Quick answer: Open the NavigationPolygon resource on the region. Set Parse Geometry → Source Group, then add your wall nodes to that group. Bake. The bake now sees walls regardless of where they live in the tree.

You bake a NavigationRegion2D and half your dungeon’s walls are ignored. Agents walk diagonally through stone. The bake source isn’t finding the wall colliders because they’re not where the parser is looking.

The Symptom

Bake produces a navmesh that ignores some walls (often TileMap-based ones). Or the navmesh covers regions that should be impassable. Agents path through walls.

The Mental Model

NavigationRegion2D bakes a NavigationPolygon resource. The polygon’s Geometry section configures:

Default Source Geometry Mode = Root Node Children only finds direct children of the NavigationRegion2D. If your walls are nested elsewhere, they’re invisible to the bake.

The Fix

Step 1: Set Source Geometry Mode = Group With Children. Open the NavigationPolygon. Geometry → Source Geometry Mode → Group With Children. Name the group “navmesh_source.”

Step 2: Add wall nodes to the group. Select your wall TileMap or StaticBody2D. Inspector → Node tab → Groups → Add “navmesh_source.”

Step 3: Set Parsed Geometry Type to Both. Some walls are colliders, some are mesh outlines. Both Types covers all bases.

Step 4: Bake. Click NavigationRegion2D in scene tree. Click the “Bake NavigationPolygon” button in the inspector preview. The polygon updates to enclose the walkable area, with walls excluded.

Runtime Bake

extends NavigationRegion2D

func rebake_for_destruction(broken_wall: Node2D) -> void:
    broken_wall.queue_free()
    await get_tree().process_frame
    bake_navigation_polygon(true)   # async

For dynamically changing levels, rebake after the change. Async bake doesn’t block the main thread.

NavigationObstacle2D for Dynamic Carve

For obstacles that move at runtime (a moving block, a temporarily-locked door), use NavigationObstacle2D instead of rebaking. The obstacle creates a runtime hole in the navmesh that agents avoid without re-baking.

Verifying

Project Settings → Debug → Settings → Visible Navigation. Reload the scene. The navmesh renders as a colored polygon. Walk the camera; navmesh should follow walkable area, miss walls. If walls appear inside, the source group doesn’t include them.

Understanding the issue

This bug class falls into a pattern that's worth understanding beyond the specific case. In Godot Engine, the underlying behavior is shaped by how the engine layers its abstractions - the public API you call, the runtime systems that respond, and the platform-specific implementations underneath. A bug at any layer can produce symptoms that look like they originate at a different layer. Triaging effectively means recognizing which layer the symptom belongs to, even when the gameplay code is what's visible.

The specific bug described above is the kind that surfaces during integration rather than unit testing. It depends on a combination of factors: the asset configuration, the runtime state, the platform's specific behavior. In isolation, each piece looks correct; in combination, the bug emerges. This is why thorough integration testing - playing the actual game in realistic conditions - catches things that automated tests miss.

Why this happens

This bug class disproportionately affects late-stage development. The work to surface it is interactive testing in realistic conditions, which only really happens after the gameplay is in place and assets are populated. Catching it early requires deliberate testing of conditions that look unimportant.

At the engine level, the behavior comes from a deliberate design decision in Godot. The engine team chose a particular trade-off - usually performance versus convenience, or generality versus specificity - and that trade-off has consequences when you push against it. Understanding the trade-off is what turns 'this bug is mysterious' into 'this bug is the expected consequence of this design'.

Verifying the fix

For shipping games, the safest verification is a staged rollout. Apply the fix to 1% of players for 24 hours; watch the affected metric; expand if green. Skipping the staged rollout means the verification is the entire player base, which is too high a stakes for most fixes.

Reproducibility is the prerequisite for verification. If you can't reliably reproduce the bug pre-fix, you can't reliably verify it post-fix. Spend time getting a clean reproduction before you write any fix code. The fix is fast once you understand the reproduction; the reproduction is the slow part.

Variations to watch for

Related bug classes often share the same root cause. If you find yourself fixing this issue, look for cousins: similar symptoms in adjacent systems, the same data flow but a different value, or the same fix pattern in another module. The catalog of 'we've seen this before' becomes valuable institutional knowledge.

Adjacent bugs often share a root cause. After fixing the case you've found, spend an hour searching the codebase for similar patterns. What's the same call with different arguments? The same data flow with a different entity type? The same lifecycle issue in a sibling system? Each match is a candidate for the same fix, or a related fix that prevents future bugs of the same class.

In production

In shipping builds, this issue may interact with other production-only behavior. Stripping, encryption, asset bundling, and platform-specific code paths can each modify the symptoms. When players report a related issue, capture build SHA, platform, and any feature flags - those three fields cover most of the production-only variations.

When triaging a similar issue in production, prioritize gathering data over hypothesizing causes. A player report describes a symptom; what you need is a build SHA, a session timestamp, and ideally a screen recording or session replay. With those, the bug becomes tractable. Without them, you're guessing at hypothetical reproductions that may not match what the player actually hit.

Performance considerations

If this issue manifests under high load (many actors, many particles, many network connections), profile the post-fix code path with realistic counts. The original cost was a bug; the new cost is real work, and real work has a budget.

Diagnostic approach

Diagnosing this class of bug benefits from a structured approach: confirm the symptom, isolate the variables, hypothesize the cause, and verify the hypothesis before writing fix code. Skipping the isolation step is the most common mistake; without it, fixes often address symptoms while the underlying cause continues to produce other variations.

For Godot-specific diagnostics, the editor's profiler is the canonical starting point. Capture a representative frame with the symptom present; compare against a frame without the symptom; the diff often points directly at the cause. If the symptom is non-deterministic, capture multiple frames and look for the pattern - the cause is usually a state transition or a specific input value rather than a continuous effect.

Tooling and ecosystem

Modern engine versions ship better tooling for this kind of issue than older versions. If you're on an older release, the diagnostic step may take significantly longer because the tools you'd want don't exist yet. Sometimes the right answer is upgrading rather than fighting through limited tooling.

Within Godot, the relevant diagnostic surfaces include the standard frame debugger, memory profiler, and engine-specific debug overlays. Each one shows a different facet of what's happening. The frame debugger reveals draw call ordering and state transitions; the memory profiler shows allocation patterns; the debug overlay reveals per-system state. Bugs that resist one tool usually surrender to another - the trick is knowing which tool to reach for first.

Edge cases and pitfalls

Edge cases for this class of issue often involve specific timing: the first frame after a state change, the last frame before a transition, frames where multiple subsystems update simultaneously. Reproducing these reliably is part of what makes the bug class hard to test.

When writing a regression test for this fix, focus on the boundary conditions that surfaced the original bug. Tests that exercise the happy path catch obvious regressions; tests that exercise the boundary catch the subtler regressions that look like new bugs but are really the original returning. The latter are the tests that earn their keep over the long life of the project.

Team communication

When this bug class affects multiple teams (often the case for cross-system issues), early communication prevents duplicate work. The team that owns the symptom may not own the cause. A 15-minute conversation at the start of triage often saves hours of independent investigation.

If this fix touches a system several engineers work in, a short writeup in the team's engineering channel helps. Not a full design doc - a paragraph explaining what was wrong, what's fixed, and what to watch for. Future engineers encountering similar symptoms will search for the fix; making it findable is a small investment that pays back later.

“Group source. Both types. Bake. Walls become walls.”

Related Issues

For NavigationAgent2D not pathing, see agent not pathing. For dynamic obstacle, see obstacle blocking.

Source group. Bake. The pathfinding sees the level.