How to Fix a Rigidbody Falling Asleep on a Conveyor and Stopping in Unity

Boxes ride your conveyor for a moment then stop dead. Their velocity fell below the sleep threshold so PhysX put them to sleep and friction no longer moves them. Keeping them awake or driving velocity directly fixes it.

How to fix it

1. Wake the body on the belt

While an object overlaps the conveyor trigger, call rb.WakeUp() each FixedUpdate so it cannot enter sleep and lose contact with the moving surface.

2. Lower the sleep threshold

Reduce Rigidbody.sleepThreshold (or the project sleep threshold) so bodies on the belt stay awake at the low velocities the conveyor imparts.

3. Drive velocity directly

Instead of relying on surface friction, set the body's velocity toward the belt direction each step while it is on the conveyor so motion does not depend on it staying awake.

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.