How to Fix a Compound Collider's Wrong Center of Mass

A compound rigidbody (several child colliders) that pivots around a strange axis or refuses to settle upright has a center of mass computed from collider volume, which rarely matches the visual weight. Here is how to fix it.

How to fix it

1. Override the center of mass

Set rb.centerOfMass in local space to the intended balance point. Once you assign it manually, Unity stops recomputing it from the colliders when they change.

2. Set the inertia tensor if needed

For deliberate spin behavior, also assign rb.inertiaTensor and inertiaTensorRotation; otherwise call ResetInertiaTensor() after fixing colliders to recompute cleanly.

3. Match colliders to real mass

If you prefer auto-computation, resize or reposition child colliders so their combined volume reflects where the object's weight actually is, e.g. a denser base.

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.