ServerScriptService.Cmds.Duty:15: attempt to concatenate string with nil

game.Players.PlayerAdded:Connect(function(plr)
	plr.Chatted:Connect(function(msg)
		local args = msg:split(" ")
		local plrb = args[2]
		local duty = args[3]
		local user = game.Players:FindFirstChild(plrb)
		local user2 = game.Players:FindFirstChild(plrb)
		local Time = script.Parent.Variables.Duty.DutyTime.Value
		
		if args[1] == "-duty" then
			if duty and user then
				if Time then
					while true do
						Time = Time - 1
						user.Character.Head.Rank.Frame.Name1.Text = "("..Time.."m) - "..duty.." - "  ..duty.Name
						wait(60)
						if Time == "0" then
							user.Character.Head.Rank.Frame.Name1.Text = duty.Name
						end	
					end
				end
			end
		end
	end)
end)

At this part

user.Character.Head.Rank.Frame.Name1.Text = "("..Time.."m) - "..duty.." - "  ..duty.Name

Either Time or duty is nil. Make sure they have a string value before you combine them with strings

What do you mean? Do you mind explaining.

The values are nil, you are combining them with a string but they have no value so you cant combine them

What you mean by values are nil? the dutytime is set.