C:\WINDOWS\system32>npm install vue-cli -g
npm WARN deprecated coffee-script@1.12.7: CoffeeScript on NPM has moved to "coffeescript" (no hyphen)
npm WARN deprecated request@2.88.2: request has been deprecated, see https://github.com/request/request/issues/3142
npm WARN deprecated duplexer3@0.1.4: Sadly, duplexer3 is
 
 no longer with us. It will be missed.
npm WARN rm not removing C:\Program Files\nodejs\vue.ps1 as it wasn't installed by C:\Program Files\nodejs\node_modules\vue-cli
npm WARN rm not removing C:\Program Files\nodejs\vue.cmd as it wasn't installed by C:\Program Files\nodejs\node_modules\vue-cli
npm WARN rm not removing C:\Program Files\nodejs\vue as
 
 it wasn't installed by C:\Program Files\nodejs\node_modules\vue-cli
C:\Program Files\nodejs\vue-init -> C:\Program Files\nodejs\node_modules\vue-cli\bin\vue-init
C:\Program Files\nodejs\vue-list -> C:\Program Files\nodejs\node_modules\vue-cli\bin\vue-list
npm ERR! code EEXIST
npm ERR! path C:\Program Files\nodejs\node_modules\vue-cli\bin\vue
npm ERR
 
! dest C:\Program Files\nodejs\vue.cmd
npm ERR! EEXIST: file already exists, cmd shim 'C:\Program Files\nodejs\node_modules\vue-cli\bin\vue' -> 'C:\Program Files\nodejs\vue.cmd'
npm ERR! File exists: C:\Program Files\nodejs\vue.cmd
npm ERR! Remove the existing file and try again, or run npm
npm ERR! with --force to overwrite files recklessly.

npm ERR! A complete log of this run can be found in:
npm ERR! C:\Users\zwenliao\.npm\_logs\2020-07-06T03_31_36_024Z-debug.log

方案1：暴力解決，直接輸入指令

C:\WINDOWS\system32> npm install vue-cli -g  --force

方案2：

錯誤是C:\Program Files\nodejs\vue.cmd檔案已經存在 需要刪除

方案2參考連結