Hi. I am not sure I understand the issue correctly but I will try to help. I have two NucBox G3 and I never had issues with them, however I did had to understand something about USB ports. What is the maximum power in watts the g3 can provide to each USB 3 is 5W (source: their support after I emailed them). I was noticing that a nvme I had attached via usb to my g3/truenas was faiing constantly (https://sh.itjust.works/post/20409332) and in the end I realised this was due to power draw. I moved the “heavy consumption” nvme to the internal port and used the “low consumption” outside and I had no issue at all. I would also like to say that I had similar issues also on the PI4Bs (due to power consumption) and they too were hell to debug. I hope it helps and good luck.

This is the way

I could format it and try but the moment I do I lose the ability to debug the issue and learning from the problem. So I may temporary solve it but it may happen again. I wonder if someone knows what I can check/test/run to identify what broke.

Thanks for the quick reply 👍

The next step I would try would be to boot an other install, like a liveusb or a raspbian, on the same usb port, to completely eliminate a hardware problem if it boots properly.

Good advice. I moved the usb drive from another (working) PI and attached it to the same USB port. It boots correctly. It is not the USB port nor power.

If it is a software problem, it seems to happen very early in the boot process, so my bet would be a corrupted initramfs/initrd (or what is equivalent on a Pi). No idea how you could debug and fix that on Ubuntu, though (especially on a Pi where /boot is… different).

I believe it is something like that. Or it is not mounting the drive correctly and not finding it, or it is something else. I just wish there was a better (or any) error printed on the console. I tried to attach a keyboard to get to a shell with no success. I honestly could just reformat the drive and use a clean install, but it is the last resource. I would like to understand what happened so I can learn from it and avoid it in the future (or learn a path to fix it).