Как узнать, почему изображение не загружается при использовании Volley?

Для загрузки изображения используйте класс Volleymultipart.

     package com.conceptioni.ashebbicom.util;

    import com.android.volley.AuthFailureError;
    import com.android.volley.NetworkResponse;
    import com.android.volley.ParseError;
    import com.android.volley.Request;
    import com.android.volley.Response;
    import com.android.volley.VolleyError;
    import com.android.volley.toolbox.HttpHeaderParser;

    import java.io.ByteArrayInputStream;
    import java.io.ByteArrayOutputStream;
    import java.io.DataOutputStream;
    import java.io.IOException;
    import java.io.UnsupportedEncodingException;
    import java.util.Map;

 public class VolleyMultipartRequest extends Request<NetworkResponse> {

 private final String twoHyphens = "--";
 private final String lineEnd = "\r\n";
 private final String boundary = "apiclient-" + System.currentTimeMillis();

 private Response.Listener<NetworkResponse> mListener;
 private Response.ErrorListener mErrorListener;
 private Map<String, String> mHeaders;


 public VolleyMultipartRequest(int method, String url,
                              Response.Listener<NetworkResponse> listener,
                              Response.ErrorListener errorListener) {
    super(method, url, errorListener);
    this.mListener = listener;
    this.mErrorListener = errorListener;
 }

@Override
public Map<String, String> getHeaders() throws AuthFailureError {
    return (mHeaders != null) ? mHeaders : super.getHeaders();
}

@Override
public String getBodyContentType() {
    return "multipart/form-data;boundary=" + boundary;
}

@Override
public byte[] getBody() throws AuthFailureError {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    DataOutputStream dos = new DataOutputStream(bos);

    try {
        // populate text payload
        Map<String, String> params = getParams();
        if (params != null && params.size() > 0) {
            textParse(dos, params, getParamsEncoding());
        }

        // populate data byte payload
        Map<String, DataPart> data = getByteData();
        if (data != null && data.size() > 0) {
            dataParse(dos, data);
        }

        // close multipart form data after text and file data
        dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

        return bos.toByteArray();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}


protected Map<String, DataPart> getByteData() {
    return null;
}

 @Override
 protected Response<NetworkResponse> parseNetworkResponse(NetworkResponse response)  {
    try {
        return Response.success(
                response,
                HttpHeaderParser.parseCacheHeaders(response));
    } catch (Exception e) {
        return Response.error(new ParseError(e));
    }
}

@Override
protected void deliverResponse(NetworkResponse response) {
    mListener.onResponse(response);
}

@Override
public void deliverError(VolleyError error) {
    mErrorListener.onErrorResponse(error);
}


  private void textParse(DataOutputStream dataOutputStream, Map<String, String> params, String encoding) throws IOException {
    try {
        for (Map.Entry<String, String> entry : params.entrySet()) {
            buildTextPart(dataOutputStream, entry.getKey(), entry.getValue());
        }
    } catch (UnsupportedEncodingException uee) {
        throw new RuntimeException("Encoding not supported: " + encoding, uee);
    }
}


  private void dataParse(DataOutputStream dataOutputStream, Map<String, DataPart> data) throws IOException {
     for (Map.Entry<String, DataPart> entry : data.entrySet()) {
        buildDataPart(dataOutputStream, entry.getValue(), entry.getKey());
     }
 }


   private void buildTextPart(DataOutputStream dataOutputStream, String parameterName, String parameterValue) throws IOException {
    dataOutputStream.writeBytes(twoHyphens + boundary + lineEnd);
    dataOutputStream.writeBytes("Content-Disposition: form-data; name=\"" + parameterName + "\"" + lineEnd);
    dataOutputStream.writeBytes(lineEnd);
    dataOutputStream.writeBytes(parameterValue + lineEnd);
}


  private void buildDataPart(DataOutputStream dataOutputStream, DataPart dataFile, String inputName) throws IOException {
    dataOutputStream.writeBytes(twoHyphens + boundary + lineEnd);
    dataOutputStream.writeBytes("Content-Disposition: form-data; name=\"" +
            inputName + "\"; filename=\"" + dataFile.getFileName() + "\"" + lineEnd);
    if (dataFile.getType() != null && !dataFile.getType().trim().isEmpty()) {
        dataOutputStream.writeBytes("Content-Type: " + dataFile.getType() + lineEnd);
    }
    dataOutputStream.writeBytes(lineEnd);

    ByteArrayInputStream fileInputStream = new   ByteArrayInputStream(dataFile.getContent());
    int bytesAvailable = fileInputStream.available();

    int maxBufferSize = 1024 * 1024;
    int bufferSize = Math.min(bytesAvailable, maxBufferSize);
    byte[] buffer = new byte[bufferSize];

    int bytesRead = fileInputStream.read(buffer, 0, bufferSize);

    while (bytesRead > 0) {
        dataOutputStream.write(buffer, 0, bufferSize);
        bytesAvailable = fileInputStream.available();
        bufferSize = Math.min(bytesAvailable, maxBufferSize);
        bytesRead = fileInputStream.read(buffer, 0, bufferSize);
    }

    dataOutputStream.writeBytes(lineEnd);
}

   public class DataPart {
    private String fileName;
    private byte[] content;
    private String type;

    public DataPart() {
    }

    public DataPart(String name, byte[] data) {
        fileName = name;
        content = data;
    }

    String getFileName() {
        return fileName;
    }

    byte[] getContent() {
        return content;
    }

    String getType() {
        return type;
    }

 }
 }

//////////////////// Используйте этот класс, как показано ниже//////////////////////////

   VolleyMultipartRequest volleyMultipartRequest = new   VolleyMultipartRequest(Request.Method.POST, Constants.edit_photo,
            new Response.Listener<NetworkResponse>() {
                @SuppressLint("ApplySharedPref")
                @Override
                public void onResponse(NetworkResponse response) {
                    try {
                         //Response

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }

                    pb.setVisibility(View.GONE);
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                }
            }) {


        @Override
        protected Map<String, String> getParams() {
            Map<String, String> params = new HashMap<>();
            params.put("API", "edit_photo");
           //all params here
            return params;
        }


        @Override
        protected Map<String, DataPart> getByteData() {
            Map<String, DataPart> params = new HashMap<>();
            long imagename = System.currentTimeMillis();
            params.put("var_image", new DataPart(imagename + ".png", getFileDataFromDrawable(bitmap)));
            return params;
        }
    };

    //adding the request to volley
            Volley.newRequestQueue(ActivityProfileDetailSlider.this).add(volleyMultipartRequest);

///////////////////////////////////////////////////////////////

 public byte[] getFileDataFromDrawable(Bitmap bitmap) {
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.PNG, 80, byteArrayOutputStream);
    return byteArrayOutputStream.toByteArray();
  }

В вашей функции onCompleted() вам нужно проверить, есть ли исключение. Exception даст вам подробную информацию о том, почему он не работает.

public void onCompleted(Exception e, JsonObject result) {
                hideProgressDialog();

                if(e != null){
                  //IN ERROR CASE
                   Log.d(TAG, e.getLocalizedMessage());
                  }else{

                Log.d(TAG,"photo uploaded");
                Toast.makeText(ProfileActivity.this, "Photo uploaded", 
                Toast.LENGTH_SHORT).show();
                //do stuff with result
                 }
              }
            });

Опубликуйте текст исключения в своем сообщении, если вы не понимаете ошибку, которая печатается в LogCat.