Crash Log: https://pastebin.com/uLzisEVv

After a quick check, it seems the problem is with net.frostbyte.slabsandstairs.screen.SawmillScreenHandler, it uses the class net.minecraft.recipe.Recipe.RecipeEntry which doesn't exist yet in 1.20.1. I don't know if you wanna take the effort to fix this for such a minor version, I'm not sure if the changes done to the SawmillScreenHandler class in 9829df1 would be easily revertible for a seperate 1.20.1 version. I should probably just update my pack to 1.20.2 tbh 😄

As a sidenote, I really appreciate your mod, it's the only additional slabs/stairs/walls mod that doesn't add a ton of unnecessary stuff and keeps the vanilla feel.

Okay I should have checked that beforehand, but since there actually is already a seperate 1.20.1 version on Modrinth I will just close this issue, although the required MC version should probably be changed to not allow 1.20.1 so launchers will download the proper version.