Revert encryption error I'm trying to revert the encryption on my disk, but Disk Utility gives me an unknown error, and from the command line, using

sudo diskutil corestorage rever UUID


It gives me this error:


  Error: -69741: The target disk isn't eligible for reversion because it wasn't created by conversion or it is not part of a simple setup of exactly one logical and one physical volume


The hard disk is encrypted by me, so I know the passphrase (which is asked soon after the command, before the error). It's the main disk, on which the OS is installed, and encrypted with FileVault 2.
I recently updated to Mountain Lion Developer Preview. I know this could be a bug, since it's a DP, but in my opinion the problem is related to the upgrade itself and it would be present even if I updated from SL to Lion or something similar.

This is part of the output of the diskutil corestorage list:

|   +-&gt; Logical Volume Family UUID
|       ----------------------------------------------------------
|       Encryption Status:       Unlocked
|       Encryption Type:         AES-XTS
|       Conversion Status:       NoConversion
|       Conversion Direction:    -none-
|       Has Encrypted Extents:   Yes
|       Fully Secure:            Yes
|       Passphrase Required:     Yes
|       |
|       +-&gt; Logical Volume UUID
|           ---------------------------------------------------
|           Disk:               disk1
|           Status:             Online
|           Size (Total):       499097100288 B (499.1 GB)
|           Size (Converted):   -none-
|           Revertible:         No
|           LV Name:            Macintosh HD
|           Volume Name:        Macintosh HD
|           Content Hint:       Apple_HFS


As you can see, it also says Revertible: No.

What should I do?
Reversibility of encryption depends on whether you converted volume to encrypted one or created encrypted volume. So if you want the process to be reversible — create disk first, then encrypt it using diskutil. From this it seems that in your case you should copy all data to another disk, erase this one (creating unencrypted partition), encrypt it and move data back.