What causes a particle system allocating garbage every frame?

Calling GetParticles into a freshly allocated array each frame (or using the params collision callback) allocates a new managed array every call, churning the GC.

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 Particle System Allocating Garbage Every Frame in Unity

Quick answer: Allocate the Particle[] buffer once, reuse it across frames with GetParticles/SetParticles, and avoid the allocating collision event overloads in hot paths.

Reading or writing particle arrays per frame allocates if you create a new array each time. Caching one buffer and reusing it removes the per-frame garbage. Here is how.

How to fix it

1. Cache the particle buffer

Allocate a single ParticleSystem.Particle[] sized to Max Particles once, then call GetParticles(buffer) each frame into it instead of allocating a new array.

2. Write back into the same array

Modify particles in place in the cached buffer and call SetParticles(buffer, count), avoiding any intermediate allocations during the update.

3. Avoid allocating callbacks

The List<ParticleCollisionEvent> collision API can allocate if the list grows; preallocate it and reuse it, and prefer the non-allocating GetCollisionEvents overload.

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 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.

Ship the fix, watch the signature disappear from the next build. That's how you know it's really gone.