Hyper-V backup completed with warning.


Hyper-V CBT library 'c:\unicbt\bin\phdcbtcm.dll' failed to load. - the specified module could not be found



  • OS : Windows 2012, Windows 2012 R2
  • Hyper-V CBT backup
  • CBT Driver version: 05/08/2015,
  • Client Version : 8.1.0-4  Client Build...: May 12 2015-19:24:56
  • CBT Driver Installed at c:\unicbt


On a new installation of Unitrends agent 8.0.0-4, after having installed the Hyper-V CBT driver successfully into C:\unicbt and upon performing a Hyper-V incremental backup, the backup completes as "yellow" and the wbps log has the error message "Hyper-V CBT library 'c:\unicbt\bin\phdcbtcm.dll' failed to load."

May 19 19:44:03 : LoadDriverCbtAppSupport::3334 Hyper-V CBT
library 'c:\unicbt\bin\phdcbtcm.dll' failed to load.
May 19 19:44:03 :    - 'LoadLibrary' call failed: 126
May 19 19:44:03 :    - Returned HRESULT = 0x8007007e
May 19 19:44:03 :    - Error text: The specified module could not be found.


The specified module that could not be found is not phdcbtcm.dll as one might think. The module c:\unicbt\bin\phdcbtcm.dll is installed on the server. The module that cannot be found is a missing dependency on the Visual C++ Redistributable Packages.  

The Visual C++ Redistributable Packages for Visual Studio 2013 (vcredist_x64.exe) must be installed on the Hyper-V server:  https://www.microsoft.com/en-us/download/details.aspx?id=40784
The Visual C++ Redistributable for Visual Studio 2012 (vcredist_x64.exe) must also be installed:  https://www.microsoft.com/en-us/download/details.aspx?id=30679


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