoppingToken, Boolean proxy404s)
     at Microsoft.AspNetCore.Builder.SpaProxyingExtensions.&lt;&gt;c__DisplayClass2_0.&lt;&lt;UseProxyToSpaDevelopmentServer&gt;b__0&gt;d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
  </code></pre>
  
  <p><strong>expected behaviour:</strong></p>
  
  <p>the angular app should display in the browser</p>
  
  <p><strong>what I tried :</strong></p>
  
  <p>I updated VS many times</p>
  
  <p>I upgraded angular twice (from 8.0 -> 8.2 -> 9.1.9)</p>
  
  <pre><code>ng update @angular/core@8 @angular/cli@8
  ng update @angular/core@9 @angular/cli@9
  </code></pre>
  
  <p>I tried adding a timeout</p>
  
  <pre><code>spa.Options.StartupTimeout = new TimeSpan(0, 0, 80);
  spa.UseAngularCliServer(npmScript: "start");
  </code></pre>
  
  <p>I tried replacing the start command in package.json</p>
  
  <pre><code>"start": "echo Starting... &amp;&amp; ng serve",
  </code></pre>
  
  <p>I added a progress to the angular.json for the build to see when the app was available</p>
  
  <pre><code>"browserTarget": "WebApplication1:build",
  "progress": true
  </code></pre>
  
  <p>I see IISExpress listening on the port</p>
  
  <pre><code>C:\WINDOWS\system32&gt;netstat -afo | grep 22710
    TCP    0.0.0.0:22710          ########################.net:0  LISTENING       4
  </code></pre>
  
  <p>I tried to change the port to another one in launchSettings.json</p>
  
  <pre><code>"applicationUrl": "http://localhost:8081",
  </code></pre>
  
  <p>I also tried doing this, but the port gets overriden by some random port that seems unaccessible</p>
  
  <pre><code>ng serve --port 8081
  </code></pre>
  
  <p>I can run the angular app on the command line </p>
  
  <ul>
  <li><p>using <strong>ng serve</strong> , the angular app shows up but there is no backend services</p></li>
  <li><p>using <strong>dotnet run</strong>, I get the same timeout issue</p></li>
  </ul>
  
  <p><strong>overall:</strong></p>
  
  <p>it seems like .NET core framework is unable to contact angular cli somehow</p>
  
  <p>any idea what I could check or change to make this work ?</p>
  
  <p><strong>thanks for the time you'll spend on this one</strong></p>