Comment 15 for bug 1802617

Sorry for the spam, this is how to fix this (note it will mean your swapfile isn't encrypted anymore and I'm not sure how much of a security risk that poses).

After you've run `do-release-upgrade -d`:

1) sudo swapoff -a
2) sudo cryptsetup remove cryptswap1
3) Edit `/etc/fstab`, remove the line mentioning cryptswap1
4) Edit `/etc/crypttab `, remove the line mentioning cryptswap1
5) sudo update-initramfs -u
6) sudo update-grub
7) Reboot