update-initramfs can't handle encrypted swap-files

[Tymion Larsik]

OS: Ubuntu 20.04 Mate

I have an encrypted swap-file, which is working fine:

# grep cryptswap /etc/fstab
/dev/mapper/cryptswap none swap defaults 0 0
# grep cryptswap /etc/crypttab
cryptswap /cryptswapfile /dev/urandom swap,cipher=aes-xts-plain64,size=256

But everytime I update the kernel and update-initramfs is executed, an error occurs:

cryptsetup: ERROR: Couldn't resolve device /cryptswapfile
cryptsetup: WARNING: Resume target cryptswap uses a key file

And after the next reboot, the system can't load the cryptswap while booting and hangs for several minutes.

Workaround: Boot into rescue mode and wait until the loading of the cryptswapfile timeouts. Go to a shell and comment the lines in the fstab and crypttab. Execute # swapoff -a && update-initramfs -u. Now uncomment the lines in fstab and crypttab again and reboot. Your system should boot fine and you should have an encrypted swapfile.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.