In my output it states... Humanoid is not a valid member of Model
local Duplicate = script.Parent:clone()
local Object = script.Parent
local Folder = script.Parent.Parent
while true do
wait(5)
if Object.Humanoid.Health <1 then -- the problem
DuplicateOfDuplicate = Duplicate:clone()
DuplicateOfDuplicate.Parent = Folder
DuplicateOfDuplicate:makeJoints()
script.Parent:remove()
end
end

5 comments
Where is this script located?
I'm tired and don't feel like waiting for a response... but assuming this is in starterpack or something of that sort and the 'object' must be the backpack or the player, you have to get the character instead of just the player so trying doing Object = script.Parent.Character otherwise, try Object:WaitForChild("Humanoid")
@Piccolo in a zomebie
If you look inside the zombie you will not find Humanoid. it is most likely named Zombie or something like that so find what the humanoid is named and name the "Humanoid in your script, what the humanoid is named in the zombie.
maybe to = instead of <