HyperV CBT Driver Fails to install


After installing or updating the Unitrends agent, CBT fails to install. 

As of version 10.3.1 we now have two CBT drivers. 

One is used only for Image-based backups. This is only available in version 10.3.1 or greater. This driver is digitally signed. 
The other CBT driver, which is our original driver is used to track changes with incremental backups. This driver is not digitally signed at this time.

Windows Server 2012 or greater supports a security setting called Driver Signature Enforcement. If this is enabled our CBT driver will not install. You will see the following failure in the CBT install log, or by running the install.bat from

.\Install.bat /i

SC] StartService FAILED 577:

Windows cannot verify the digital signature for this file. A recent hardware or software change might have installed a file that is signed incorrectly or damaged, or that might be malicious software from an unknown source.

ERROR - Failed to start cbt driver !!!
"Failed to install Cbt"
[SC] EnumQueryServicesStatus:OpenService FAILED 1060:

The specified service does not exist as an installed service.

"Cbt cluster service not present" 


You will need to Disable Driver Signature Enforcement from the windows boot menu which can be accessed by tapping F8 during boot.

Please see the following link for more information.


Once this has been disabled the driver can be installed. 


C:\PCBP\Win2012.dir\12-04-2015,9.0.0-6 .\Install.bat /i

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