Error "the given key was not present" when trying to backup Hyper-V

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1

Hi
I am trying to backup Virtual Machine in Hyper-V (Windows server 2016)
When I start the backup, I get exception error:
"the given key was not presented in the dictionary"
is there any special setting for Hyper-V ?
I Tried to reinstall DUPLICATI, got the same problem.

Thanks

the debug information is :
Failed while executing “Backup” with id: 2

System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary. at System.ThrowHelper.ThrowKeyNotFoundException() at System.Collections.Generic.Dictionary2.get_Item(TKey key) at Duplicati.Library.Snapshots.HyperVUtility.QueryHyperVGuestsInfo(Boolean bIncludePaths) at Duplicati.Library.Modules.Builtin.HyperVOptions.RealParseSourcePaths(String[]& paths, String& filter, Dictionary2 commandlineOptions) at Duplicati.Library.Modules.Builtin.HyperVOptions.ParseSourcePaths(String[]& paths, String& filter, Dictionary2 commandlineOptions) at Duplicati.Library.Main.Controller.SetupCommonOptions(ISetCommonOptions result, String[]& paths, IFilter& filter) at Duplicati.Library.Main.Controller.RunAction[T](T result, String[]& paths, IFilter& filter, Action1 method) at Duplicati.Library.Main.Controller.Backup(String[] inputsources, IFilter filter) at Duplicati.Server.Runner.Run(IRunnerData data, Boolean fromQueue)