Eplex

After much trial and error I also checked in with the COFH Discord and was able to find out that "DupeFix Project" was responsible for the crash (java.lang.NoClassDefFoundError: cofh/thermalexpansion/gui/container/storage/ContainerSatchel). After removing that mod everything worked.

I can confirm after more testing that it is an issue with Thermal Expansion, If I remove all Thermal mods and slowly add them back (COFH Core -> COFH World -> Thermal Foundtion) when I add Thermal Expansion 5.5.7.1 the crash starts which is weird considering the mod is used on many other 1.12.2 packs.

I'm trying to update an old modpack - Specifically - https://www.curseforge.com/minecraft/modpacks/awakening-sky-of-diamonds, I've already updated it and added AE2 and it's newer versions (this all worked fine) but I wanted to add AE2 fluid crafting and Lazy Ae2 patch/tweaks which require mixinbooter. I've removed all the old incompatible files i.e. Vanilla Fix and installed new equivalent mods (censoredASM/Vintage Fix). I'm able to get into the game and into a fresh game world but when I try and mine/pick up items the game crashes with this error which appears to be around Thermal Expansion/Cofh Core: https://mclo.gs/8DwXeoA