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A device attached to the system is not functioning

Symptoms

Backup fails with the error: "A device attached to the system is not functioning."

Troubleshooting Steps

Step 1: Check Volume Tracker Logs

Check the Volume tracker logs located in:

C:\ProgramData\Acronis\VolumeTrackerLogs

Step 2: Identify the Error Code

Look for one of the following error codes in the logs:

  • 0x235000b = VOLUME_LOCK_NOT_DETECTED → Follow Solution 1

  • 0x235001f = VOLUME_SNAPSHOT_FILTER_NOT_FOUND → Follow Solution 1 or Solution 2

Solution 1: Restart and Disable CBT

  1. Restart the machine after the backup failure

  2. Disable Changed Block Tracking (CBT) on the affected machine

  3. Retry the backup

Solution 2: Registry Fix

Warning: Editing the Windows Registry can cause system issues if done incorrectly. Proceed with caution and create a registry backup before making changes.

Steps

  1. Open Windows Registry Editor: Click Start, search for regedit.exe, and press Enter

  2. Navigate to:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{533c5b84-ec70-11d2-9505-00c04f79deaf}

  3. Check if fltsrv is present in the UpperFilters value

  4. If fltsrv is missing, add this data to the value

  5. Restart the machine and retry the backup

If the issue persists after trying both solutions, contact Soteria support for further assistance.