I am playing Enigmatica 2, and I added FoamFix, along with some other client-side mods, to the modpack.

I crash on startup with FoamFix installed, but I can run the game just fine if I remove FoamFix.

Log: https://pastebin.com/raw/7qDk11U1

Minecraft version: 1.12.2
Forge version: 14.23.1.2562
FoamFix version: 0.8.2-Anarchy (official)

Yeah, I just realized this, so I came here to close the issue.

I was adding some client-side mods to the modpack I’m playing, and I thought it didn’t have FoamFix because it wasn’t listed on the file page, but I forgot that it isn’t on CurseForge. Whoops.

Right. No problem, I've seen this happen even with the Curse launcher's update process gone wrong.

[00:39:39] [main/WARN]: Found FMLCorePluginContainsFMLMod marker in foamfix-0.8.1-1.12-anarchy.jar. This is not recommended, @mods should be in a separate jar from the coremod.
[00:39:39] [main/WARN]: The coremod pl.asie.foamfix.coremod.FoamFixCore does not have a MCVersion annotation, it may cause issues with this version of Minecraft
[00:39:39] [main/WARN]: Found FMLCorePluginContainsFMLMod marker in FoamFix-1.12.2-0.8.2-Anarchy.jar. This is not recommended, @mods should be in a separate jar from the coremod.
[00:39:39] [main/WARN]: The coremod pl.asie.foamfix.coremod.FoamFixCore does not have a MCVersion annotation, it may cause issues with this version of Minecraft

You have FoamFix twice. Don't have FoamFix twice, please.