Change scene crash

[Helow]

Godot Version

4.2.2

Question

How to fix this error?
When I run current scene (level 1) and go thru a door with get_tree().change_scene_to_file("res://menu.tscn") it takes me to menu. Then click on ‘start’ button with get_tree().change_scene_to_file("res://scenes/level1.tscn")
but at this point then it will crash.

simplify: level1 ->door (in level1 to menu) ->start (in menu to level1) → [CRASH]

whereas, if I start from menu → start (in menu to level1) → door(in level 1 to menu) ->menu → [repeatable]
It would not crash. Can go thru door many times.

Also, how to speed up the change scene, it is slow.

[herrspaten]

What does the error message say? The time it takes to switch scenes depends on the size of the scenes. You can use background threads and a loading screen to make it more pleasent

[Helow]

Sorry, not error, the debug would not respond

[herrspaten]

Can you show the code where you are changing the scenes?

[Helow]

I changed it a little, because it suddenly has error, something to do with timer error so I added a Timer node and change from get_tree.create_timer(1) to timer.start(1) and await timer.timeout

Then it cannot read the scene.
Error was
Invalid type in function 'change_secen_to_file' in base 'SceneTree'. Cannot convert argument 1 from Object to String

and now have another error:
Cannot call method 'change_scene_to_packed' on a null value

here is the code for door:

@onready var timer = $Timer
@onready var main_screen = preload("res://menu.tscn") #changed

func _on_lever_is_active():
	#var bodies = get_overlapping_bodies()
	#for body in bodies:
		#if body.name == "Player":
	$AnimationPlayer.play("opening")
	timer.start(1)
	await timer.timeout
	$AnimationPlayer.play("opened")
	get_tree().change_scene_to_packed(main_screen) #changed
	pass # Replace with function body.


func _on_timer_timeout():
	pass # Replace with function body.

and this is for the menu (changed the level 1 → world)

@onready var StartButton = $CanvasLayer/HBoxContainer/MarginContainer/VBoxContainer/Start
@onready var SettingsButton = $CanvasLayer/HBoxContainer/MarginContainer/VBoxContainer/Settings
@onready var QuitButton = $CanvasLayer/HBoxContainer/MarginContainer/VBoxContainer/Quit


func _on_start_pressed():
	get_tree().change_scene_to_file("res://scenes/world.tscn")

func _on_settings_pressed():
	get_tree().change_scene_to_file("res://scripts/options.tscn")

func _on_quit_pressed():
	get_tree().quit()

func _on_start_mouse_entered():
	StartButton.add_theme_color_override("font_hover_color", Color("dae376"))

func _on_settings_mouse_entered():
	SettingsButton.add_theme_color_override("font_hover_color", Color("dae376"))
	
func _on_quit_mouse_entered():
	QuitButton.add_theme_color_override("font_hover_color", Color("dae376"))

[herrspaten]

@onready and preload do not make sense in a assignment. Choose either @onready and load or just preload

[Helow]

It is still getting an error
Cannot call method 'change_scene_to_packed' on a null value

code for Door:

@onready var timer = $Timer
var main_screen = preload("res://menu.tscn") #changed

func _on_lever_is_active():
	#var bodies = get_overlapping_bodies()
	#for body in bodies:
		#if body.name == "Player":
	$AnimationPlayer.play("opening")
	timer.start(1)
	await timer.timeout
	$AnimationPlayer.play("opened")
	get_tree().change_scene_to_packed(main_screen) #changed
	pass # Replace with function body.


func _on_timer_timeout():
	pass # Replace with function body.

[herrspaten]

are you sure the path to the menu.tscn is correct?

[Helow]

yes, I dragged it from the file system.

[herrspaten]

Can you print out the value of “main_screen” before you change the scene?

print("Main Screen: ", main_screen)
get_tree().change_scene_to_packed(main_screen) #changed

you can also try to replace preload with load

[pauldrewett]

You are also starting to play an animation and immediately trying to change the scene here: not saying it is the cause of your problem (I would do as @herrspaten suggested above) but this is certainly strange.

	$AnimationPlayer.play("opened")
	get_tree().change_scene_to_packed(main_screen) 

[Helow]

@herrspaten

print("Main Screen: ", main_screen)

commented out the $AnimationPlayer.play("opened")
and change to var main_screen = load("res://menu.tscn")

Still the same error, null value.

Noticed another error in debugger:

line 14 is the get_tree().change_scene_to_packed(main_screen)

Output:
Main Screen: <PackedScene#-9223372009054927648>
Main Screen: <PackedScene#-9223372009054927648>

[herrspaten]

This indicates that the scene with the script is not inside the scenetree when this is called

[Helow]

the Door node (attached is door.gd) in the world node (/scene)

note: Door is not a scene. world and menu are scenes

[herrspaten]

Do you queue_free the door at any point?

[Helow]

No, did not queue_free the door.

[Helow]

extends Area2D
managed to fix the error and crash. it may have something to do with the timer node and the var load.

Final script.

func _on_lever_is_active():
	
	$AnimationPlayer.play("opening")
	await get_tree().create_timer(1).timeout
	get_tree().change_scene_to_file("res://menu.tscn")
	pass # Replace with function body.

Thank you very much @herrspaten and @pauldrewett