为什么我的 angular 8 项目在安装 angular 10 cli 后没有启动？

Question

I was working on anagular 8 project on my computer. But now need to install angular 10 t run another project.

So I have installed new version as globally: npm install -g @angular/cli

And the new angular 10 project works now, but angular 8 project does not start. It throws an error while starting.

An unhandled exception occurred: Cannot find module '@angular-devkit/build-angular/package.json' Require stack:

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\node_modules@angular-devkit\architect\node\node-modules-architect-host.js

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\node_modules@angular-devkit\architect\node\index.js

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\models\architect-command.js

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\commands\serve-impl.js

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\node_modules@angular-devkit\schematics\tools\export-ref.js

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\node_modules@angular-devkit\schematics\tools\index.js

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\utilities\json-schema.js

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\models\command-runner.js

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\lib\cli\index.js

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\lib\init.js

• C:\Users\Mm\AppData\Roaming\npm\node_modules@angular\cli\bin\ng See "C:\Users\Mm\AppData\Local\Temp\ng-mhNKKl\angular-errors.log" for further details.

My system versions are:

• npm: '6.14.6'
• Node.js v12.18.3
• Angular CLI: 10.0.8

Answer 1

use this command in cmd

npm install --save-dev @angular-devkit/build-angular

Try this also

npm update

Answer 2

You should not upgrade angular directly to version 10, if you are behind several versions. In your case you are at version 8 but you are going to upgrade to version 10.

In such scenario you have to upgrade to version 9 before 10.

You can find official upgrading guide docs for the same here .