Error "Unexpected end of multipart data" in busboy file upload

I am using connect-busboy to upload file in node/express app.The problem is sometimes it works(file get uploaded succsesfully) and sometimes i get error Unexpected end of multipart data and the application crash.What could be the cause of this error? Also any help on how to debug this will be appreciated. I am using node version 5 and connect-busboy": "0.2.14"Thank you in advance

router.route('/images')    
  .post (function(req, res) {

  var fstream;
  req.busboy.on('file', function (fieldname, file, filename) {

    fstream = fs.createWriteStream(__dirname + '/public/img/'+ filename);
    file.pipe(fstream);
    file.on('end', function() {
      console.log('File [' + fieldname + '] Finished sucessfully');
     });
    fstream.on('error',function(err){
      console.log('fstream error' + err);
      file.unpipe();
    });
    fstream.on('close', function () {
    res.status(200);
    res.json({ message: 'File uploaded' });

    });
});
req.pipe(req.busboy);

});

This is the error i am getting

throw er; // Unhandled 'error' event
: Error: Unexpected end of multipart data
2017-05-07T20:28:27.599826+00:00 app[web.1]:     at 
/app/node_modules/busboy/node_modules/dicer/lib/Dicer.js:62:28

via sparks