Comment 17 for bug 1867431

I do weekly backup for my VMs, so I first update/upgrade all VMs before the backup. The first two systems passed without problems (Host OS Ubuntu 20.04 on ZFS and Xubuntu 20.04 VM on ext4). The next two failed a few minutes later (Ubuntu 20.04 VM and Ubuntu Mate 20.04 VM). I restored the zfs snapshot from last week and they work again with that old version, but retries fail again.
The first two systems have libcrypt1 1:4.4.10-10ubuntu4 and the others that failed have 1:4.4.10-10ubuntu1, despite that they have been updated only a few minutes later.

System that I did not touch on Saturday still have 1:4.4.10-10ubuntu1 and they think it is the latest version according to synaptic and the same is true for the systems I restored from a snapshot of the previous Saturday, March 7.

It looks that your older upgrade from early Saturday worked, but somewhere during the morning it did fall apart.