Cannot mount LUKS encrypted USB on boot after 12.10 upgrade

Solution 1:

I had the issue that a previously mountable thing in 12.04 would not mount in 14.04 and it turned out to be a bug. The manual fix was to

$ sudo apt-get install cryptsetup

As this package does not get installed by default, but is required for mounting encrypted volumes. The error I was getting, for reference was:

Error unlocking /dev/sdl1: Error spawning command-line `cryptsetup luksOpen "/dev/sdl1" "luks-b5479205-958b-43ad-9b73-nnnnnnnnnn" ': Failed to execute child process "cryptsetup" (No such file or directory) (g-exec-error-quark, 8)

Solution 2:

To have Gnome's "udisks2" mount it automatically with a GUI asking for the crypt password, you need to simply not have any mention of it in your fstab and crypttab.

udisks will automatically set up the mapping in /dev/mapper/luks-xxxx, and try to mount it under /media/[username]/[label]

If you insist on using an entry in your fstab, you have to make sure the luks mapping is set up before the system is trying to mount it.