Fix 0xC021000C: BitLocker Not a Data Volume Error
BitLocker says your drive isn't a data volume. Usually happens on an encrypted OS drive. Here's how to fix it quick.
What This Error Means
You're staring at error 0xC021000C when trying to manage a BitLocker drive. The full message says "The volume specified is not a data volume." This happens most often when someone tries to unlock or change a system drive (like C:) using a command meant for a secondary drive. Or when BitLocker gets confused after a Windows update.
I've seen this on Dell OptiPlex 7080s and Lenovo ThinkPads after a BIOS update or a failed recovery. The culprit here is almost always a misunderstanding of what BitLocker thinks your drive is. OS drives work differently than data drives.
Simplest Fix (30 seconds) – Check Your Command
Stop. Before you do anything else, look at what you typed. If you ran something like manage-bde -unlock D: on your C: drive, that's why you see this error. That command only works on data volumes.
For the OS drive (usually C:), use the recovery key instead. Open a command prompt as admin and run:
manage-bde -unlock C: -RecoveryPassword YOUR-48-DIGIT-KEYIf you don't have the recovery key, check your Microsoft account at account.microsoft.com/devices/recoverykey. Or check the USB drive or printout you saved when you first set up BitLocker.
If that fixes it, you're done. Move on with your day.
Moderate Fix (5 minutes) – Use the Right Tool
If the simple fix didn't work, BitLocker might be stuck thinking your drive is a data volume when it's not. Or the drive is actually a data volume that's reporting wrong. Here's how to check and fix it.
Open PowerShell as admin. Run:
Get-BitLockerVolume -MountPoint C:Look at the Protection Status and VolumeType fields. If VolumeType says "Data", that's your problem – Windows thinks it's a data drive but it's actually the OS drive.
To fix this, you need to re-protect the volume properly. First, suspend protection:
Suspend-BitLocker -MountPoint C: -RebootCount 1Then reboot. After the reboot, resume protection:
Resume-BitLocker -MountPoint C:This usually resets the volume type. If it doesn't, you might need the advanced fix below.
Advanced Fix (15+ minutes) – Decrypt and Re-Encrypt
When nothing else works, you have to decrypt and re-encrypt. This is the nuclear option. Takes time but it's the only reliable fix I've found for this error when it's persistent.
Before you start, back up all your data. I mean it. Don't skip this. A bad decryption can corrupt everything.
Open PowerShell as admin. Check protection status first:
manage-bde -status C:If it's protected, suspend it:
manage-bde -protectors -disable C:Now decrypt the drive:
manage-bde -off C:This can take a while – maybe an hour on a 256GB drive. You'll see decryption progress if you run manage-bde -status C: again.
Once it's fully decrypted (Conversion Status shows "Fully Decrypted"), reboot. Then enable BitLocker again from Control Panel – it'll detect the drive as an OS volume and set it up right this time.
Don't bother with chkdsk or SFC for this error – they don't fix the BitLocker metadata issue and just waste your time.
One More Tip
If this error shows up on a secondary drive (like a USB drive or external HDD), check if it's actually formatted as NTFS. BitLocker requires NTFS for data volumes. If it's FAT32 or exFAT, reformat it – but you'll lose the data. So move files off first.
I've also seen this on drives that were part of a Storage Spaces pool. If that's you, remove the drive from the pool before trying any of the above.
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