title: How to fix "webpack Dev Server Invalid Options" in Vuejs
body: <p>I am using <code>@vue/cli v3.7.0</code> and I created a project by <code>vue create myapp</code> with Babel + Router + node-sass and my project got installed successfully</p>
  
  <p>But when I ran npm run serve (in the project directory) I got following error:</p>
  
  <pre><code>
   INFO  Starting development server...
   ERROR  ValidationError: webpack Dev Server Invalid Options
  
  options.clientLogLevel should be {String} and equal to one of the allowed values
  
   [ 'info', 'warn', 'error', 'debug', 'trace', 'silent' ]
  
   (https://webpack.js.org/configuration/dev-server/#devserverclientloglevel)
  
  ValidationError: webpack Dev Server Invalid Options
  
  options.clientLogLevel should be {String} and equal to one of the allowed values
  
   [ 'info', 'warn', 'error', 'debug', 'trace', 'silent' ]
  
   (https://webpack.js.org/configuration/dev-server/#devserverclientloglevel)
  
      at validateOptions (C:\Users\Dell\Desktop\myapp\node_modules\webpack-dev-server\node_modules\schema-utils\src\validateOptions.js:32:11)
      at new Server (C:\Users\Dell\Desktop\myapp\node_modules\webpack-dev-server\lib\Server.js:71:5)
      at serve (C:\Users\Dell\Desktop\myapp\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! myapp@0.1.0 serve: `vue-cli-service serve`
  npm ERR! Exit status 1
  npm ERR! 
  npm ERR! Failed at the myapp@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\Dell\AppData\Roaming\npm-cache\_logs\2019-05-17T19_40_14_984Z-debug.log
  </code></pre>
  
  <p>I tried <code>npm cache clean -f</code>, reinstallation of VueJS, recreation of project but nothing worked :(</p>
  
  <p>I expect my <code>npm run serve</code> work!</p>