Retrofit 2 : End of input at line 1 column 1 path $

Have made a thorough searching to this particular problem but while implementing answers under each question I encountered, am still getting the same output:

 End of input at line 1 column 1 path $ 

I perfomed my Request on PostMan and I got expected output: Here is the Screenshot of the Postman Request

Interfaces

 @POST(Constant.API_REQUEST)
    Observable<ServerResponse> postToWinnersList(@Body ServerRequest serverRequest);

ApiClient

public class ApiClient {
    public static Retrofit retrofit;

    private static OkHttpClient.Builder okHttpClientBuilder;
    private static HttpLoggingInterceptor loggingInterceptor;


    public static Retrofit getApiClient(){
        if (retrofit == null){
//            create instance of Httpclient
            okHttpClientBuilder = new OkHttpClient.Builder();
            loggingInterceptor = new HttpLoggingInterceptor();
            loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);

            if(BuildConfig.DEBUG){
                okHttpClientBuilder.addInterceptor(loggingInterceptor);
            }
//            instance of retrofit
            retrofit = new Retrofit.Builder().baseUrl(Constant.BASE_URL).
                    addCallAdapterFactory(RxJava2CallAdapterFactory.create()).
                    addConverterFactory(GsonConverterFactory.create())
                    .client(okHttpClientBuilder.build())
                    .build();
        }
        return retrofit;
    }
}

Retrofit/RxJava Request Code:

     Observable<ServerResponse> response = apiInterface.postToWinnersList(serverRequest);
                response.observeOn(AndroidSchedulers.mainThread())
                        .subscribeOn(Schedulers.io())
                        .subscribeWith(new DisposableObserver<ServerResponse>() {
                            @Override
                            public void onNext(ServerResponse serverResponse) {
                                AVLoadingIndicatorView1.setVisibility(View.GONE);
                                txtSubmitWinner.setVisibility(View.VISIBLE);
                            }

                            @Override
                            public void onError(Throwable e) {
                                AVLoadingIndicatorView1.setVisibility(View.GONE);
                                txtSubmitWinner.setVisibility(View.VISIBLE);
                                Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_LONG).show();
                            }

                            @Override
                            public void onComplete() {
                                showShortMsg(getString(R.string.submit_success));
                            }
                        });

Kindly help, thanks in Advance.

You only get that error when something is wrong with your json response, Check again to make sure both the error response and correct response are well formatted.

Enter wrong credentials using postman and see what the output looks like.