Comment 5 for bug 1852521

I did some investigation. It seems that in /etc/crypttab, the third column of the encrypted disk does points to a key file, and the content of the key file is the passphrase.

Not sure why this is created, but I've previously used Ubuntu's disk utility to change the passphrase of my root disk, maybe this is related.

Anyway, I changed the third column to `none` and manually remove the key file. Finally, I execute update-initramfs again and now the system become bootable even with the latest kernel.