Roblox FireServer Player Passed Twice: Fix

Roblox RemoteEvent Wrong Arguments (Player Passed Twice) – Fix

The error

Values arrive wrong in OnServerEvent / 'attempt to index nil' / argument is a Player instead of my data

What it means

RemoteEvent:FireServer(...) automatically sends the calling player as the first argument of OnServerEvent. If you also pass the player yourself, or forget the player parameter on the server, every argument shifts by one.

The fix

-- LocalScript
remote:FireServer("Sword") -- do NOT pass LocalPlayer
-- Script (server)
remote.OnServerEvent:Connect(function(player, itemName)
    if typeof(itemName) ~= "string" then return end -- validate client input
    print(player.Name, "requested", itemName)
end)

Always validate data from clients on the server; exploiters can fire remotes with anything.