code: protected IOException readError(final HttpURLConnection connection) throws IOException {
  		int status = connection.getResponseCode();
  		InputStream input = connection.getErrorStream();
  
  		try {
  			String message = input == null ? "No error description" : readString(connection, input);
  			if (message.length() > MAX_RPC_EXCEPTION_MESSAGE_LEN) {
  				message = message.substring(0, MAX_RPC_EXCEPTION_MESSAGE_LEN) + "...";
  			}
  			message = message.replace("\n", " ");
  			message = message.replace("\r", " ");
  
  			throw new RpcException(status, message);
  		} finally {
  			closeLogExc(input);
  		}
  	}
docs: Reads an unexpected exception, throws RpcException.