--- a/plugins/mod_muc_mam.lua	Tue Dec 24 00:27:44 2019 +0100
+++ b/plugins/mod_muc_mam.lua	Mon Dec 23 23:32:49 2019 +0100
@@ -357,6 +357,8 @@
 	if id then
 		schedule_cleanup(room_node);
 		stanza:add_direct_child(st.stanza("stanza-id", { xmlns = xmlns_st_id, by = self.jid, id = id }));
+	else
+		module:log("error", "Could not archive stanza: %s", err);
 	end
 end