I'm getting error like this while uploading the program. What to do???
Arduino: 1.6.8 (Windows 7), Board: "Arduino/Genuino Uno"
C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avr-ar: unable to rename 'core\core.a'; reason: File exists
exit status 1
Error compiling for board Arduino/Genuino Uno.
Sketch uses 1,066 bytes (3%) of program storage space. Maximum is 32,256 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 2,039 bytes for local variables. Maximum is 2,048 bytes.
avrdude: ser_open(): can't open device "\.\COM1": The system cannot find the file specified.
Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.