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BA5108: Error accessing or unlocking the BitLocker-encrypted drive

Error code Product Applies to
BA5108 BackupAssist For BackupAssist 8.4.1 or later.

Description

BackupAssist can back up to a BitLocker-encrypted destination drive, unlocking the drive before the backup using the configured key. BA5108 is recorded when BackupAssist could not access or unlock the BitLocker-encrypted destination, so the backup could not proceed.

Common causes:

  • The USB drive or volume that holds the BitLocker external/recovery key is not connected, or has been assigned a different drive letter.
  • The recovery/external key does not match the destination drive - for example the wrong disk in a rotated set is connected.
  • The drive cannot be unlocked with the configured method.

Resolution

  1. Make sure the USB volume that holds the BitLocker key is connected before the backup runs.
  2. Confirm the external/recovery key matches the destination drive for this run.
  3. Try to unlock the drive manually in Windows (BitLocker Drive Encryption control panel, or "manage-bde -unlock" from an elevated command prompt) to confirm the key and drive are correct.
  4. Re-run the backup.

Resolution 2 - Check rotated media

If you rotate BitLocker-encrypted drives, ensure the correct disk for this run is connected and that its key is available to BackupAssist.

Resolution 3 - Contact technical support

If the drive still cannot be unlocked, generate diagnostics and contact support - BackupAssist Support page.

Note on the backup report

The backup report shows: Error accessing or unlocking the Bitlocker-encrypted drive.

Last updated Created Further assistance
7th Aug 2026 7th Aug 2026 BackupAssist Support page