Android Volley - BasicNetwork.performRequest: Unexpected response code 400

One way of doing this without changing Volley's source code is to check for the response data in the VolleyError and parse it your self.

As of f605da3 commit, Volley throws a ServerError exception that contains the raw network response.

So you can do something similar to this in your error listener:

/* import com.android.volley.toolbox.HttpHeaderParser; */
public void onErrorResponse(VolleyError error) {

    // As of f605da3 the following should work
    NetworkResponse response = error.networkResponse;
    if (error instanceof ServerError && response != null) {
        try {
            String res = new String(response.data,
                       HttpHeaderParser.parseCharset(response.headers, "utf-8"));
            // Now you can use any deserializer to make sense of data
            JSONObject obj = new JSONObject(res);
        } catch (UnsupportedEncodingException e1) {
            // Couldn't properly decode data to string
            e1.printStackTrace();
        } catch (JSONException e2) {
            // returned data is not JSONObject?
            e2.printStackTrace();
        }
    }
}

For future, if Volley changes, one can follow the above approach where you need to check the VolleyError for raw data that has been sent by the server and parse it.

I hope that they implement that TODO mentioned in the source file.

Me too got the same error but in my case I was calling url with blank spaces.

Then, I fixed it by parsing like below.

String url = "Your URL Link";

url = url.replaceAll(" ", "%20");

StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
                            new com.android.volley.Response.Listener<String>() {
                                @Override
                                public void onResponse(String response) {
                                ...
                                ...
                                ...

@Override
public Map<String, String> getHeaders() throws AuthFailureError {
    HashMap<String, String> headers = new HashMap<String, String>();
    headers.put("Content-Type", "application/json; charset=utf-8");
    return headers;
}

You need to add Content-Type to the header.

Try this ...

 StringRequest sr = new StringRequest(type,url, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {

            // valid response
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            // error
        }
    }){

@Override
    protected Map<String,String> getParams(){
        Map<String,String> params = new HashMap<String, String>();
            params.put("username", username);
            params.put("password", password);
            params.put("grant_type", "password");
        return params;
    }

    @Override
    public Map<String, String> getHeaders() throws AuthFailureError {
        Map<String,String> params = new HashMap<String, String>();
        // Removed this line if you dont need it or Use application/json
        // params.put("Content-Type", "application/x-www-form-urlencoded");
        return params;
    }