Hi @FJDKGU ,
welcome to the Arduino Forum!
To get optimum support you should add some more information:
- What is the Arduino IDE version you use?
- Which board are you using (e.g. Arduino UNO, ESP32, Arduino MEGA, ...)?
- Post the sketch you are using in code tags
- Post the complete error message in code tags
You'll find the code tags in the editor menu:
You might also read this
How to get the best out of this forum - Development Tools / IDE 1.x - Arduino Forum
You can find some instructions regarding the error message here
https://www.instructables.com/A-solution-to-avrdude-stk500getsync-not-in-syn/
With further information about your setup it would be easier to give specific support ...
ec2021