Feather Client Crash with Iris Shaders: [Vertex] Unsupported format

What it looks like in the log

java.lang.RuntimeException: [Vertex] Unsupported format format: 10 elements: Position=3,Position,Float Color=4,Vertex Color,Unsigned Byte UV0=2,UV,Flo

How to fix it

1. Switch from Feather Client to a standard launcher supported by Iris and Sodium, such as Prism Launcher, the Modrinth App, ATLauncher, or the official Minecraft Launcher.
2. If you want to keep using Feather Client, disable shaders in Video Settings or remove the Iris Shaders JAR from your Feather profile's mods folder.
3. If the crash happens specifically when pressing F5 or looking at players, turn off Feather Client's custom nametag, levelhead, or Cosmetics HUD overlays in Feather's in-game settings.

Check your own log