Useful or not, from you.
angular-cli Cannot find module '@angular/compiler-cli/ngcc'

my package.json

{ "name": "new-course", "version": "0.0.0", "scripts": { "ng": "ng", "start": "ng serve", "build": "ng build", "test": "ng test", "lint": "ng lint", "e2e": "ng e2e" }, "private": true, "dependencies": { "@angular/animations": "^6.1.0", "@angular/common": "^6.1.0", "@angular/compiler": "^6.1.0", "@angular/core": "^6.1.0", "@angular/forms": "^6.1.0", "@angular/http": "^6.1.0", "@angular/platform-browser": "^6.1.0", "@angular/platform-browser-dynamic": "^6.1.0", "@angular/router": "^6.1.0", "core-js": "^2.5.4", "rxjs": "~6.2.0", "zone.js": "~0.8.26" }, "devDependencies": { "@angular-devkit/build-angular": "^0.803.21", "@angular/cli": "~8.3.21", "@angular/compiler-cli": "^6.1.0", "@angular/language-service": "^6.1.0", "@types/jasmine": "~2.8.8", "@types/jasminewd2": "~2.0.3", "@types/node": "~8.9.4", "codelyzer": "~4.3.0", "jasmine-core": "~2.99.1", "jasmine-spec-reporter": "~4.2.1", "karma": "~3.0.0", "karma-chrome-launcher": "~2.2.0", "karma-coverage-istanbul-reporter": "~2.0.1", "karma-jasmine": "~1.1.2", "karma-jasmine-html-reporter": "^0.2.2", "protractor": "~5.4.0", "ts-node": "~7.0.0", "tslint": "~5.11.0", "typescript": "~2.9.2" } }

my angular version Angular CLI: 8.3.21 Node: 13.5.0 OS: linux x64 Angular: 6.1.10 ... animations, common, compiler, compiler-cli, core, forms ... http, language-service, platform-browser ... platform-browser-dynamic, router

Package Version

@angular-devkit/architect 0.803.21 @angular-devkit/build-angular 0.803.21 @angular-devkit/build-optimizer 0.803.21 @angular-devkit/build-webpack 0.803.21 @angular-devkit/core 8.3.21 @angular-devkit/schematics 8.3.21 @angular/cli 8.3.21 @ngtools/webpack 8.3.21 @schematics/angular 8.3.21 @schematics/update 0.803.21 rxjs 6.2.2 typescript 2.9.2 webpack 4.39.2

gives following error on ng serve

An unhandled exception occurred: Cannot find module '@angular/compiler-cli/ngcc' Require stack:

  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@ngtools/webpack/src/ngcc_processor.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@ngtools/webpack/src/angular_compiler_plugin.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@ngtools/webpack/src/index.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular-devkit/build-angular/src/angular-cli-files/models/webpack-configs/typescript.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular-devkit/build-angular/src/angular-cli-files/models/webpack-configs/index.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular-devkit/build-angular/src/browser/index.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular-devkit/build-angular/src/dev-server/index.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular/cli/node_modules/@angular-devkit/architect/node/node-modules-architect-host.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular/cli/node_modules/@angular-devkit/architect/node/index.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular/cli/models/architect-command.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular/cli/commands/serve-impl.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular-devkit/schematics/tools/export-ref.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular-devkit/schematics/tools/index.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular/cli/utilities/json-schema.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular/cli/models/command-runner.js
  • /home/ruyam/projects/secretprojects/courseman/newCourse/node_modules/@angular/cli/lib/cli/index.js
  • /usr/lib/node_modules/@angular/cli/lib/init.js
  • /usr/lib/node_modules/@angular/cli/bin/ng See "/tmp/ng-cmygeo/angular-errors.log" for further details.
That's a useful answer
Without any help

Angular CLI 8 is only compatible with Angular version 8.

For more info on how to update see: http://update.angular.io