The game crashed whilst initializing game Error: net.minecraftforge.fml.ModLoadingException: Forge (forge) encountered an error during the sided_setup event phase

By itself the game launches perfectly fine with forge, but the moment I put Optifine into the mods folder it gives me this error and crashes the game on startup. Anybody know why? I've tried a different version of Optifine and that didn't work. I'm using both 1.19.3 versions. I switched my forge version to the recommended 1.19.3 version but it still gives me the same error on startup.

Here's the log: https://pastebin.com/Xy7W16TN

Then don't use Optifine. It tends to play poorly with any mod that includes rendering or mixins. There are other mods like rubidium, oculus/iris out there that are much better.

1. I'm having the same problem griffithpilled, still unsure how to fix it but if I find a way I'll let you know! I think a problem could be that we're trying to run it on 1.19.3 and optifine doesn't yet have a full-proof download, the only 1.19.3 optifine downloads that exist currently are still previews and not entirely done. - In other words, not a lot can be done at the moment. This is what I'm assuming anyway, but as I said if I find a fix I'll come back with an update.

2. ChampionAsh5357, no offense but that is not the most helpful comment in the world. Especially if someone posts lookin for a fix, not a replacement.

15 hours ago, Køtø said:

2. ChampionAsh5357, no offense but that is not the most helpful comment in the world. Especially if someone posts lookin for a fix, not a replacement.

Makes sense since there is no fix for OptiFine. OptiFine currently does not support Forge 1.19.3. However, that doesn't change the underlying issue that OptiFine is a mod which breaks almost any mod which tries to do any sort of custom rendering. A fix, as I mentioned, would be to use alternative mods rather than OptiFine. If you want to fix OptiFine, tell them to care more about mod compatibility.

Apologies if my original explanation was not clear.