I am trying to upload sketches to my Arduino Uno from my 64 bit Windows 7 PC, but any sketch I try gets stuck on the "uploading" phase.
I have tried uploaded a blank sketch but nothing completes. Here is my error message:
Arduino: 1.8.5 (Windows 7), Board: "Arduino/Genuino Uno"
Sketch uses 444 bytes (1%) of program storage space. Maximum is 32256 bytes. Global variables use 9 bytes (0%) of dynamic memory, leaving 2039 bytes for local variables. Maximum is 2048 bytes. avrdude: ser_open(): can't open device "\.\COM3": Access is denied.
An error occurred while uploading the sketch
This report would have more information with "Show verbose output during compilation" option enabled in File -> Preferences.