Unable to upload program in arduino UNO atmega 328P

Development Tools IDE 1.x
1

Arduino: 1.8.10 (Windows 10), Board: "Arduino Nano, ATmega328P (Old Bootloader)"

Sketch uses 1918 bytes (6%) of program storage space. Maximum is 30720 bytes.
Global variables use 184 bytes (8%) of dynamic memory, leaving 1864 bytes for local variables. Maximum is 2048 bytes.
C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avrdude -CC:\Program Files (x86)\Arduino\hardware\tools\avr/etc/avrdude.conf -v -patmega328p -carduino -PCOM8 -b57600 -D -Uflash:w:C:\Users\abrde\AppData\Local\Temp\arduino_build_566972/Blink.ino.hex:i

avrdude: Version 6.3-20190619
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch

System wide configuration file is "C:\Program Files (x86)\Arduino\hardware\tools\avr/etc/avrdude.conf"

Using Port : COM8
Using Programmer : arduino
Overriding Baud Rate : 57600
avrdude: ser_open(): can't open device "\.\COM8": The system cannot find the file specified.

avrdude done. Thank you.

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.

2

Select the correct port from the tools -> port menu.

The correct port will be the one that is not shown when the tools menu is opened with the arduino not plugged in, and is shown when it is plugged in. Depending on whether it is an official or clone (they use different serial adapter IC's), the port number may follow the board around to different usb ports, or it may get a different number from each usb port.

If the menu is greyed out with the board connected, try swapping to a known good USB cable, there has been a plague of DOA and failure prone cables in electronics hobby circles (i think some of the cables that are getting shipped by some vendors with arduino kits may be the bad ones). Also, try a different USB port, particularly if you are currently using a USB 3.0/3.1 port - usb 3 has fallen somewhat short of the promise of backwards compatibility. If your computer only has USB 3 ports, you can put a usb 2.0 hub between the usb 3 port and arduino, which deals with USB 3 crap - note that this only effects the usb3 ports on some computers; the ones on mine work fine.

If the board used to work, on the same computer, but now does not detect, that is a very bad sign indeed.

If the menu is greyed out, but you never used this board on that computer - could it be a clone?

Clones are very common and cheap - and one of the ways they do this is with much cheaper serial adapter IC, almost universally a ch340g, but this requires different drivers - the nano has two larger IC's, a square one (that's the mega328p) and a second one, usually on the bottom - that's the serial adapter. Check the markings on that chip If it is a CH340g, google ch340g, the name of your OS, and the word drivers, and download the drivers (it's a program called ch341ser.exe, as i recall, with ghastly engrish, but it works fine). If it's a FTDI FT232, the drivers that come with the IDE (and are installed by the installer) ought to work. If you used the .zip package, though, you will need to manually install these drivers; they're located in the drivers folder of the arduino folder you unzipped in that case.