var guiDb = new MongoClient("mongodb://server1:27017/GridFSTest").GetServer().GetDatabase("GridFSTest");
var fs = guiDb.GetGridFS(new MongoGridFSSettings() { Root = "TestArea" });
var allFiles = fs.FindAll().ToList();

var server = new MongoClient("mongodb://server2:27017/GridFSTestTracker").GetServer().GetDatabase("GridFSTest");

var gridfs = server.GetGridFS(new MongoGridFSSettings()
{
	Root = "TestArea"
});

foreach (var file in allFiles)
{
	gridfs.Upload(file.OpenRead(), file.Name, new MongoGridFSCreateOptions { Id = file.Id, ContentType = file.ContentType, UploadDate = DateTime.Now, Metadata = file.Metadata }); // This row throws the exception
}