COMException on FileTarget.DoCleanup

[negue]

I have many bugreports with this Exception:

Message: Error HRESULT E_FAIL has been returned from a call to a COM component. ---
System.Runtime.InteropServices.COMException (0x80004005): Error HRESULT E_FAIL has been returned from a call to a COM component.
   at Windows.Storage.StorageFolder.GetFilesAsync()
   at MetroLog.FileTarget.<docleanup>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MetroLog.Targets.FileTargetBase.<checkcleanupasync>d__25.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MetroLog.Targets.FileTargetBase.<writeasynccore>d__26.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MetroLog.Targets.Target.<writeasync>d__5.MoveNext()

Latest Nuget Version Windows Store App 8.1