The backup contains files that belong to another operating system

Here’s the complete latest message:

Failed: The backup contains files that belong to another operating system. Proceeding with a backup would cause the database to contain paths from two different operation systems, which is not supported. To proceed without losing remote data, delete all filesets and make sure the --no-auto-compact option is set, then run the backup again to re-use the existing data on the remote store.

Details: Duplicati.Library.Interface.UserInformationException: The backup contains files that belong to another operating system. Proceeding with a backup would cause the database to contain paths from two different operation systems, which is not supported. To proceed without losing remote data, delete all filesets and make sure the --no-auto-compact option is set, then run the backup again to re-use the existing data on the remote store.

at Duplicati.Library.Main.Operation.BackupHandler.Run(String sources, IFilter filter)

at Duplicati.Library.Main.Controller.<>c__DisplayClass17_0.<Backup>b__0(BackupResults result)

at Duplicati.Library.Main.Controller.RunAction[T](T result, String& paths, IFilter& filter, Action`1 method)