I’m installing the currently latest plain vanilla Qubes 4.2 from a USB drive. In the boot menu I selected “check install media and install Qubes” and the check step is failing with the attached message that only flashes for a fraction of a second and then leaves me on a black screen.
Installing Qubes from this USB drive generally works though and the ISO file passed the checksum test before copying it onto the drive.
I think it’s unlikely something is actually corrupted on the drive but I’d like to understand what is being tested and what the error message means.
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You are not the only one who has gotten this error.
Workaround, I believe, was, Re-Format the USB to be blank.
Write Qubes to the USB drive again.
If that does not work.
Please reply with how you wrote Qubes to the USB stick.
Exactly what causes this, I dunno.
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The weird thing is that I’m getting this error but installation works fine (I installed Qubes about 6 times in the last few days because of some unrelated issue 
so I can say it works quite reliable), so I really don’t have any reason to “fix” this issue.
I created the USB drive via dd on Debian from the original ISO that I downloaded from the Qubes website.
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What do the commands systemctl status checkisomd5@dev-sda.service and journalctl -xeu checkisomd5@dev-sda.service print for their outputs?
On what system and how exactly do you want me to run that? The system on which I created the drive? The one that I just freshly installed with that drive? Dom0 or what?
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Looking at my Qubes OS 4.2.4 GRUB menu, the first option is Troubleshooting - verbose boot and install Qubes OS R4.2.4, then after initializing that, you can open a TTY2 terminal using the Ctrl + Alt + F2 keyboard shortcut. If this GRUB option is not available on your installation medium, try the option you used to successfully install Qubes OS and inputting the keyboard shortcut there instead.
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How interesting!
It suggests an error in the USB data restricted to a place where it does not affect either the installation process or the result of installation… or a difference in the hardware use between the test and the installation which gives reproducible data errors in one but not the other.
If you are interested, there is a test to find where on your key are the error(s) seen, in this fine post by @apparatus :
https://forum.qubes-os.org/t/an-unknown-error-ocurred-during-installation-on-empty-partition/28811/4
You will need to run the command on a machine where you have both access to the full USB device, and the original good iso file. Change ‘/dev/sdd’ to match the device of your USB key.
If the output is impossibly long, the following post shows use of head and tail to cut it down.
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Great idea. I connected my USB drive (the entire 30GB device) to the app qube that has the iso file and then ran this:
user@myqube:~/Downloads$ sudo cmp -n $(stat -c %s Qubes-R4.2.4-x86_64.iso) -l Qubes-R4.2.4-x86_64.iso /dev/xvdo | gawk '{printf "%08X %02X %02X\n", $1-1, strtonum(0$2), strtonum(0$3)}' | head
00000210 36 3A
00000211 7D 7E
00000212 88 ED
00000213 34 58
00000220 37 FF
00000221 8B 23
00000222 D8 B7
00000223 00 03
00000230 F8 C0
00000231 8A 23
user@myqube:~/Downloads$ sudo cmp -n $(stat -c %s Qubes-R4.2.4-x86_64.iso) -l Qubes-R4.2.4-x86_64.iso /dev/xvdo | gawk '{printf "%08X %02X %02X\n", $1-1, strtonum(0$2), strtonum(0$3)}' | tail
00000212 88 ED
00000213 34 58
00000220 37 FF
00000221 8B 23
00000222 D8 B7
00000223 00 03
00000230 F8 C0
00000231 8A 23
00000232 D8 B7
00000233 00 03
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Wow!
I don’t know what it means, but it seems there is a tiny amount of change, right at the start of the disk. Weird and intriguing. It’s the area that should have the least wear, I think, but not an expert.
I wonder if there are any useful diagnostic tools, to get more of an idea what’s going on… a non-destructive badblocks, maybe?
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