This is the first time when I have installed Arduino IDE (arduino-1.8.10-windows.exe) in my Win. XP SP-3 OS and it seems that the Arduino IDE software installation is successful without any hitch.

After restarting the PC, connected it with Arduino Uno board through USB-Printer cable provided with the board and then selected Arduino Uno, Selected Port: COM3 (Arduino/Genuino Uno) - as I have verified in the Device Manager that the Arduino Uno installed in COM3 port.

As soon as I have connected Arduino Uno board to my PC, the yellow LED started blinking slowly. As I have tried uploading the sketch - File>Examples> 01.Basics>Blink - there is an Error message that says, "Error compiling for board Arduino Uno" - even though the yellow LED still kept blinking without a reasonable act from my side.

So, where have I gone wrong - either in performance or in understanding? And is there any suggestion for making things right?

I thank you.

// the setup function runs once when you press reset or power the board 
void setup(){

  // initialize digital pin LED_BUILTIN as an output. 


// the loop function runs over and over again forever 
void loop(){

  // turn the LED on (HIGH is the voltage level) 
  digitalWrite(LED_BUILTIN, HIGH);

  // wait for a second

  // turn the LED off by making the voltage LOW
  digitalWrite(LED_BUILTIN, LOW);

  // wait for a second 

  • Please edit your question to add the sketch or any new information, rather than putting it in comments. Even the "Auto format" feature in the IDE couldn't fix the code mis-alignment. I've formatted your sketch and added it to the question. Using comments before the line of code and proper line spacing make the code easier to read and find problems.
    – VE7JRO
    Dec 4, 2019 at 17:02

1 Answer 1


The yellow LED may be flashing because there may be a "Blink" LED program pre-installed on the Arduino.

To diagnose the "Error compiling for board Arduino Uno", we need to see the sketch you are trying to upload, and detailed error messages. If you go to Arduino > Preferences, check the "compilation" and "upload" checkboxes beside Show verbose output during:. Display line numbers is another checkbox you could enable.


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