Failed to load required shader programs

Caught error loading resourcepacks, removing all selected resourcepacks java.util.concurrent.CompletionException: java.lang.RuntimeException: Failed to load required shader programs:

• minecraft:core/rendertype_armor_cutout_no_cull (VertexFormat[Position, Color, UV0, UV1, UV2, Normal]): Could not find shader: minecraft:rendertype_armor_cutout_no_cull (VERTEX)

• minecraft:core/rendertype_text (VertexFormat[Position, Color, UV0, UV2]): Could not find shader: minecraft:rendertype_text (VERTEX)

Why does it happen?

This happens because Minecraft 1.21.2 changed where shaders .vsh and .fsh files have to be put.

The default shaders path is changed to assets/minecraft/shaders/<name>.vsh instead of assets/minecraft/shaders/core/<name>.vsh.

This made the core folder not mandatory and not automatically taken into account by the game.

To fix this you have to open each of your custom shaders .json files in the core folder and update the vertex and fragment path including core/ as prefix folder.

The overlay folder is called ia_overlay_1_21_2 on the final .zip file.

How to fix automatically

ItemsAdder offers a setting that automatically fixes these shaders for you.

It will update the .json files automatically and create an overlay to allow older clients to still recognize the old format and the new clients (1.21.2+) to recognize the old format.

This requires you to run /iazip to regenerate your pack.

config.yml

pre_1_21_2_shaders_fix:
  enabled: true