FVE_E_AD_INVALID_DATASIZE (0X8031000C) – Fix BitLocker AD sync error

Why the error shows up – and how to fix it

Had a client last month – a dental clinic – their entire fleet of laptops started throwing this error after a forced domain join reimage. The short version: Active Directory holds a BitLocker recovery object for each drive that’s backed up. If that object’s data size doesn’t match what Windows expects, you get FVE_E_AD_INVALID_DATASIZE (0X8031000C). Most of the time, it’s not a disaster – just a messy sync.

1. Corrupted or truncated recovery data in AD – most common cause

The usual trigger: someone (or a script) wrote a partial recovery key to AD, or the AD schema extends wrong. Older domain controllers with Windows Server 2008 R2 still running AD schema version 47 can mangle the data size field.

Fix: Delete and re-backup the recovery information

1. On the affected Windows machine, open an elevated PowerShell prompt.
2. Check the current recovery key protector: Get-BitLockerVolume -MountPoint C: | fl * – note the KeyProtector ID.
3. Remove the AD backup: Remove-BitLockerKeyProtector -MountPoint C: -KeyProtectorId ""
4. Add a fresh one: Backup-BitLockerKeyProtector -MountPoint C: -KeyProtectorId ""
5. Wait a couple hours for AD replication, then check event log: Event ID 845 (BitLocker recovery information was written to Active Directory). That should show success.

If you can’t remove the protector because the drive is fully locked, boot from a WinPE USB that has BitLocker PowerShell module or use manage-bde:

manage-bde -protectors -disable C:

That turns off protection temporarily – reboot once to apply. Then run the steps above.

2. Group policy forcing a recovery size that AD can’t store

Windows 10 1809 and newer default to storing recovery keys in AD as a 48-digit numeric password. But if someone tweaked group policy under Computer Configuration → Administrative Templates → Windows Components → BitLocker Drive Encryption → Choose how BitLocker-protected OS drives can be recovered to include a 256-byte recovery package – and your domain functional level is lower than Windows Server 2012 – AD can’t hold it.

Fix: Change or disable the recovery data size in GPO

1. Open Group Policy Management Console on your DC.
2. Edit the policy applied to the affected machines.
3. Go to the same path above, set Require BitLocker backup to AD DS to Enabled.
4. Under Key Recovery Directory Services Options, choose Store recovery keys only – not “recovery keys and key packages”.
5. Run gpupdate /force on the client, then repeat the re-backup steps from fix #1.

If you must store the recovery package (e.g., for forensic reasons), upgrade your domain functional level to at least Windows Server 2012. No way around that.

3. Multiple recovery objects for the same volume – the hidden duplicate

Here’s a sneaky one: AD sometimes creates multiple child objects under CN=BitLocker Recovery Information for the same volume. Each object has a different size because one got truncated during replication. Windows reads the first one it finds – if it’s the wrong size, you get this error.

Fix: Clean up duplicate AD objects

1. Open ADSI Edit on a domain controller. Connect to the Configuration partition (or Domain partition – depends on your schema).
2. Navigate to: CN=System,CN=BitLocker Recovery Information
3. Find objects where the msFVE-RecoveryInformation attribute is present and msFVE-VolumeGuid matches your drive’s volume GUID (get it from manage-bde -protectors -get C:).
4. Delete all but the most recent one (check whenCreated).
5. Run Backup-BitLockerKeyProtector again on the client to recreate a clean object.

I’ve seen this happen when a laptop got restored from a backup that included a stale AD registration – the new backup added a second object. Deleting the old one fixed it instantly.

Quick-reference summary table