How to Fix Unity Terrain Collider Not Matching the Rendered Surface

Floating or sinking on terrain means the physics heightfield no longer matches the visual heightmap. Forcing the collider to resync to the current heightmap fixes it. Here is how.

How to fix it

1. Sync the heightmap after edits

If you modify heights at runtime with SetHeights, call TerrainData.SyncHeightmap() so the collider rebuilds from the new data instead of the cached version.

2. Reassign the collider terrainData

Setting terrainCollider.terrainData = terrain.terrainData (or disabling and re-enabling the collider) forces PhysX to rebuild the heightfield from the current asset.

3. Check for shared TerrainData

If two terrains accidentally reference the same TerrainData, edits to one shift the other's collider. Give each terrain its own TerrainData asset.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every Unity error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.