What causes lights popping from the per-object light limit in forward rendering?

Forward rendering caps how many lights shade each object per pass, so when more lights are in range than the limit allows, the engine drops the lowest-priority ones and they visibly pop.

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 Lights Popping On and Off from the Per-Object Light Limit in Forward Rendering

Quick answer: Raise the additional-lights-per-object limit in the URP asset, set important lights to Important render mode, or switch to a Forward+/deferred path that has no small per-object cap.

In forward rendering each object can only be lit by a fixed number of lights at once. When too many are nearby, lights flicker in and out as ranking changes. Raising the cap or moving to Forward+ stops the popping.

How to fix it

1. Raise the per-object light count

In the URP Asset, increase Additional Lights > Per Object Limit (up to its max). Built-in forward uses the Pixel Light Count in Quality settings; raise it there.

2. Mark key lights Important

Set must-have lights' Render Mode to Important so they are always evaluated per-pixel and never demoted to the dropped vertex/SH set.

3. Reduce lights in range

Cut the number of overlapping lights or shrink their ranges so the count near any object stays under the cap, eliminating the ranking churn that causes popping.

4. Switch to Forward+ or deferred

Forward+ and deferred rendering remove the tiny per-object light cap, so many lights can affect an object without the per-object limit dropping them.

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.

The bug you can't reproduce isn't gone — it's just invisible until you capture it from the player's device.