godot-4-migration

Godot 4 Migration Guide

Overview

A critical guide for developers transitioning from Godot 3.x to Godot 4. This skill focuses on the major syntax changes in GDScript 2.0, the new Tween system, and export annotation updates.

When to Use This Skill

• Use when porting a Godot 3 project to Godot 4.
• Use when encountering syntax errors after upgrading.
• Use when replacing deprecated nodes (like Tween node vs create_tween).
• Use when updating export variables to @export annotations.

Key Changes

1. Annotations (@)

Godot 4 uses @ for keywords that modify behavior.

• export var x -> @export var x
• onready var y -> @onready var y
• tool -> @tool (at top of file)

2. Setters and Getters

Properties now define setters/getters inline.

Godot 3:

var health setget set_health, get_health

func set_health(value):
    health = value

Godot 4:

var health: int:
    set(value):
        health = value
        emit_signal("health_changed", health)
    get:
        return health

3. Tween System

The Tween node is deprecated. Use create_tween() in code.

Godot 3:

$Tween.interpolate_property(...)
$Tween.start()

Godot 4:

var tween = create_tween()
tween.tween_property($Sprite, "position", Vector2(100, 100), 1.0)
tween.parallel().tween_property($Sprite, "modulate: