MultipartRequest.calculateContentLength error

I am trying to make a multipart upload withsome binary data. However, I am getting a very strange error which I have never encountered. Here is my code

MultipartRequest request = new MultipartRequest();
            request.setPost(true);
            request.setUrl(URL+"/agenci/worker/addWorker/");
            ..,
            request.addData("photoFile", dir  + "user.jpg", "image/jpeg");

I get this exception at runtime

[EDT] 0:0:0,1 - Exception: java.lang.NullPointerException - null
    at com.codename1.io.MultipartRequest.calculateContentLength(MultipartRequest.java:295)
    at com.codename1.io.MultipartRequest.initConnection(MultipartRequest.java:128)
    at com.codename1.io.ConnectionRequest.performOperationComplete(ConnectionRequest.java:798)
    at com.codename1.io.NetworkManager$NetworkThread.run(NetworkManager.java:340)
    at com.codename1.impl.CodenameOneThread.run(CodenameOneThread.java:176)

user.jpg is present in the path supplied. Is this a new bug?

[EDIT]

I think the path to the file keeps returning null, even though the file is presentin FileSystemStorage. This is the exception when I try to create the image to be uploaded from an InputStream

[EDT] 0:0:0,1 - Exception: java.lang.NullPointerException - null
    at com.codename1.io.Storage.createInputStream(Storage.java:172)
    at com.jajitech.agenci.webservice.SignUpService.saveWorker(SignUpService.java:49)
    at com.jajitech.agenci.login.signup.SignUp.completeSignUp(SignUp.java:333)
    at com.jajitech.agenci.login.signup.SignUp.lambda$completeSignUpForm$3(SignUp.java:304)
    at com.codename1.ui.util.EventDispatcher.fireActionSync(EventDispatcher.java:459)
    at com.codename1.ui.util.EventDispatcher.fireActionEvent(EventDispatcher.java:362)
    at com.codename1.ui.Button.fireActionEvent(Button.java:687)
    at com.codename1.ui.Button.released(Button.java:728)
    at com.codename1.ui.Button.pointerReleased(Button.java:835)
    at com.codename1.ui.LeadUtil.pointerReleased(LeadUtil.java:153)
    at com.codename1.ui.Form.pointerReleased(Form.java:3694)
    at com.codename1.ui.Component.pointerReleased(Component.java:4691)
    at com.codename1.ui.Display.handleEvent(Display.java:2352)
    at com.codename1.ui.Display.edtLoopImpl(Display.java:1244)
    at com.codename1.ui.Display.mainEDTLoop(Display.java:1162)
    at com.codename1.ui.RunnableWrapper.run(RunnableWrapper.java:120)
    at com.codename1.impl.CodenameOneThread.run(CodenameOneThread.java:176)

Please what could be wrong that my calls to an existing file in the FIleSystemStorage returns null

[EDIT 2]

Here is my complete method, using InputStream. I had tried using normal path with same error. The line on createInputStream returns null.

try {
            MultipartRequest request = new MultipartRequest();
            request.setPost(true);
            request.setUrl(URL+"/agenci/worker/addWorker/");
            request.addArgument("name", getName());
            request.addArgument("dob", getDob());
            request.addArgument("address", getAddress());
            request.addArgument("email", getEmail());
            request.addArgument("phone", getPhone());
            request.addArgument("agencyId", getPass());
            request.addArgument("gender", getGender());
            try
            {
                InputStream is = Storage.getInstance().createInputStream(dir  + "a.jpg");
                Image img = Image.createImage(is);
                EncodedImage em = EncodedImage.createFromImage(img, true);
                byte[] data = em.getImageData();
                is.close();
                request.addData("photoFile", data , "image/jpeg");
            }catch(Exception er){System.out.println("error3");er.printStackTrace();}
            NetworkManager.getInstance().addToQueueAndWait(request);
            if(request.getResponseData() == null)
            {
                return "error1";
            }

The Exception

Exception: java.lang.NullPointerException - null
    at com.codename1.io.Storage.createInputStream(Storage.java:172)