Godot 4 gotchas when you are following a Godot 3 tutorial

Most Godot tutorials online are still Godot 3, and the API moved enough between versions that following one in Godot 4 produces confusing errors.

The changes that trip people up most:

• KinematicBody2D is now CharacterBody2D, and move_and_slide() takes no arguments — set velocity first
• yield became await
• export var x became @export var x
• onready became @onready
• Tweens are objects now — create_tween() instead of a Tween node
• instance() became instantiate()

If a tutorial's code will not compile, check the upload date first. Anything before 2023 is almost certainly Godot 3.