Android Volley: BasicNetwork.performRequest: Unexpected response code 400

Question

E/Volley: [1888] BasicNetwork.performRequest: Unexpected response code 400 for https://pastebin.com/raw/2WMVsLei

Problem only Pastbin. I will try another https api but can't face any issue. Issue only occurs with pastebin api.

public void logIn() {

    String URL="";
    try {

        JSONObject old = new JSONObject(Constantse.decrypt(PreferenceUtils.getAllData(con)));
        String updateUrl = old.getString("DefUpdateURL");
        URL = updateUrl;

    }catch (Exception e){
        System.out.println(e);

    }

    StringRequest stringRequest = new StringRequest(Request.Method.POST, URL, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {

            try {
                JSONObject old = new JSONObject(Constantse.decrypt(PreferenceUtils.getAllData(con)));
                JSONObject news = new JSONObject(Constantse.decrypt(response));

                System.out.println(Constantse.decrypt(response));

                if(Integer.parseInt(news.getString("UpdateVersion")) > Integer.parseInt(old.getString("UpdateVersion"))){
                    PreferenceUtils.setCredientials(con,news.getJSONArray("Servers").toString());
                    PreferenceUtils.setPayload(con,news.getJSONArray("payload").toString());
                    PreferenceUtils.setAllData(con,response);
                    editor.putInt("current_server", 0).apply();
                    editor.putInt("current_payload", 0).apply();
                    Toast.makeText(getActivity(),"Update Success",Toast.LENGTH_SHORT).show();
                    getActivity().finish();
                    startActivity(getActivity().getIntent());
                }else{
                    System.out.println("Don't Update");
                    Toast.makeText(getActivity(),"Already Updated",Toast.LENGTH_SHORT).show();
                }

            }catch (Exception e){
                System.out.println(e);
            }

        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            logIn2(); // this is additional api for server & payload
            Toast.makeText(getActivity(),"Use Next Server",Toast.LENGTH_SHORT).show();
            System.out.println(error);
        }


    }) {
        @Override
        protected Map<String, String> getParams() {
            Map<String, String> params = new HashMap<String, String>();
            return params;

        }
    };
    stringRequest.setShouldCache(false);// for cash clear
    Volley.newRequestQueue(con).add(stringRequest);
    Volley.newRequestQueue(con).getCache().clear();// for cash clear
}