arcserve-KB : Unable to enable CBT (Change Block Tracking)

Last Update: 2016-11-23 17:15:07 UTC

Error Message: 

The backup failed because changed block tracking cannot be enabled on the specified virtual machine.


Ca ARCserve Host based VM backup R16 Update 7

Operating system : Windows 2008 R2 64 bit

Ca ARCserve D2d: R16 Update 7

Preflight check fails with the error 'Unable to enable CBT' and If we run 'Full' or 'Incremental' backups it would fail immediately with the error, 'The backup failed because changed block tracking cannot be enabled on the specified virtual machine'


IMPORTANT: This article contains information about modifying the registry.Before you modify the registry, make sure to create back up of the registry and ensure that you understand how to restore the registry if a problem may occur.

For more information about how to back up, restore, and edit the registry, please review the relevant Microsoft Knowledge Base articles on

1. The VM Hardware Version should be 7 or above.

2. It should not be on RDM( RAW DEVICE MAPPING) Disk.

3. VMware tools should be up-to-date.

4. If you still have the above error take a look at, VMwaremanager.log  on the Proxy machine. It would be located under (C:\Program files\CA\ARCserve D2D\Logs) . 

2013-01-11 18:30:52,321 [DEBUG] V2P_Export.CheckAndEnableCBT – Attempting to enable CBT for VM VM-Regal with UUID 503f5214-810f-0ad2-4ab6-be96fe7a1b06

2013-01-11 18:30:52,712 [DEBUG] CAVMwareVirtualInfrastructureManager.CheckAndEnableCBT - CBT is already enabled. Returning true

2013-01-11 18:30:52,712 [ERROR] CAVMwareVirtualInfrastructureManager.CheckForFullDiskKey - Find create specified Key

2013-01-11 18:30:52,712 [DEBUG]CAVMwareVirtualInfrastructureManager.CheckAndEnableCBT - Unable to determine the state of the full disk backup key.

2013-01-11 18:30:52,712 [DEBUG] V2P_Export.CheckAndEnableCBT - Returning 0 from CheckAndEnableCBT

If you see above error then

On the proxy machine go to,

-HKLM\\Software\\CA\\CA ARCserve D2D\\AFBackupDll

-Create a KEY with the VM's UUID and under that.

-Create a string key value with name “full disk backupForFullBackup' and set the value to 0

- also check for dword ResetCBT=1 if it is not present please create and set a value 1.

How to determine the UUID of a Virtual Machine

1. Log on to Host based backup and click on nodes.

2. Right click on the node for which you need the UUID.

3. Click on Logon to D2D.

4. Once you are on D2d screen you can see the UUID as shown below.

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