This issue is happening on the server script of a function that displays a message to another user, which therefore requires filtering. However when it gets to this line it throws out the error:
Unable to cast value to Object, Line 9
Script:
local onRecievingWarning = game.ReplicatedStorage.FilterWarning
onRecievingWarning.OnServerEvent:connect(function(player, message, victim)
print("Triggered!")
player = victim
print(player) --Used to make sure the I didn't mess up the order on the client side
local filteredText = game:GetService("Chat"):FilterStringForBroadcast(player, message)
local warngooey = game.ReplicatedStorage:WaitForChild("TPSWarnGUI"):Clone()
warngooey.Enabled = true
warngooey.LoginForm.Rsn.Text = filteredText
warngooey.Parent = game.Players[player].PlayerGui
wait(3)
game.Players[player].PlayerGui.TPSWarnGUI:Destroy()
end)

4 comments
i guess you could try without the wait for child
You have mixed up the order for FilterStringForBroadcast, it needs the string message then the player.
Still getting the error
Are you sending the player object on the client side?