Comment 25 for bug 1153661

More info, hope it helps:

With the default setup script with no changes, I get the error message on boot and gparted shows /dev/sda5 as "unknown", not "linux-swap". This is before reverting to unencrypted swap. After uncommenting the UUID line and removing the cryptswap1 line in /etc/fstab, removing the entry in /etc/crpyttab, and rebooting, I get a different error on boot saying the disk at UUID=..number.. can't be mounted, instead of the /dev/mapper/cryptswap1 error. Reformatting swap and rebooting fixes this.

With offset=8, I still get the /dev/mapper/cryptswap1 error on boot, but gparted shows /dev/sda5 as "linux-swap", not "unknown". Reverting /etc/fstab and /etc/crypttab as above and rebooting results in no error and a working unencrypted swap with no need to reformat it.

I tried offset=16 with the same results as offset=8. Also tried replacing UUID with $swap in the script, with no offset, offset=8 and offset=16, with no luck.