I tested it and it should not happen with new version of cfa 0.6.1. Michal - I see potential problem in functionality that Import does not clear old ones, just delete_by ip address, but does not clear old hosts. I will try to reproduce it on my machine, but it works for me. My minimal testing client looks like: pepa:/tmp # cat test.rb require "yast" Yast.import "Host" Yast.import "Wizard" Yast::Wizard.OpenDialog(Yast::Term.new(:HBox)) export = Yast::Host.Export export["hosts"] = { "127.0.0.1" => ["localhost"], "127.0.0.2" => ["localhost2 localhost.backup"] } Yast::Host.Import(export) Yast::Host.Write Yast::Wizard.CloseDialog I have no idea what more is needed for reproducing it. Michal - from log also this part looks a bit strange, but not sure if it is root of issue: 2017-07-09 11:43:20 <2> admin(4095) [Ruby] yast/builtins.rb:586 tostring builtin called on wrong type Class