Comment 28 for bug 1153661

You can manually fix both /etc/crypttab and /etc/fstab, either using the correct UUID or using the partion identifier (e.g. /dev/sda3). What I did to fix the mentioned error message is editing /etc/rc.conf and adding a `wait 1` before the return 0. This instructs the init demon to wait a second before resuming boot, this should give it enough time to initialise the cryptswap. You might want to increase the time, based on your system's io speed.

If you want to go to a plain (none-encrypted) swap, you can create it on the terminal with
    sudo mkswap <path to partion>
e.g.
    sudo mkswap /dev/sda3

Be aware this command destroys the content of that partition! The command will also display the UUID of the newly created swap partition, so you can update your fstab accordingly.