Answer by ham for Roblox Studio: CharacterAdded is not a valid member of Players

    game.Players.PlayerAdded:Connect(function(plr) plr.CharacterAdded:Connect(function(character)        character:WaitForChild("Humanoid").Died:Connect(function(msg)        local data = { --contet of data            content = msg;            username = plr.Name;            avatar_url = "http://www.roblox.com/Thumbs/Avatar.ashx?x=100&y=100&Format=Png&userId="..plr.UserId        }        HttpService:PostAsync(webhook, HttpService:JSONEncode(data))    end)end)

the game.Players.PlayerAdded rbxscriptsignal isn't complete and the plr thing dosen't belong in plr.CharacterAdded