Downloaded ISO and created USB disk as per the documentation.
Installing on Intel® N100 × 4 with 8G memory (GMKtec NucBox G3)
Just before the 4 item menu appears, it says “/root/ not found”.
Have attempted / re-tried all steps, but nothing has worked for me. (and I’ve been at it for days)
I am not familiar with grub, unfortunately.
I’ve moved this from the Desktop Category to Support and Help as it appears you’re seeking help, rather than wanting to discuss the Ubuntu Desktop.
Looks like something went wrong when creating the USB drive. How exactly have you done that? Details matter very much here. My gut feeling tells me that you may have written the ISO to a partition instead of the whole raw block device.
Wrong:
dd if=image.iso of=/dev/sda1
And grub then can’t find the device, because the offset is wrong.
Correct:
dd ... of=/dev/sda
(don’t actually use this example and always use persitent names)
Per the documentation, I used Disk - “Restore Disk Image” (from the downloaded ISO).
I didn’t use “dd’“.
The target is a blank box with no partitions (it was scrubbed).
Thanks guiverc for moving this to the correct category.
Wait, which 4 item menu? Is it the grub menu of the live installer?
I guess you are calling it the Live installer.
1st option is Try or Install, 2nd is Use second volume… 4th takes you out to grub.
All options work to some degree; but we loop on option one, trying to install unsuccessfully.
I only mentioned grub in my OP, because I figure it may form part of the solution to my problem. Sorry if that led you astray.
If you are using the Disks application, that would mean you have a currently installed Ubuntu or Linux OS which has that application. What installed OS and release version are you using? Did you verify the download of the iso file before writing it to the USB? This is explained on the download page.
What exactly is this “blank box”?
Typically we use a simple USB flash drive (dongle) for the live/installation media. Others may or may not work. (And in any case it doesn’t need to be “scrubbed”, writing an image file (ISO or others) to a device does that).
And, indeed, as commented above, please verify the downloaded ISO before burning.
Yanec, I don’t think the target box is relevant. Per OP, it is an Intel® N100 × 4 with 8G memory (GMKtec NucBox G3).
My USB drive (dongle as you call it) is 1TB.
Version using “Disk” (just) happens to be the same version as the ISO. I don’t think that matters.
I have not checked the checksums, but given it is my third attempt with download, I kinda doubt any prob there.
Yes, that’s the grub menu of the live installer. But you said that message comes up before it. My next question would have been what happens when you just ignore it:
So something is wrong, but grub seems the wrong starting point.
I’ll say, go with the dd option and verify the USB device afterwards. You still need to verify the image before writing it, because that script calculates different hashes.
Actually, you might want to run diff-image-drive before doing anything else. No need to write it again, if it’s identical and the SHA-256 sum of the image is correct.
O Dog! I don’t seem to be very understandable, try as I might.
Let’s ignore grub for now. Yes there are 4 options. We are looping on option 1. Which is ”Try or Install”. It tries, but fails, then reboots.
So, I will use dd then. I used to know how to use it, back in the 1980s.
I won’t go down the always use persitent names path at this stage (but I appreciate the sentiment/correctness of it)
Disk reports that the USB drive is FAT32 EFI mounted at /boot/efi. device /dev/nvme0n1p1.
I guess I’ll be using that device for the dd output file.
Could someone point me at the expected checksums please.
No, you shouldn’t use external HDDs or SSDs or even a SD/microSD (not in a USB adapter) for creating live/installation media. Some work for that purpose, others just don’t. It may depend on the target computer as well, on how it initializes devices. Again, use a simple known good USB stick large enough.
Ahha! That might explain it.
Well I’ll purchase I nice big USB stick tomorrow. The ones I have here are a tad small.
BTW, I have had my suspicions about the target computer too (GMKtec NucBox G3) … many unexplained crashes running Win11. Hence I scrubbed it clean. (Windows refugee)
Is your installation attempt failing at this step? If so, is there any change the following warning applies to you?
Warning
Some PCs use Intel RST (Rapid Storage Technology), which is not supported by Ubuntu. If this is the case, you won’t be able to proceed with the installation unless you disable RST on your machine.
If you encounter this alert, see Reconfigure Windows to use AHCI to resolve the issue. To learn more, see Intel RST during Ubuntu installation.
We do not get that far. It fails before that screen. And I don’t have Windows installed anywhere this week.
Thanks for the RST link.
Sorry, I got it now. It’s the grub menu you are talking about. Good luck when you try with a new USB.
Can I share my thoughts on this matter?
When we use Disks>Drive Options>Restore Disk Image we end up with a Ubuntu Try/Live/Install operating system.
So, I do not see the point of writing the Ubuntu ISO image to the drive in the GMKtec NucBox G3. Unless you want to use it as a Ubuntu installer.
If you want to install Ubuntu to the drive in the GMKtec NucBox G3 and use it as an operating system, then write the ISO to a USB memory stick, boot into it and select Install Ubuntu and direct the installer to write to the drive in the GMKtec NucBox G3.
By the way we can also use Startup Disk Creator to create Ubuntu Try/Live/Install version of Ubuntu.
Regards
… were his last words. Read the part about removable media. 
That’s where this is most relevant. But I can’t do more than drive the point home. Consider yourself extra thoroughly warned.
I think this much is clear and OP hasn’t done that.
That’s probably just the installer’s ESP. Do the verification steps outlined above. If everything checks out and it still doesn’t work, it’s probably like @celticwarrior said.
Seeing ESP as a NVMe drive does not sound correct.
I have internal NVMe drive, HDD as sda and if I plug in my external NVMe drive it is sdb. The USB adapter converts it from being seen as NVMe to SSD.
Samsung SSD 980 1TB sdb 931.5G
├─sdb1 vfat 512M ESP-SSK EFI System Partition F799-68A5
├─sdb2 ext4 44.9G resolute-ssk resolute-ssk 4577c708-88cd-4494-871d-0398ed15cbf1
├─sdb3 ext4 44.9G debian-ssk debian c39a230c-b91b-422b-ba80-bbc10c461b64
├─sdb6 ext4 251.1G data-ssk data-ssk e949582d-a9e6-4409-a36b-a360aa570924