Attempt to index nil with 'WaitForChild'

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#1

I encountered the following error: Try to index null using “WaitForChild”. When I pass an HUD (GUI Interface) argument, the server defines the given argument, but when I pass it to the client, I get this error (in the header) because the value of the passed argument becomes nil:
Снимок экрана 2025-01-04 154740

Снимок экрана 2025-01-04 154755
Снимок экрана 2025-01-04 1547551296×124 26.3 KB

Printing from the server (argument - GUI - HUD):
Снимок экрана 2025-01-04 155325
Снимок экрана 2025-01-04 155325725×16 3.32 KB

#2

Can you please provide the code you are using?

#3 
--server
function ActionService:notificationPassport(player, proxPrompt, whotriggred)
	local player_pass = game.Players:GetPlayerFromCharacter(proxPrompt.Parent)
	local PassportGui = whotriggred.PlayerGui:WaitForChild("ActionsGui").Passport
	local HUD = player_pass.PlayerGui:WaitForChild("HUD")
	print(player, player_pass, whotriggred, PassportGui, HUD)
	self.Client.Passport:Fire(player, player_pass, whotriggred, PassportGui, HUD)
end

function ActionService:KnitInit()
end

function ActionService:KnitStart()
	game.Players.PlayerAdded:Connect(function(plr)
		plr.CharacterAdded:Connect(function(char)
			local hint = script.BillboardGui:Clone()
			hint.Parent = char
			local proxPrompt = script.ProximityPrompt:Clone()
			proxPrompt.Parent = char
			proxPrompt.Triggered:Connect(function(player)
				if proxPrompt.Parent ~= player.Character then
					local whotriggered = player
					self.Client.HintInteraction:Fire(player, whotriggered, proxPrompt, hint)
				end
			end)
		end)
	end)
end

--client
ActionService.HintInteraction:Connect(function(whotriggred, proxPrompt, hint)
	for _, plr in pairs(Players) do
		ActionsBillboardGUI.Adornee = proxPrompt.Parent
	end
	proxPrompt.Enabled = false
	hint.Enabled = false
	ActionsBillboardGUI.Enabled = true

	ActionsBillboardGUI.ActionsMain.CloseButton.Activated:Connect(function()
		proxPrompt.Enabled = true
		hint.Enabled = true
		ActionsBillboardGUI.Enabled = false
	end)

	for i,v in pairs(ActionsBillboardGUI.ActionsMain.Documents.ActionsScroll:GetChildren()) do
		if v:IsA("GuiButton") then
			v.Activated:Connect(function()
				if v.Name == "Passport" then
					ActionController:notificationPassport(proxPrompt, whotriggred)

					ActionService.Passport:Connect(function(player_pass, whotriggr, PassportGui, HUD)
						print(player_pass, HUD, whotriggr, PassportGui)
						local Buttons = HUD:WaitForChild("Announce3", 10).Answers
						local yes
						local no
						yes = Buttons.Yes.Activated:Connect(function()
							yes:Disconnect()
							no:Disconnect()
							HUD:WaitForChild("Announce3", 10):Destroy()
							task.wait(0.01)
							PassportGui.Title.Text = "PASSPORT ["..player_pass.Name.."]"
							PassportGui.LabelsInfo.NumDoc.Text = "2024 "..player_pass.UserId
							PassportGui.LabelsInfo.NamePlr.Text = player_pass:WaitForChild("MainPlayer"):WaitForChild("NamePass").Value
							PassportGui.LabelsInfo.Surname.Text = player_pass.MainPlayer.SurnamePass.Value
							PassportGui.LabelsInfo.PlaceDay.Text = player_pass.MainPlayer.BirthPlace.Value
							PassportGui.LabelsInfo.Gender.Text = player_pass.MainPlayer.Gender.Value
							PassportGui.LabelsInfo.ArmyTicket.Text = player_pass.MainPlayer.ArmyTicket.Value
							PassportGui.LabelsInfo.Law.Text = player_pass.MainPlayer.Lawabiding.Value
							PassportGui.Icon.Image = "rbxthumb://type=AvatarHeadShot&id=" ..player_pass.UserId.. "&w=420&h=420"
							PassportGui.Visible = true
						end)
						no = Buttons.No.Activated:Connect(function()
							yes:Disconnect()
							no:Disconnect()
							HUD:WaitForChild("Announce3", 10):Destroy()
						end)
					end)

					local PassportGui = whotriggred.PlayerGui:WaitForChild("ActionsGui").Passport

					PassportGui.CloseButton.Activated:Connect(function()
						PassportGui.Visible = false
					end)
				end
			end)
		end
	end
end)

Only all this code is written in the Knit module