system installation – 24.04 desktop install to USB/SSD on Raspberry Pi 4B fails

Good morning,
I’d like to run Ubuntu 24.04 from a USB connected SSD on a Raspberry Pi 4B. I’ve followed the instructions which indicate to use the Imager to install the image to the media and then boot. ubuntu.com/tutorials/how-to-install-ubuntu-desktop-on-raspberry-pi-4#2-prepare-the-sd-card I’ve examined the page ubuntu.com/tutorials/how-to-install-ubuntu-desktop-on-raspberry-pi-4#4-optional-boot-from-usb-with-an-external-ssd and meet the criteria there. (This particular Pi can boot RpiOS and Debian from a USB/SSD and I have previously run Ubuntu from SSD following the instructions at openzfs.github.io/openzfs-docs/Getting%20Started/Ubuntu/Ubuntu%2022.04%20Root%20on%20ZFS%20for%20Raspberry%20Pi.html but I prefer a plain installation at this time.)

The system comes up and I see the splash screen with the spinner. Eventually I’m presented with an (initramfs) prompt. Hitting D results in a kernel panic. Power cycling and getting bnack to the (initramfs) prompt and typing reboot seems to do nothing. this time D produces a message that the root filesystem could not be mounted.

Examining the SSD in another PC, I can see that the root filesystem has been expanded but there seems not to be a filesystem there. blkid /dev/sda2 lists nothing. cmdline.txt in the boot partition indicates that the root partition is root-LABEL=writable and the root partition was so labelled following imaging. It seems like the first boot processing broke after/during resizing the partition.

Any easy fix for this? It seems like I should label the partition and recreate the filesystem with existing contents but I cannot see a way to recreate the filesystem with the existing contents intact.

Seems like a bug and I am not familiar enough with Ubuntu to know where to look for this. It seems unlikely that I’m the first to encounter this problem. Launchpad seems like the place to look but it seems focused on packages and I don’t know which package would be involved with first boot processing.

Thanks!