2019-06-03-NPM-Error

$ npm run serve

> ys-admin@0.1.0 serve D:\www\zcsys\manage
> vue-cli-service serve

 INFO  Starting development server...
 10% building 2/2 modules 0 active ERROR  TypeError: Cannot read property 'upgrade' of undefined
TypeError: Cannot read property 'upgrade' of undefined
    at Server.<anonymous> (D:\www\zcsys\manage\node_modules\webpack-dev-server\lib\Server.js:720:47)
    at Array.forEach (<anonymous>)
    at new Server (D:\www\zcsys\manage\node_modules\webpack-dev-server\lib\Server.js:719:22)
    at serve (D:\www\zcsys\manage\node_modules\@vue\cli-service\lib\commands\serve.js:138:20)
    at process._tickCallback (internal/process/next_tick.js:68:7)
    at Function.Module.runMain (internal/modules/cjs/loader.js:757:11)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:622:3)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! ys-admin@0.1.0 serve: `vue-cli-service serve`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the ys-admin@0.1.0 serve script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\Administrator\AppData\Roaming\npm-cache\_logs\2019-06-03T01_52_19_142Z-debug.log