How to Fix Unity Physics Behaving Differently on Different Platforms

Unity physics differing across platforms is frame-rate dependence and float divergence. Here is how to handle it.

How to fix it

1. Use a fixed timestep

Run physics in FixedUpdate at a fixed timestep so it behaves the same regardless of frame rate. Frame-rate-dependent physics gives different results on platforms running at different frame rates.

2. Avoid frame-rate-dependent code

Do not apply forces or movement per frame in Update for physics objects. Keep physics in FixedUpdate with fixedDeltaTime so the simulation does not vary with how fast each platform renders.

3. Do not rely on exact determinism

Unity's physics is not deterministic across platforms due to floating-point differences. Do not build gameplay on exact cross-platform physics determinism; use a fixed timestep for consistency and authoritative state for multiplayer.

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.