title: react-native start report: Error: UNKNOWN: unknown error, open ...\.babel.json
body: <p>I have a RN developing environment on Windows 7. It works fine until yesterday it suddenly reports error after I run "react-native" start.
  The error Message:</p>
  
  <pre><code>[2016-12-26 09:58:17]         HMR Server listening on /hot
  
  React packager ready.
  
  fs.js:557
    return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
                   ^
  
  Error: UNKNOWN: unknown error, open 'C:\Users\xitao\.babel.json'
      at Object.fs.openSync (fs.js:557:18)
      at Object.fs.writeFileSync (fs.js:1222:33)
      at save (C:\RN\LearnRN\node_modules\babel-register\lib\cache.js:45:16)
      at _combinedTickCallback (internal/process/next_tick.js:67:7)
      at process._tickCallback (internal/process/next_tick.js:98:9)
  fs.js:557
    return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
                   ^
  
  Error: UNKNOWN: unknown error, open 'C:\Users\xitao\.babel.json'
      at Object.fs.openSync (fs.js:557:18)
      at Object.fs.writeFileSync (fs.js:1222:33)
      at save (C:\RN\LearnRN\node_modules\babel-register\lib\cache.js:45:16)
      at _combinedTickCallback (internal/process/next_tick.js:67:7)
      at process._tickCallback (internal/process/next_tick.js:98:9)
  fs.js:557
    return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
                   ^
  
  Error: UNKNOWN: unknown error, open 'C:\Users\xitao\.babel.json'
      at Object.fs.openSync (fs.js:557:18)
      at Object.fs.writeFileSync (fs.js:1222:33)
      at save (C:\RN\LearnRN\node_modules\babel-register\lib\cache.js:45:16)
      at _combinedTickCallback (internal/process/next_tick.js:67:7)
      at process._tickCallback (internal/process/next_tick.js:98:9)
  </code></pre>
  
  <p>I google the error, no luck.
  I delete the .babel.json, the error stiil comes out.
  I reinit a new project, still the same. I uninstall node.js and python, then install them again follow the "Getting Started" on RN mainpage, still the same.
  I install react-native-cli 2.0.1 and 1.3.0, still the same.</p>
  
  <p>It seems the RN project works even with the error. But you never know when the error will hurt my project.</p>