title: Job name "..getProjectMetadata" does not exist
body: <p>I updated my angular to v9 and when I try to go back in v8, I receive this error.
  I have already tried the following:</p>
  
  <ul>
  <li>uninstall -global angular/cli</li>
  <li>uninstall angular/cli</li>
  <li>go back to my last package.json</li>
  <li>delete node_module folder</li>
  <li>delete repo</li>
  </ul>
  
  <p>This error continues to show.</p>
  
  <p>My stacktrace is :</p>
  
  <pre><code>An unhandled exception occurred: Job name "..getProjectMetadata" does not exist.
  See angular-errors.log for further details.
  </code></pre>
  
  <p>angular-errors.log :</p>
  
  <pre><code>[error] Error: Job name "..getProjectMetadata" does not exist.
      at Observable._subscribe (/Front/node_modules/@angular-devkit/core/src/experimental/jobs/simple-scheduler.js:350:23)
      at Observable._trySubscribe (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Observable.js:44:25)
      at Observable.subscribe (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Observable.js:30:22)
      at /Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/util/subscribeTo.js:22:31
      at Object.subscribeToResult (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/util/subscribeToResult.js:10:45)
      at SwitchMapSubscriber._innerSub (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/switchMap.js:65:54)
      at SwitchMapSubscriber._next (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/switchMap.js:55:14)
      at SwitchMapSubscriber.Subscriber.next (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Subscriber.js:66:18)
      at SwitchMapSubscriber.notifyNext (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/switchMap.js:86:26)
      at InnerSubscriber._next (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/InnerSubscriber.js:28:21)
      at InnerSubscriber.Subscriber.next (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Subscriber.js:66:18)
      at /Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/util/subscribeTo.js:17:28
      at Object.subscribeToResult (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/util/subscribeToResult.js:10:45)
      at SwitchMapSubscriber._innerSub (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/switchMap.js:65:54)
      at SwitchMapSubscriber._next (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/operators/switchMap.js:55:14)
      at SwitchMapSubscriber.Subscriber.next (/Front/node_modules/@angular-devkit/core/node_modules/rxjs/internal/Subscriber.js:66:18)
  </code></pre>
  
  <p>ng --version :</p>
  
  <pre><code>Angular CLI: 8.3.18
  Node: 12.15.0
  OS: darwin x64
  Angular: 8.2.13
  ... animations, common, compiler, compiler-cli, core, forms
  ... language-service, platform-browser, platform-browser-dynamic
  ... router
  
  Package                           Version
  -----------------------------------------------------------
  @angular-devkit/architect         0.803.18
  @angular-devkit/build-angular     0.900.1
  @angular-devkit/build-optimizer   0.900.1
  @angular-devkit/build-webpack     0.900.1
  @angular-devkit/core              8.3.18
  @angular-devkit/schematics        8.3.18
  @angular/cdk                      8.2.3
  @angular/cli                      8.3.18
  @angular/material                 8.2.3
  @ngtools/webpack                  9.0.1
  @schematics/angular               8.3.18
  @schematics/update                0.803.18
  rxjs                              6.5.3
  typescript                        3.5.3
  webpack                           4.41.2
  </code></pre>