I'm trying to upload to AWS S3 by using thier AWS for Android SDK but both sample project within SDK and my project give the following error on devices while emulator runs without problem. So there's no problem with my AWS account. "Host name may not be null." Upload Code : s3Client.createBucket(Constants.getBucket()); PutObjectRequest por = new PutObjectRequest(Constants.getBucket(), record.getFile().getName(), record.getFile()); s3Client.putObject(por); Any help is appreciated.