I tried installing the chickens mod into a modpack, and when I booted up my whole screen was that pink and black no texture block. Game crashed right after that with this error message:

The game crashed whilst rendering overlay
Error: java.lang.IllegalAccessError: failed to access class net.minecraft.client.renderer.block.model.ItemModelGenerator$SpanFacing from class net.mehvahdjukaar.modelfix.ModelFix (net.minecraft.client.renderer.block.model.ItemModelGenerator$SpanFacing is in module [email protected] of loader 'TRANSFORMER' @5f0f70c7; net.mehvahdjukaar.modelfix.ModelFix is in module [email protected] of loader 'TRANSFORMER' @5f0f70c7)

This is using the 1.19.2 version of the mod.

What was the solution to this problem? I'm having the exact same issue.

Based on the error line from class net.mehvahdjukaar.modelfix.ModelFix, it looks to me that another mod and the Chickens mod are clashing. Googling "model fix mod" brings up a mod called "Model Gap Fix", which I'm assuming is the offender.

I don't know what is causing the two mods to not like each other specifically, but I would bring up the issue with them as well.

Thank you so much. I'll dig into that.