What causes a shader keyword stripped from the build?

Unity's build-time variant stripping removed the keyword's variant because nothing in a scene or always-included shader list referenced it at build time, so the runtime keyword toggle has no compiled variant to switch to.

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 Shader Keyword Working in the Editor but Stripped From the Build

Quick answer: Add the shader to Always Included Shaders, reference the keyword from a material in a scene, or whitelist it with a ShaderVariantCollection so the variant ships.

A shader feature toggled at runtime with EnableKeyword can silently disappear in a build because the editor compiles variants on demand but builds only ship variants Unity thinks are used. You must tell the build to keep it. Here is how to fix it.

How to fix it

1. Add it to Always Included Shaders

In Project Settings > Graphics, add the shader under Always Included Shaders so all of its declared variants are compiled and shipped regardless of scene usage.

2. Ship a ShaderVariantCollection

Record the keyword combinations you toggle into a ShaderVariantCollection asset and reference it from Graphics settings; Unity preserves exactly those variants and warms them at load.

3. Use the right multi_compile pragma

Declare runtime-toggled keywords with #pragma multi_compile (not shader_feature); shader_feature variants are stripped unless a material in the build actually enables 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.

A crash you can name from its stack trace is a crash you can usually fix in minutes.