DaemonUmbra

https://docs.oracle.com/javase/tutorial/java/package/namingpkgs.html

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

1.12 is no longer supported here, so if you're using that version please update. Please don't post in old threads, if you have an issue please make your own thread.

That's not debug.log either, please provide the actual debug.log (more info in my signature)

When you ran Forge did you have Optifine?

The name(s) of one or more of your mods indicate you did not get them from a reputable source. Please visit StopModReposts to learn why this is a bad thing.

Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)

Does this happen with just Forge?

Run JarFix and try again

No, there isn't an alternative

Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)

try deleting forge-client.toml from your config folder

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Performant is broken

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

I mean you close the game at some point when it freezes, right? I'm asking how long you let it sit before closing it.

Go into your world save, serverconfigs, and delete usefulbackpacks-server.toml

What is the purpose of doing this?

Because it's old as balls. Because nobody here remembers how it works. Because everybody on the dev team wants to focus on what's current. Because we want people to update rather than begging modders to backport. Because it's a rule on these forums.

If you start a world with just Forge do the commands work fine?

Forge shouldn't be messing with those, do you have other mods installed?

Look up fillStateContainer

Can you provide screenshots of what you're talking about?

Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)

As far as I know fixing this requires uninstalling every version of Java that you have before reinstalling. Not reinstalling a single version, not the repair option in an installer, but completely and utterly removing Java from your PC so anything shared also gets reset.