- Go to /system/etc/permissions/platform.xml
 - Find android.permission.WRITE_EXTERNAL_STORAGE and android.permission.WRITE_MEDIA_STORAGE lines. These are XML sections. 
   You need to make them look exactly like the strings below: 
 <permission name="android.permission.WRITE_EXTERNAL_STORAGE" >
      <group gid="sdcard_r" />
      <group gid="sdcard_rw" />
      <group gid="media_rw" />
  </permission>
  <permission name="android.permission.WRITE_MEDIA_STORAGE" >
      <group gid="sdcard_rw" />
      <group gid="media_rw" />
 </permission>