I cannot compiler just only normal code "Blink" in example. After I add ESP8266 module in IDE. I found error.
C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-ar: unable to rename 'core\core.a'; reason: Permission denied
I try to uninstall Arduino IDE and new install but problem is still happen. I permit all full control in the folder. I use Windows10. Before this it worked well.