Redis::CommandError: ERR wrong number of arguments for 'hset' command in ruby 2.7 and rails 6.1.3

Redis server v=5.0.3

target_servers.each do |server|   ls = Redis.new(host: server, port: 1111, db: 1)   if ls      ls.pipelined do        host.keys.sort.each do |hostname|          ls.hset(mk, *host[hostname].flatten)        end #loop      end # pipelined    end #ifend

When we run this code it throws below error -Redis::CommandError: ERR wrong number of arguments for 'hset' command