title: Error: EPERM: operation not permitted
body: <p>at the moment I try to develop an ionic-app with Webstorm. 
  But gulp is making some troubles.</p>
  
  <p>Installed Packages:</p>
  
  <pre><code>"gulp": "^3.5.6",
  "gulp-concat": "^2.2.0",
  "gulp-minify-css": "^0.3.0",
  "gulp-rename": "^1.2.0",
  "gulp-sass": "^2.1.0"
  </code></pre>
  
  <p>But  when I type <code>gulp</code> or 'ionic serve' in the terminal and run it I get the following error message:</p>
  
  <pre><code>[18:36:00] Using gulpfile ~\app\gulpfile.js
  [18:36:00] Starting 'sass'...
  stream.js:74
        throw er; // Unhandled stream error in pipe.
        ^
  
  Error: EPERM: operation not permitted, open 'C:\Users\Chef\app\www\css\ionic.app.css'
      at Error (native)
  </code></pre>
  
  <p>I am using Windows10x64.</p>
  
  <p>I tried the following things but none of it works:</p>
  
  <ul>
  <li>Run as administrator</li>
  <li>Turn off Avira</li>
  <li>Recreate the file</li>
  <li>Reinstalled gulp</li>
  </ul>
  
  <p>Any advice?</p>
  
  <p>Thanks in advance!</p>