Comment 16 for bug 1153661

The issue arises from using UUID to identify encrypted swap space: that is not supported, as stated at section 2.3 of the cryptsetup FAQ (https://code.google.com/p/cryptsetup/wiki/FrequentlyAskedQuestions#2._Setup):

"Specifying it directly by UUID does not work, unfortunately, as the UUID is part of the swap signature and that is not visible from the outside due to the encryption and in addition changes on each reboot with this setup."

Just use disk IDs in /etc/crypttab and reboot,

$ more /etc/crypttab
cryptoswap /dev/sdaX /dev/urandom swap,cipher=aes-cbc-essiv:sha256

Bear in ming though the disk ID may change if you multiple disk in the system!