Trouble Shooting_Download Program Error

Follow the several simple steps to know how to upload the sketch, you will also learned some useful tips to avoid burn your board.

Here I will use DFRobot Uno and Romeo as example On Win10. And the Arduino IDE is the 1.6.5.
 

All the first thing to do is plug your USB cable with the board. The power LED is on. 
If you are gonna use servo/motor/step etc, please donot use them on Arduino board without a GOOD external power supply attached! Or the low power will cause bootloader lost. Btw, it can be fixed.

1 Check your Arduino Board Serial Port in your Device manager.
 

If your Arduino IDE is not installed by ***.exe but by unzipping a ***.zip file. Then you may have to install the driver manually to see the right board serial port.

2 Open sketch"blink" or write your code in Arduino IDE

3 Choose Board as showing in the Device manager or check the specification on its product page . Here, they are 

Leonardo COM3
Uno COM7

4 Upload your sketch, it will compile automatically before uploading.

5 It will be done in a seconds.
 

Or failed:

Fail Reason:

1 Board / Port not right.

2 Bootloader lost

3 Sketch not right( Compiling failed but not board problem )

4 Serial port was occupied. 
e.g.
4.1 BLE was Linked ( BLE shares the same serial port with usb port )
4.2 Wires plugged in I/O Pin 0,1, i.e. RX/TX
 

5 Forbidden operations were taken when uploading, unplug the USB cable and repower again.

6 Some virus anti software might cause uploading process very slowly.