What causes the Unity particle Lights module not casting light?

The Lights module has no light prefab assigned, the Ratio is zero, or Maximum Lights is too low, so no real-time lights are created for the particles.

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 the Unity Particle Lights Module Not Casting Light

Quick answer: Assign a Light prefab to the Lights module, raise the Ratio above zero, and increase Maximum Lights, keeping intensity and range sensible for performance.

The Lights module spawns actual Light components for a fraction of particles. Without a prefab, a non-zero ratio, and a light budget, it produces no light. Here is how.

How to fix it

1. Assign a Light prefab

Create a prefab with a Light component (point or spot) and assign it in the Lights module. With no prefab the module has nothing to instantiate and emits no light.

2. Set Ratio and Maximum Lights

Raise Ratio above zero so a portion of particles get lights, and set Maximum Lights high enough that at least some are active; a cap of zero or one starves the effect.

3. Budget intensity and range

Real-time lights are expensive, so keep counts low. Use Use Particle Color and Size Affects Range so the lights track the effect while staying within a performance budget.

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.

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