Retrofit. java.net.ProtocolException: expected * bytes but received *

Question

I'm trying to do a Multipart POST request through Retrofit2, where I upload to the API a custom file.

It randomly fails with this Exception:

W/System.err: java.net.ProtocolException: expected 154 bytes but received 634

Does anyone could put some light on it?

This is my code in the interface:

@Multipart
@POST("recordings/{id}/{rec_id}/")
Call<ResponseBody> uploadRecording(@Path("id") String id, @Path("rec_id") String rec_id, @Part MultipartBody.Part bleFile);

In the constructor:

public ApiConnectionManager(Context con){
    Gson gson = new GsonBuilder()
            .setDateFormat("yyyy-MM-dd'T'HH:mm:ssZ")
            .create();

    OkHttpClient.Builder client = new OkHttpClient.Builder();
    HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor();
    loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
    client.addInterceptor(loggingInterceptor);

    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(con.getResources().getString(R.string.api_url)) // API url is hidden
            .addConverterFactory(GsonConverterFactory.create(gson))
            .client(client.build())
            .build();

    this.companyAPI = retrofit.create(CompanyAPI.class);
}

and in the upload method:

private void uploadFile(String id, final File bleFile) {
    MediaType MEDIA_TYPE = MediaType.parse("multipart/mixed");
    RequestBody requestBody = RequestBody.create(MEDIA_TYPE,bleFile);
    MultipartBody.Part partFile = MultipartBody.Part.createFormData("file", bleFile.getName(), requestBody);
    String recordingId = bleFile.getName().replace(".BLE","");
    Call<ResponseBody> call = companyAPI.uploadRecording(id, recordingId, partFile);
    call.enqueue(new Callback<ResponseBody>() {
        @Override
        public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) {
            Log.d(TAG+"-Upload "+bleFile.getName(),response.message());
        }

        @Override
        public void onFailure(Call<ResponseBody> call, Throwable t) {
            Log.d(TAG,"FAILED");
            t.printStackTrace();
        }
    });
}

Answer 1

After studying for a while the problem I've realized that the content of the file was always changing (as it is the output of a sensor).

It means that the file that is checked for the HEAD and the file for the BODY may not contain the same data (therefore different length), which caused the mismatch.

I solved this creating a copy of the file and sending it (the copy) instead of the original file.