How to Fix the Overlapping Lightmap UV Warning in Unity

Overlapping lightmap UVs cause baked-lighting bleeding. Generating proper UV2 fixes it. Here is how.

How to fix it

1. Enable Generate Lightmap UVs

On the model's import settings, turn on Generate Lightmap UVs so Unity creates a non-overlapping UV2 channel for baking. This fixes most cases without touching the source mesh.

2. Author a clean UV2

For better control, author a dedicated lightmap UV channel in your 3D tool with no overlaps and adequate padding, so baked lighting does not bleed between faces.

3. Rebake lighting

After fixing the UVs, rebake the lighting. The warning and the bleeding artifacts clear once each surface has its own distinct region in the lightmap.

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.