How to Fix a Unity Avatar Mask Upper-Body Layer Also Animating the Legs

You added an upper-body action layer so the character can wave while walking, but the legs freeze or pop. That means the mask is not actually restricting the layer to the upper body. Here is how to scope it correctly.

How to fix it

1. Build the avatar mask correctly

Create an AvatarMask asset, open the Humanoid section, and enable only the chest, arms, and head. Disable the legs, feet, and root so the layer cannot drive them.

2. Assign the mask to the layer

In the Animator's Layers panel, click the layer's gear icon and set the Mask field to your avatar mask. Without this, the layer animates every bone regardless of the asset.

3. Check Override vs Additive

An Override layer at weight 1 replaces the masked bones entirely. If you want the wave to blend on top of the walk, set the layer Blending to Additive or lower its weight.

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.