android-get nullpointerexception when try to access video on external storage(sdcard)

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http://stackoverflow.com – In my app, I have a video upload option which allows user to upload the video. everything works fine except when user tried to pick a video from external storage. the app will just crash and give NullPointerException. Can someone please explain why? how come the function works fine when user choose video from gallery or phone storage but not external storage? this is the error message I got java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=2, result=-1, data=Intent { act=file:///mnt/sdcard/Android/data/com.dropbox.android/files/scratch/VIDEO0010.mp4 dat=file: (HowTos)