Fixing Old Lighting Shaders When They Don't Appear or Look Wrong

If you installed the pack but your world looks exactly like plain vanilla, or something seems off, work through these checks in order.

The shader isn't showing at all

1. Confirm you have a loader. Shader packs do nothing without Iris or OptiFine. If Options > Video Settings has no Shaders or Shader Packs button, the loader isn't running.

2. Check the folder. The pack must be in shaderpacks, not resourcepacks. Putting it in the resource pack menu won't activate it.

3. Make sure it's selected. Open the shader menu, click the pack so it's highlighted and apply it. Having it in the list is not enough.

4. Remember the effect is subtle. This pack recreates classic lighting and deliberately keeps the vanilla style. Compare it with shaders off in a cave or at dusk, where the change is easiest to see.

It looks wrong or performs badly

1. Switch shaders off, then reapply the pack. This clears up many one-off glitches.

2. Disable other visual mods or resource packs one at a time. A conflict between them can look like a shader problem.

3. Update your graphics drivers. This is a common fix for shader issues on older laptops.

4. To go back to normal visuals at any time, open the shader menu and pick the option that turns shaders off.