What causes a Unity Rigidbody2D passing through colliders?

The Rigidbody2D uses discrete collision detection, so a fast body moves past a thin collider between physics steps before contact is checked, tunneling through.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix a Unity Rigidbody2D Passing Through Colliders

Quick answer: Set the Rigidbody2D's Collision Detection to Continuous, thicken thin colliders, and lower the fixed timestep for fast bodies.

A Rigidbody2D passing through colliders is 2D tunnelling. Continuous detection fixes it. Here is how.

How to fix it

1. Set Continuous collision detection

Change the Rigidbody2D's Collision Detection from Discrete to Continuous so the engine sweeps the collider along its path between steps, catching thin colliders a fast body would otherwise skip.

2. Thicken thin colliders

Very thin 2D colliders (a one-unit wall) are easy to tunnel through. Give walls and floors more thickness so there is more for a fast body to collide with.

3. Lower the fixed timestep

Reduce the fixed timestep so 2D physics steps more often, covering less distance per step. This shrinks the gap a fast Rigidbody2D can jump across between collision checks.

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.

Most of the time the fix is small. Seeing the failure clearly is the part that actually costs you.