My iMac has a SSD and a HDD. The OS is installed on the SSD.

I performed a clean installation of Mountain Lion to the SSD, and cloned my SSD using a backup from my Time Capsule in OS X Recovery.

System Preferences show that FileVault is not enabled.

When I follow the routine to enable FileVault, after the iMac reboots it gives me the following error:

There was a problem enabling FileVault. Problems were encountered with the disk “Crucial M4 SSD”. Please turn off FileVault, verify and (if necessary) repair the disk with Disk Utility, and try enabling FileVault again.

I have verified and repaired the disks in Disk Utility. I used Disk Utility in OS X Recovery. Here I was unable to unlock the volume on the SSD with Disk Utility, so instead I used Terminal to unlock the volume. After the unlocked volume appeared in Disk Utility I was able to verify and repair the disk, but I still got the above error.

Results in Terminal:

  • when trying to decrypt the volume, I am told that that the volume is not encrypted
  • when trying to encrypt the volume, I am told that the volume is already encrypted

– very confusing :)

Denniss-iMac:~ dennis$ diskutil coreStorage decryptVolume 4FDED44E-EC4B-4B11-9FF5-9C958BD8CEAB
Error beginning CoreStorage Logical Volume decryption: The target Core Storage volume is not encrypted (-69755)


Denniss-iMac:~ dennis$ diskutil coreStorage encryptVolume 4FDED44E-EC4B-4B11-9FF5-9C958BD8CEAB
New passphrase for existing volume:
Confirm new passphrase:
Started CoreStorage operation on disk2 Crucial M4 SSD
Error: -69696: The target Core Storage volume is already encrypted


How can I enable FileVault on my iMac?

Is there a way to reset the partition without having to reinstall and reconfigure my system?

coreStorage world

Denniss-iMac:~ dennis$ diskutil coreStorage list
CoreStorage logical volume groups (2 found)
+-- Logical Volume Group 52C795EE-D034-4F54-9691-EF6D04AD5FF9
|   =========================================================
|   Name:         Crucial M4 SSD
|   Size:         255200755712 B (255.2 GB)
|   Free Space:   16777216 B (16.8 MB)
|   |
|   +-< Physical Volume AB27C53B-03C1-481D-9E02-B21DA84AE0F4
|   |   ----------------------------------------------------
|   |   Index:    0
|   |   Disk:     disk0s2
|   |   Status:   Online
|   |   Size:     255200755712 B (255.2 GB)
|   |
|   +-> Logical Volume Family BB92E15C-2063-4F56-99EB-5AD588AECDBB
|       ----------------------------------------------------------
|       Encryption Status:       Unlocked
|       Encryption Type:         None
|       Conversion Status:       Failed
|       Conversion Direction:    backward
|       Has Encrypted Extents:   Yes
|       Fully Secure:            No
|       Passphrase Required:     No
|       |
|       +-> Logical Volume 4FDED44E-EC4B-4B11-9FF5-9C958BD8CEAB
|           ---------------------------------------------------
|           Disk:               disk2
|           Status:             Online
|           Size (Total):       254865207296 B (254.9 GB)
|           Size (Converted):   -none-
|           Revertible:         Yes (unlock and decryption required)
|           LV Name:            Crucial M4 SSD
|           Volume Name:        Crucial M4 SSD
|           Content Hint:       Apple_HFS
+-- Logical Volume Group F0D53CC0-68D7-44FA-B2F9-0874A4FD181D
    Name:         Storage
    Size:         999860912128 B (999.9 GB)
    Free Space:   0 B (0 B)
    +-< Physical Volume BFD4B09C-0CE5-40B4-BB3D-9C7E96589573
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk1s2
    |   Status:   Online
    |   Size:     999860912128 B (999.9 GB)
    +-> Logical Volume Family B86F5A3A-C642-4956-8D21-B724CFDC3028
        Encryption Status:       Unlocked
        Encryption Type:         AES-XTS
        Conversion Status:       NoConversion
        Conversion Direction:    -none-
        Has Encrypted Extents:   Yes
        Fully Secure:            Yes
        Passphrase Required:     Yes
        +-> Logical Volume 97EDE534-A8B0-494B-8D1F-C79D136C8327
            Disk:               disk3
            Status:             Online
            Size (Total):       999709908992 B (999.7 GB)
            Size (Converted):   -none-
            Revertible:         No
            LV Name:            Storage
            Volume Name:        Storage
            Content Hint:       Apple_HFS

Similar reports of problems:

A screenshot of the errors when I try to enable FileValut: FileVault Errors

  • Boot into single user mode and run fsck -f and tell us what the results are.
    – Matt
    Commented Aug 9, 2012 at 9:36
  • After fsck has been checking multiple items, the result is The volume Crucial M4 SSD appears to be OK.
    – dhrm
    Commented Aug 9, 2012 at 16:30
  • Have you by any chance cloned the SSD from your previous computer using something like SuperDuper? Commented Aug 11, 2012 at 23:08
  • No, I "cloned" my SSD using a backup from my Time Capsule in the OS X Recovery.
    – dhrm
    Commented Aug 12, 2012 at 7:38

1 Answer 1



Review System Preferences

Create another user.

Log in as that user.

Use the Security & Privacy pane of System Preferences. In the FileVault tab, click Enable Users… then in the sheet, ensure that all required users are enabled.


System Preferences may show that FileVault is enabled, with a recovery key, when there is encryption with Core Storage, but neither FileVault 2 nor a recovery key. I reported this bug to Apple a while ago.

Similarly, but not the same bug:

  • I assume that System Preferences may show FileVault disabled on a system where most elements of FileVault are enabled.

Thorough application of Disk Utility

Ensure that the utility is applied:

  • to the logical volume group, which appears to contain the logical volume.

(Where Core Storage is used, Disk Utility in 10.8 can not show the physical disk.)

If you select the LV alone, then verification will omit the partition map.


Conversion Status: Failed

If encryption was applied when the volume was created (typically: erasure with Disk Utility) then:

  • there was no conversion forward
  • conversion backward can not begin.

Conversion Direction: backward

This implies that:

  • recently, conversion backward did begin
  • previously, the logical volume was the result of conversion forward (not the result of erasure with Disk Utility).

diskutil coreStorage encryptVolume 4FDED44E-EC4B-4B11-9FF5-9C958BD8CEAB

That could apply if logical volume 4FDED44E-EC4B-4B11-9FF5-9C958BD8CEAB was not encrypted.

As the LV is already encrypted, the response from diskutil is correct.

The question in Apple Support Communities

From the opening poster:

Does the resolution there in ASC, the bounty here in Ask Different, mean that Dennis continues to seek a more detailed answer, a better resolution?

Code -69755

-69755 appears in another discussion:

Interpreting the failure

Pessimistically but realistically:

  • a failure to convert – with conversion of nothing – may indicate media failure, possibly in or around the area occupied by the extents file.

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