In case of error 'Cannot load file or assembly 'AlphaVSS.x64.dll'' (...) 'or one of its dependencies. The specified file could not be found.' Xopero agent needs to be reinstalled.
The problem is caused by missing file(s):
Go to Control Panel> Programs> Uninstall a program
In the list, find Xopero and select the 'Uninstall/Change' option.
In the first window, click 'Next', then the 'Repair' option.