Can't find COM port for Arduino UNO

I Can not find COM port for Arduino UNO
It was Arduino UNO is working properly and when I finished them I added Arduino Nano place taking into account the change Board and when I finished I wanted to refer to the Arduino UNO and when I wanted to Upload code did not I can promise has COM6 disappeared attributed Arduino Nano appeared but Arduino UNO does not and LED ON is shines.

Windows will reserve ports (based on VID and PID of the USB device I think) and sometimes that can become confusing. Look on the internet for ways to release them. Bellow is a how to:

        1) Open Command Prompt as Administrator (you may need to research how to do this for your version of windows).

        2) (this step is not needed on Windows 10 but is on 7) Set Environment variable  “set devmgr_show_nonpresent_devices=1”. 
            At the command prompt, type the following command and then press ENTER: 

            set devmgr_show_nonpresent_devices=1

        3) Run Device Manager with Environment variable. Type the following at command prompt, and then press ENTER:

            start devmgmt.msc

        4) Show hidden devices. Point to View and left click, then point to 
            Show hidden devices and left click. This will display reserved ports.

        5) View hidden COM ports. Go to Ports (COM & LPT) and expand that 
            section.

        6) Remove COM1. Remove COM1 device in the list of ports, and optionally others 
            that are grayed out but have a specific COM port number assigned. Right click 
            on the grayed out device, choose Uninstall, and then OK in the dialog box that 
            appears.

        7) Close Device Manager.

        8 ) Exit command prompt.

ron_sutherland:
Windows will reserve ports (based on VID and PID of the USB device I think) and sometimes that can become confusing. Look on the internet for ways to release them. Bellow is a how to:

        1) Open Command Prompt as Administrator (you may need to research how to do this for your version of windows).

2) (this step is not needed on Windows 10 but is on 7) Set Environment variable  “set devmgr_show_nonpresent_devices=1”.
            At the command prompt, type the following command and then press ENTER:

set devmgr_show_nonpresent_devices=1

3) Run Device Manager with Environment variable. Type the following at command prompt, and then press ENTER:

start devmgmt.msc

4) Show hidden devices. Point to View and left click, then point to
            Show hidden devices and left click. This will display reserved ports.

5) View hidden COM ports. Go to Ports (COM & LPT) and expand that
            section.

6) Remove COM1. Remove COM1 device in the list of ports, and optionally others
            that are grayed out but have a specific COM port number assigned. Right click
            on the grayed out device, choose Uninstall, and then OK in the dialog box that
            appears.

7) Close Device Manager.

8 ) Exit command prompt.

This should be a sticky !

ron_sutherland:
Windows will reserve ports (based on VID and PID of the USB device I think) and sometimes that can become confusing. Look on the internet for ways to release them. Bellow is a how to:

        1) Open Command Prompt as Administrator (you may need to research how to do this for your version of windows).

2) (this step is not needed on Windows 10 but is on 7) Set Environment variable  “set devmgr_show_nonpresent_devices=1”.
            At the command prompt, type the following command and then press ENTER:

set devmgr_show_nonpresent_devices=1

3) Run Device Manager with Environment variable. Type the following at command prompt, and then press ENTER:

start devmgmt.msc

4) Show hidden devices. Point to View and left click, then point to
            Show hidden devices and left click. This will display reserved ports.

5) View hidden COM ports. Go to Ports (COM & LPT) and expand that
            section.

6) Remove COM1. Remove COM1 device in the list of ports, and optionally others
            that are grayed out but have a specific COM port number assigned. Right click
            on the grayed out device, choose Uninstall, and then OK in the dialog box that
            appears.

7) Close Device Manager.

8 ) Exit command prompt.

Thanks you but it did not work.

1 Like

I followed the advice but went further.

  1. Disconnect as many USB devices as possible.
  2. Do as Ron said but here is where I went OTT I deleted every COM port.
  3. Ran "wise" registry cleaner
  4. Ran CCLEANER too
  5. Re-boot computer and start adding in the USB devices you disconnected one by one (slowly) until they are all back up and running
  6. Connect one Arduino and if it shows up and installs its needed drivers then fine I tried the BLINK sketch
  7. If it did not work correctly then I went and got the 340/341 drivers and installed them and did another re-boot then step 5. again.

Only issue I have had since was with an older WI-FI adaptor which is the one I am playing with to connect to ESP8266 devies right now. Its hit and miss at being recognised at the best of times. Otherwise it helped out a great deal. There is for sure something with IDE 1.6.6 that messes up USB and the Arduinos.

Unplug the USB and plug it to different socket.

That worked for me.

I was having problems where it kept trying to use COM 10, which did not work. (Windows 7)
In Device Manager, I opened Properties on Arduino Uno (COM3) under Ports (COM & LPT)
Then Port Settings, Advanced, and Click COM Port Number button. It showed a list of port numbers, but all the ones below COM10 were marked In Use. I could force it to pick a lower number after answering Yes on a couple warnings, but the next time I used a different board, it wanted to use 10 again.

Solution:

  1. Device Manager main page: Right click the port and select DISABLE
  2. Go into the advanced properties port selection, and select each of the in-use ports and accept the warnings. This clears the in use flag.
  3. Select the port number you want to use in Properties, close it, then enable the port again in Device Manager.

Now all the port numbers will be free to use until they get tied up again for whatever reason.

This fixed it for me, I had searched many forums without luck until this. arduino uno - avrdude ser_open() can't set com-state - Arduino Stack Exchange

I have been facing similar issue.my arduino uno is not detected by windows 8 as well as ubuntu machines.arduino ide seems to be stuck to com3 port but in device manager nothing changed , neither is com3 visible in device manager nor arduino ide is able to connect com3.
So I used usbasp program mer to upload hex on Arduino Uno .that worked.but when I connect ardino uno board directly it fails.
Definitely something has messed with com3 port and Arduino ide.kind of stuck in for long time.kindly suggest some solution.
Regards
Udu

@udaym

If you are referring to the right bottom corner in the IDE still showing COM3, that is because the IDE will remember (and use) the last selected port.

Have you tried to burn the bootloader using usbasp?

Using usbasp I was able to upload the hex file consisting sketch_with_ bootloader.hex and that worked ok but still my Arduino Uno is not detected.

...,...........---------------------------------------
12/9/2020
Today I tried with uploading .../../optiboot/bootloader328.hex also with usbasp .no issues while uploading.But my Arduino UNO is still not detected.

So I am approaching a conclusion that my onboard atmega16u is having issues.So tried shirting pin 5 and 6 on icsp1 while board is ON.but no luck.
Tried to upload atmega16u_bootloader.hex with uspasp..
but got error "chip not enabled" on progisp.

Someone please suggest any work around so that atmega16u is reset properly..as the board is working fine with uspasp a I don't want to buy a new one unnecessarily.

Regards
Uday.

Today tried to detect atmega16u using dfu-programmer on xUbuntu but unsuccessful.

Actually it used to work earlier especially when I had interfaced Arduino Uno with enc28j60 module for LAN connection success fully.
Used it after a long gap and suddenly found it undetectable.

But probably I can still use Arduino Uno for LAN ,wifi connection as I was able to use usbasp atmega8 programmer for uploading hex file.

So keeping this on hold until I encounter a proper fix for atmega16u.

Regards
(REMOVED)