COM port is busy (access denied) or generally just doesn't work

[mortenmoulder]

I'm running Windows 11 and I have been experiencing some weird issues with my PPK2. Once in a while it works flawlessly, as in no issues what so ever. Then suddenly after opening the Power Profiler app, it simply will not connect to the device. I can see it in the list, but it never connects.

I read multiple places that I should try to downgrade to 3.7.1. That did not solve it either.

I also read people saying, that if I open the Programmer first, put it into bootloader mode, and then open Power Profiler, I should accept the firmware install. That has surprisingly worked a few times.

If I open Programmer, put it into bootloader mode, open Power Profiler and proceed with the firmware install, I get an "Error while setting up device XXXXXX: Opening COM4: Access denied". I tried as administrator, but to no avail.

If I use Microsoft's Process Explorer, and I search for usbser using this guide, I get 0 results back, which probably means the COM port isn't being used by another application.

If I unplug it, plug it back in, it's now COM3 because it's out of the bootloader again. If I open Power Profiler and select the device, I just get this in the log and nothing else:

2022-01-14T00:16:51.887Z INFO Application data folder: C:\Users\morte\AppData\Roaming\nrfconnect\pc-nrfconnect-ppk
2022-01-14T00:16:51.953Z DEBUG App pc-nrfconnect-ppk v3.1.3 official
2022-01-14T00:16:51.953Z DEBUG App path: C:\Users\morte\.nrfconnect-apps\external\3.7 compatible apps\node_modules\pc-nrfconnect-ppk
2022-01-14T00:16:51.953Z DEBUG nRFConnect 3.7.1 is not supported by the app (^3.6.1)
2022-01-14T00:16:51.953Z DEBUG nRFConnect path: C:\Users\morte\AppData\Local\Programs\nrfconnect\resources\app.asar
2022-01-14T00:16:51.953Z DEBUG HomeDir: C:\Users\morte
2022-01-14T00:16:51.954Z DEBUG TmpDir: C:\Users\morte\AppData\Local\Temp
2022-01-14T00:16:53.608Z INFO Validating firmware for device with s/n XXXXXX
2022-01-14T00:16:53.619Z INFO Opening device with s/n XXXXXX

Completely dead. If I reboot my PC, it's most likely going to work again, but that's a huge pain in the rear to do every time.

Is this a Windows problem?

EDIT: Just rebooted and now it works again. So weird.

EDIT 2: Hmmmmmmmmmm after running Power Profiler for a few minutes, I wanted to open Debian running in WSL (which wasn't running at the time). Right after opening it, Power Profiler disconnected from the PPK2 and now I'm back to the original errors. Seems like WSL is messing something up. At least now I know how to replicate it!

[nicolai-nordic]

Hello @mortenmoulder. Sorry it took so long to get back to you. I haven't seen this behavior before, so I'm not really sure what the best way to proceed with this is.

We are in the process of releasing nRF Connect for Desktop 3.10, which will include the option of turning on verbose logging for nrf-device-lib, i.e. the underlying library handling device operations. Enabling verbose logging while the device is in this unselectable state might give us some useful information.

As I write this we are doing the final testing stages on 3.10, so hopefully it will be available within a few days.

[mortenmoulder]

Hi @nicolai-nordic - thanks for the update. I'll give it a go when it's released.

In the meantime, you might want to try to install WSL (Debian for example) on a Windows PC. I've been consistently experiencing these issues, and it's only when I launch Debian through WSL that the device doesn't work anymore. You can install Debian through the Microsoft Store.

[nicolai-nordic]

I had WSL with Ubuntu installed and tried launching that, but it didn't happen. I'm not on Windows 11 yet though, so I will look into this.

[mortenmoulder]

Aha, hmmm. That might be a Windows 11 issue then!

[mortenmoulder]

Just checking in to say, that this issue is still happening and it's VERY annoying. Have to reboot my PC every time I want to use my PPK2.

[wlgrd]

To me it sounds like Windows is reporting the PPK2 as available up to the software. We have never seen this on any Linux distribution, Mac OSX or Windows 10. Are you able to test this on another computer, not using Windows 11?

[mortenmoulder]

@wlgrd I don't think that's the right approach, to be fair. Let's say I cannot replicate on Windows 10, then nothing happens.

I'm sure there are people working at Nordic Semiconductor who has a PPK2 and who runs Windows 11. Installing WSL through Microsoft Store takes ~3 minutes.

[wlgrd]

This is to ensure that the software and your PPK2 are working as it should and that W11 is indeed the culprit. I know how flaky the use of serial ports can be with Windows, and adding WSL into the mix makes it even worse and will not only affect the PPK2 for sure. Can you confirm that this is only happening when WSL is running at the same time?

[mortenmoulder]

@wlgrd I can confirm that if I have PPK2 connected and I'm monitoring, if I open WSL it immediately disconnects and is unable to connect to PPK2 until I reboot.

I'm not even doing anything with WSL. I just open the Debian terminal and that's it.

I will test on a Windows 10 machine later, but thus far I have not been able to replicate it on Windows 10. Luckily I have 2x Windows 11 and 1x Windows 10 machine at home, so I should be able to confirm it's a Windows 11 issue.

[mortenmoulder]

@wlgrd Can confirm that it is not happening in Windows 10, but it's happening on two Windows 11 machines with Debian installed in WSL.

I have not tried a fresh install and just installed the Power Profiler and Debian in WSL, but I think it's safe to assume, that the issue is happening in Windows 11.

However, all of my other serial ports work. I even tried flashing a pretty large firmware to an Arduino, then opened WSL, and it didn't stop flashing.

Anyone I can reach out to from Nordic Semiconductor, who can work on this issue? Having Windows 11 and running Linux commands via WSL is not an uncommon thing as a developer.

[wlgrd]

Happy to hear that it is working as intended under Windows 10.
I have reported this internally and will follow up when I have more answers. As stated in the user guide, only Windows 8 and 10 are supported but as more users move to Windows 11 we need to figure out what causes this and hopefully be able to fix it.

[mortenmoulder]

@wlgrd Our entire enterprise of 1000+ people are using Windows 11. It came out half a year ago, so I think Windows 11 support is a requirement (with WSL, which is also common for the likes of us). Thank you.

[jonasem]

I tried this now on Windows 11, Ubuntu WSL2, PPK v3.4.3, nRF for Desktop v3.11.0 and could not reproduce. I even flashed the ppk with some other fw and flashed it again with the bundled fw from the ppk app and it just works.

Is there anything else that is done with your WSL except from installing ubuntu from the store? Trying to reproduce as much as possible.

I haven't used the launcher version reported 3.7.1, but the most current one, 3.11.0, maybe there is something in between there that fixes it? Have you tried recently with a current version of nRT Connect for Desktop?

[jonasem]

I downgraded to nRF Connect 3.7.1 and ppk v3.1.3, and it still works fine, launching both Ubuntu and Debian mid-trace.

[mortenmoulder]

@jonasem Thank you for trying!

Try launching WSL via Windows Terminal (it's also in the Microsoft Store). I can replicate without, but worth a shot.

Hmm. I honestly don't know how much I've changed. I know there's something called usbipd in WSL, that allows devices to pass through, but you actively have to select those devices. It's used for flashing other chips in my case. See if you can at least install that and still not replicate it. Remember to terminate the running "OS" with wsl -t {distro name} (that you can find with wsl -l -v)

You are using WSL 2? wsl --set-default-version 2