Ugdhar

So I just noticed near the top of the log it says "Launched instance in offline mode", does that mean it is bypassing Minecraft account authentication? If so, that is probably the issue.

Then I would say the issue is most likely prism launcher, if using the vanilla launcher works. Perhaps there is an update for it or something?

Try using the vanilla launcher, if it fails post that log

Please read the FAQ for information on how to properly share logs.

Please read the FAQ for how to share logs properly. Browsing on curseforge, looks like those versions of JEI are all Beta, but they do exist on there. If the overwolf client won't download them, then you'll have to do it manually.

What mods did you add? I also notice you're using that fabric frankenstein mod, could you have both the fabric version and forge version of a mod installed?

That is a fabric log, this is the forge support forums. You would probably have better luck asking for support where fabric support is given.

Neoforge is not the same as Forge, you would probably get better results asking for help wherever Neoforge support is given. Also, single player games are essentially local multiplayer games, there's a client and a server running, just both on the same computer. That's why the "open to LAN" button works. Always post full logs when asking for support (that doesn't change between Forge/Neoforge, or anything for that matter), they likely contain information that would help determine the issue, even if you don't recognize the usefulness of it.

Firstly, I would not advise running as root for this, even for testing/trying to get it to work. Did that generate any logs? Post your run.sh and user_jvm_args.txt, maybe there's something in there that could be changed.

Did you try this?

It appears to be using Fabric, as this is the Forge forums, you would probably get better results asking wherever fabric support is given. Based on your story, I would guess world corruption, I'd try loading a backup.

I split your reply to a year old post into a separate support post. It's best to do it this way and not just reply to someone that looks like they have the same problem Please read the FAQ and post logs as described there, it will help you get assistance.

These are the Minecraft Forge forums, and you are using Fabric. You would probably get better results asking for help wherever Fabric support is given. I also moved your post to the support forum, as Modder Support is for programmers creating Forge mods.

Please read the FAQ (https://forums.minecraftforge.net/topic/125488-rules-and-frequently-asked-questions-faq/) and post logs as described there, they may contain clues as to what is going wrong.

I moved your post to the support forum, as this is a request for support. Please read the FAQ, and post logs as described there. It will provide more information that will help people help you.