title: Angular 8: "could not find implementation for builder" when running ng serve
body: <p>I just installed Angular 8. When I try to run a project with "ng serve --open" it gives me the following error:</p>
  
  <pre><code>
  Could not find the implementation for builder @angular-devkit/build-angular:dev-server
  Error: Could not  find the implementation for builder @angular-devkit/build-angular:dev-server
      at WorkspaceNodeModulesArchitectHost.resolveBuilder (C:\Users\manus\project\space-estate\webshop\frontend\client\node_modules\@angular\cli\node_modules\@angular-devkit\architect\node\node-modules-architect-host.js:49:19)
      at ServeCommand.initialize (C:\Users\manus\project\space-estate\webshop\frontend\client\node_modules\@angular\cli\models\architect-command.js:72:63)
      at process._tickCallback (internal/process/next_tick.js:68:7)
      at Function.Module.runMain (internal/modules/cjs/loader.js:744:11)
      at startup (internal/bootstrap/node.js:285:19)
      at bootstrapNodeJSCore (internal/bootstrap/node.js:739:3)
  
  </code></pre>
  
  <p>when I check the versions it gives me the following:</p>
  
  <pre><code>Angular CLI: 8.0.1
  Node: 10.13.0
  OS: win32 x64
  Angular: 8.0.0
  ... animations, common, compiler, compiler-cli, core, forms
  ... language-service, platform-browser, platform-browser-dynamic
  ... router
  
  Package                           Version
  -----------------------------------------------------------
  @angular-devkit/architect         0.13.9
  @angular-devkit/build-angular     0.13.9
  @angular-devkit/build-optimizer   0.13.9
  @angular-devkit/build-webpack     0.13.9
  @angular-devkit/core              8.0.1
  @angular-devkit/schematics        8.0.1 (cli-only)
  @ngtools/webpack                  7.3.9
  @schematics/angular               8.0.1 (cli-only)
  @schematics/update                0.800.1 (cli-only)
  rxjs                              6.5.2
  typescript                        3.4.5
  webpack                           4.29.0
  </code></pre>