I just got the Uno in the mail and got that error out of the box on COM3. I changed it to COM4 and it works to upload. I changed it back to COM3, same error. Back to COM4 and it works again. Good luck!
I just got the Uno in the mail and got that error out of the box on COM3. I changed it to COM4 and it works to upload. I changed it back to COM3, same error. Back to COM4 and it works again. Good luck!