ArchiveFolder.cs

private static void ArchiveFolder(string folderToArchive, string archivedFile)
{
    Uri folderToArchiveUri = new Uri(folderToArchive);

    var filesToArchive = Directory.EnumerateFiles(folderToArchive, "*.*", SearchOption.AllDirectories);
    using (var fs = new FileStream(archivedFile, FileMode.Create, FileAccess.ReadWrite))
    {
        using (var archive = new ZipArchive(fs, ZipArchiveMode.Create))
        {
            filesToArchive
                .ToList()
                .ForEach(
                    file =>
                    {
                        var fileName = Path.GetFileName(file);
                        archive.CreateEntryFromFile(file, fileName);
                    });
        }
    }
}