Error Log 404.

local shiftspeed = 25 -- Change if you want
local mouse = game.Players.LocalPlayer:GetMouse()
local running = false


mouse.KeyDown:connect(function (key)
    key = string.lower(key)
    if string.byte(key) == 48 then
        running = true
        local keyConnection = mouse.KeyUp:connect(function (key)
            if string.byte(key) == 48 then
                running = false
            end
        end)
        game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = shiftspeed
        repeat wait () until running == false
        keyConnection:disconnect()
        game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 16
    end
end)