Godot 4 Area2D not detecting hits? 6 reasons area_entered isn't firing

You connected area_entered, you can see the two areas overlapping in the editor, and nothing happens. This is the single most common Godot 4 combat bug, and it's almost always one of these six things. Work down the list — they're ordered by how often they're the culprit.

1. monitoring is off (or the wrong area is monitoring)

An Area2D only detects others when monitoring = true. And detection has a direction: the scanner needs monitoring; the thing being found needs monitorable. If both areas monitor each other you get double hits; if neither does, you get silence.

# the attacker scans, doesn't need to be found:
hitbox.monitoring = true
hitbox.monitorable = false
# the target is found, doesn't scan:
hurtbox.monitoring = false
hurtbox.monitorable = true

2. Layers and masks don't line up (the classic)

collision_layer is what you are; collision_mask is what you look for. For A to detect B, A's mask must include B's layer. Same number in both layer fields with empty masks = they never see each other.

# hurtbox exists on layer 3:
hurtbox.collision_layer = 0
hurtbox.set_collision_layer_value(3, true)
hurtbox.collision_mask = 0
# hitbox looks for layer 3:
hitbox.collision_layer = 0
hitbox.set_collision_mask_value(3, true)

Check this in code, not just the inspector — a parent scene or tween can overwrite layer bits at runtime and the panel won't show it.

3. There's no enabled CollisionShape2D

An Area2D with no shape (or a shape whose disabled is true, or whose shape resource is null) has nothing to collide with. It fails silently — no error, no warning.

var cs := hitbox.get_node("CollisionShape2D")
assert(cs.shape != null and not cs.disabled, "hitbox shape missing/disabled")

A frequent trap: calling cs.disabled = true to "turn off" an attack and forgetting to flip it back before the next swing.

4. The signal is connected to the wrong node

area_entered fires on the area that's doing the monitoring. If you connected the signal on the hurtbox but the hurtbox has monitoring = false (correct, per #1), the callback never runs. Connect area_entered on the monitoring area, or use body_entered if the other side is a CharacterBody2D/StaticBody2D rather than an Area2D.

hitbox.area_entered.connect(_on_hit)   # hitbox monitors, so it emits

Mixing up area_entered (Area↔Area) and body_entered (Area↔Body) is its own silent no-op — pick the one that matches what the other node actually is.

5. The hit started already overlapping (the melee trap)

area_entered only fires the frame two areas begin overlapping. If your hitbox turns on while it's already sitting on top of the target — extremely common for a melee swing that activates mid-contact — the signal never fires and the hit is lost. Scan what's already inside when you activate:

func activate() -> void:
    monitoring = true
    for area in get_overlapping_areas():
        _on_hit(area)

Note get_overlapping_areas() is only accurate after at least one physics frame of monitoring — if you enable and scan in the same frame, call await get_tree().physics_frame first.

6. Physics is paused or the node is disabled

If the area's process_mode is PROCESS_MODE_DISABLED, or the tree is paused and the node doesn't have PROCESS_MODE_ALWAYS, monitoring quietly stops. This bites during hit-stop / slow-motion, when you drop Engine.time_scale or pause the tree for feel.

# keep the hitbox live through a pause used for hit-stop:
hitbox.process_mode = Node.PROCESS_MODE_ALWAYS

The fast way to never hit this again

Every bug above comes from the same place: Area2D gives you the raw primitive and makes you wire the rules — direction, layers, shapes, overlap-on-activate, pause behavior — by hand, with no errors when you get it wrong. If you'd rather drop in two nodes that already handle all six, that's exactly what Saltmire Hitbox is: Hitbox2D / Hurtbox2D with zero layer setup, correct monitoring out of the box, and the melee overlap case handled for you.