Comment 3 for bug 1874662

@Kristoffer / umeaboy - the most common failure in my experience is the WRITE to the install media (assuming your ISO was checked after download & computed valid).

For releases up to (but not including) 20.04, see

https://help.ubuntu.com/community/Installation/CDIntegrityCheck

where "Check Disc for Defects" will validate your install media (be it cd/dvd/hdd/ssd/thumb-drive/flash-card) and not where you are installing to.

You can check `dmesg` to look for squashfs errors (in a terminal if you're using 'live' installer), or in filed bug reports, where the device where the squashfs errors occurred will be your install media if you've been sent to this report. It maybe a faulty ISO, bad write to install media (what my link/CDIntegrityCheck will validate), failing/faulty device, or combination.