I am experiencing this as well on a fresh install of 24.04 to a blank NVMe using the ZFS with encryption option. I see similar error messages under the password dialog when unlocking the disk. As far as I can tell things seem to work fine.
update-initramfs: Generating /boot/initrd.img-6.8.0-31-generic cryptsetup: WARNING: dm_crypt-0: couldn't determine device type, assuming default (plain). cryptsetup: WARNING: Option 'cipher' missing in crypttab for plain dm-crypt mapping dm_crypt-0. Please read /usr/share/doc/cryptsetup-initramfs/README.initramfs.gz and add the correct 'cipher' option to your crypttab(5). cryptsetup: WARNING: Option 'size' missing in crypttab for plain dm-crypt mapping dm_crypt-0. Please read /usr/share/doc/cryptsetup-initramfs/README.initramfs.gz and add the correct 'size' option to your crypttab(5). cryptsetup: WARNING: Resume target dm_crypt-0 uses a key file Ubuntu 24.04 LTS \n \l Linux 6.8.0-31-generic #31-Ubuntu SMP PREEMPT_DYNAMIC Sat Apr 20 00:40:06 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS loop0 7:0 0 4K 1 loop /snap/bare/5 loop1 7:1 0 74.2M 1 loop /snap/core22/1380 loop2 7:2 0 269.6M 1 loop /snap/firefox/4173 loop3 7:3 0 10.7M 1 loop /snap/firmware-updater/127 loop4 7:4 0 505.1M 1 loop /snap/gnome-42-2204/176 loop5 7:5 0 91.7M 1 loop /snap/gtk-common-themes/1535 loop6 7:6 0 10.3M 1 loop /snap/snap-store/1124 loop7 7:7 0 38.7M 1 loop /snap/snapd/21465 loop8 7:8 0 476K 1 loop /snap/snapd-desktop-integration/157 zd0 230:0 0 20M 0 disk └─keystore-rpool 252:0 0 4M 0 crypt /run/keystore/rpool nvme0n1 259:0 0 931.5G 0 disk ├─nvme0n1p1 259:1 0 1G 0 part /boot/efi ├─nvme0n1p2 259:2 0 2G 0 part ├─nvme0n1p3 259:3 0 8G 0 part │ └─dm_crypt-0 252:1 0 8G 0 crypt [SWAP] └─nvme0n1p4 259:4 0 920.5G 0 part -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2060947 Title: Warnings produced in apt upgrade processing triggers for initramfs- tools To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/cryptsetup/+bug/2060947/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs